Lipoprotein (a) [Lp(a)] is a risk factor for CVD and a target of therapy, but Lp(a) measurements are not globally standardized. Commercially available assays generally use polyclonal antibodies that detect multiple sites within the kringle (K)IV₂ repeat region of Lp(a) and may lead to inaccurate assessments of plasma levels. With increasing awareness of Lp(a) as a cardiovascular risk factor and the active clinical development of new potential therapeutic approaches, the broad availability of reagents capable of providing isoform independence of Lp(a) measurements is paramount. To address this issue, we generated a murine monoclonal antibody that binds to only one site on apo(a). A BALB/C mouse was immunized with a truncated version of apo(a) that contained eight total KIV repeats, including only one copy of KIV₂. We generated hybridomas, screened them, and successfully produced a KIV₂-independent monoclonal antibody, named LPA-KIV9. Using a variety of truncated apo(a) constructs to map its binding site, we found that LPA-KIV9 binds to KIV₉ without binding to plasminogen. Fine peptide mapping revealed that LPA-KIV9 bound to the sequence ⁴⁰⁷⁶LETPTVV⁴⁰⁸² on KIV₉. In conclusion, the generation of monoclonal antibody LPA-KIV9 may be a useful reagent in basic research studies and in the clinical application of Lp(a) measurements.

Sphingolipids have become established participants in the pathogenesis of obesity and its associated maladies. Sphingosine kinase 1 (SPHK1), which generates S1P, has been shown to increase in liver and adipose of obese humans and mice and to regulate inflammation in hepatocytes and adipose tissue, insulin resistance, and systemic inflammation in mouse models of obesity. Previous studies by us and others have demonstrated that global sphingosine kinase 1 KO mice are protected from diet-induced obesity, insulin resistance, systemic inflammation, and NAFLD, suggesting that SPHK1 may mediate pathological outcomes of obesity. As adipose tissue dysfunction has gained recognition as a central instigator of obesity-induced metabolic disease, we hypothesized that SPHK1 intrinsic to adipocytes may contribute to HFD-induced metabolic pathology. To test this, we depleted Sphk1 from adipocytes in mice (SK1^fatKO) and placed them on a HFD. In contrast to our initial hypothesis, SK1^fatKO mice displayed greater weight gain on HFD and exacerbated impairment in glucose clearance. Pro-inflammatory cytokines and neutrophil content of adipose tissue were similar, as were levels of circulating leptin and adiponectin. However, SPHK1-null adipocytes were hypertrophied and had lower basal lipolytic activity. Interestingly, hepatocyte triacylglycerol accumulation and expression of pro-inflammatory cytokines and collagen 1a1 were exacerbated in SK1^fatKO mice on a HFD, implicating a specific role for adipocyte SPHK1 in adipocyte function and inter-organ cross-talk that maintains overall metabolic homeostasis in obesity. Thus, SPHK1 serves a previously unidentified essential homeostatic role in adipocytes that protects from obesity-associated pathology. These findings may have implications for pharmacological targeting of the SPHK1/S1P signaling axis.

Cognitive decline with age is a harmful process that can reduce quality of life. Multiple factors have been established to contribute to cognitive decline, but the overall etiology remains unknown. Here, we hypothesized that cognitive dysfunction is mediated, in part, by increased levels of inflammatory cytokines that alter allopregnanolone (AlloP) levels, an important neurosteroid in the brain. We assessed the levels and regulation of AlloP and the effects of AlloP supplementation on cognitive function in 4-month-old and 24-month-old male C57BL/6 mice. With age, the expression of enzymes involved in the AlloP synthetic pathway was decreased and corticosterone (CORT) synthesis increased. Supplementation of AlloP improved cognitive function. Interestingly, interleukin 6 (IL-6) infusion in young animals significantly reduced the production of AlloP compared with controls. It is notable that inhibition of IL-6 with its natural inhibitor, soluble membrane glycoprotein 130, significantly improved spatial memory in aged mice. These findings were supported by in vitro experiments in primary murine astrocyte cultures, indicating that IL-6 decreases production of AlloP and increases CORT levels. Our results indicate that age-related increases in IL-6 levels reduce progesterone substrate availability, resulting in a decline in AlloP levels and an increase in CORT. Furthermore, our results indicate that AlloP is a critical link between inflammatory cytokines and the age-related decline in cognitive function.

Accompanied with nutrition transition, non-HDL-C levels of individuals in Asian countries has increased rapidly, which has caused the global epicenter of nonoptimal cholesterol to shift from Western countries to Asian countries. Thus, it is critical to underline major genetic and dietary determinants. In the current study of 2,330 Chinese individuals, genetic risk scores (GRSs) were calculated for total cholesterol (TC; GRS_TC, 57 SNPs), LDL-C (GRS_LDL-C, 45 SNPs), and HDL-C (GRS_HDL-C, 65 SNPs) based on SNPs from the Global Lipid Genetics Consortium study. Cholesterol intake was estimated by a 74-item food-frequency questionnaire. Associations of dietary cholesterol intake with plasma TC and LDL-C strengthened across quartiles of the GRS_TC (effect sizes: –0.29, 0.34, 2.45, and 6.47; P_interaction = 0.002) and GRS_LDL-C (effect sizes: –1.35, 0.17, 5.45, and 6.07; P_interaction = 0.001), respectively. Similar interactions with non-HDL-C were observed between dietary cholesterol and GRS_TC (P_interaction = 0.001) and GRS_LDL-C (P_interaction = 0.004). The adverse effects of GRS_TC on TC (effect sizes across dietary cholesterol quartiles: 0.51, 0.82, 1.21, and 1.31; P_interaction = 0.023) and GRS_LDL-C on LDL-C (effect sizes across dietary cholesterol quartiles: 0.66, 0.52, 1.12, and 1.56; P_interaction = 0.020) were more profound in those having higher cholesterol intake compared with those with lower intake. Our findings suggest significant interactions between genetic susceptibility and dietary cholesterol intake on plasma cholesterol profiles in a Chinese population.

Bile acids, which are synthesized from cholesterol by the liver, are chemically transformed along the intestinal tract by the gut microbiota, and the products of these transformations signal through host receptors, affecting overall host health. These transformations include bile acid deconjugation, oxidation, and 7α-dehydroxylation. An understanding of the biogeography of bile acid transformations in the gut is critical because deconjugation is a prerequisite for 7α-dehydroxylation and because most gut microorganisms harbor bile acid transformation capacity. Here, we used a coupled metabolomic and metaproteomic approach to probe in vivo activity of the gut microbial community in a gnotobiotic mouse model. Results revealed the involvement of Clostridium scindens in 7α-dehydroxylation, of the genera Muribaculum and Bacteroides in deconjugation, and of six additional organisms in oxidation (the genera Clostridium, Muribaculum, Bacteroides, Bifidobacterium, Acutalibacter, and Akkermansia). Furthermore, the bile acid profile in mice with a more complex microbiota, a dysbiosed microbiota, or no microbiota was considered. For instance, conventional mice harbor a large diversity of bile acids, but treatment with an antibiotic such as clindamycin results in the complete inhibition of 7α-dehydroxylation, underscoring the strong inhibition of organisms that are capable of carrying out this process by this compound. Finally, a comparison of the hepatic bile acid pool size as a function of microbiota revealed that a reduced microbiota affects host signaling but not necessarily bile acid synthesis. In this study, bile acid transformations were mapped to the associated active microorganisms, offering a systematic characterization of the relationship between microbiota and bile acid composition.

Among the virulence factors in Neisseria infections, a major inducer of inflammatory cytokines is the lipooligosaccharide (LOS). The activation of NF-B via extracellular binding of LOS or lipopolysaccharide (LPS) to the toll-like receptor 4 and its coreceptor, MD-2, results in production of pro-inflammatory cytokines that initiate adaptive immune responses. LOS can also be absorbed by cells and activate intracellular inflammasomes, causing the release of inflammatory cytokines and pyroptosis. Studies of LOS and LPS have shown that their inflammatory potential is highly dependent on lipid A phosphorylation and acylation, but little is known on the location and pattern of these posttranslational modifications. Herein, we report on the localization of phosphoryl groups on phosphorylated meningococcal lipid A, which has two to three phosphate and zero to two phosphoethanolamine substituents. Intact LOS with symmetrical hexa-acylated and asymmetrical penta-acylated lipid A moieties was subjected to high-resolution ion mobility spectrometry MALDI-TOF MS. LOS molecular ions readily underwent in-source decay to give fragments of the oligosaccharide and lipid A formed by cleavage of the ketosidic linkage, which enabled performing MS/MS (pseudo-MS³). The resulting spectra revealed several patterns of phosphoryl substitution on lipid A, with certain species predominating. The extent of phosphoryl substitution, particularly phosphoethanolaminylation, on the 4'-hydroxyl was greater than that on the 1-hydroxyl. The heretofore unrecognized phosphorylation patterns of lipid A of meningococcal LOS that we detected are likely determinants of both pathogenicity and the ability of the bacteria to evade the innate immune system.

Adaptive thermogenesis is highly dependent on uncoupling protein 1 (UCP1), a protein expressed by thermogenic adipocytes present in brown adipose tissue (BAT) and white adipose tissue (WAT). Thermogenic capacity of human and mouse BAT can be measured by positron emission tomography-computed tomography quantifying the uptake of ¹⁸F-fluodeoxyglucose or lipid tracers. BAT activation is typically studied in response to cold exposure or treatment with β-3-adrenergic receptor agonists such as CL316,243 (CL). Currently, it is unknown whether cold-stimulated uptake of glucose or lipid tracers is a good surrogate marker of UCP1-mediated thermogenesis. In metabolic studies using radiolabeled tracers, we found that glucose uptake is increased in mildly cold-activated BAT of Ucp1^–/– versus WT mice kept at subthermoneutral temperature. Conversely, lower glucose disposal was detected after full thermogenic activation achieved by sustained cold exposure or CL treatment. In contrast, uptake of lipoprotein-derived fatty acids into chronically activated thermogenic adipose tissues was substantially increased in UCP1-deficient mice. This effect is linked to higher sympathetic tone in adipose tissues of Ucp1^–/– mice, as indicated by elevated levels of thermogenic genes in BAT and WAT. Thus, glucose and lipoprotein handling does not necessarily reflect UCP1-dependent thermogenic activity, but especially lipid uptake rather mirrors sympathetic activation of adipose tissues.

Phospholipids, including ether phospholipids, are composed of numerous isomeric and isobaric species that have the same backbone and acyl chains. This structural resemblance results in similar fragmentation patterns by collision-induced dissociation of phospholipids regardless of class, yielding complicated MS/MS spectra when isobaric species are analyzed together. Furthermore, the presence of isobaric species can lead to misassignment of species when made solely based on their molecular weights. In this study, we used normal-phase HPLC for ESI-MS/MS analysis of phospholipids from bovine heart mitochondria. Class separation by HPLC eliminates chances for misidentification of isobaric species from different classes of phospholipids. Chromatography yields simple MS/MS spectra without interference from isobaric species, allowing clear identification of peaks corresponding to fragmented ions containing monoacylglycerol backbone derived from losing one acyl chain. Using these fragmented ions, we characterized individual and isomeric species in each class of mitochondrial phospholipids, including unusual species, such as PS, containing an ether linkage and species containing odd-numbered acyl chains in cardiolipin, PS, PI, and PG. We also characterized monolysocardiolipin and dilysocardiolipin, the least abundant but nevertheless important mitochondrial phospholipids. The results clearly show the power of HPLC-MS/MS for identification and characterization of phospholipids, including minor species.

Lipoprotein (a) [Lp(a)] is characterized by an LDL-like composition in terms of lipids and apoB100, and by one copy of a unique glycoprotein, apo(a). The apo(a) structure is mainly based on the repetition of tandem kringle domains with high homology to plasminogen kringles 4 and 5. Among them, kringle IV type 2 (KIV-2) is present in a highly variable number of genetically encoded repeats, whose length is inversely related to Lp(a) plasma concentration and cardiovascular risk. Despite it being the major component of apo(a), the actual function of KIV-2 is still unclear. Here, we describe the first high-resolution crystallographic structure of this domain. It shows a general fold very similar to other KIV domains with high and intermediate affinity for the lysine analog, -aminocaproic acid. Interestingly, KIV-2 presents a lysine binding site (LBS) with a unique shape and charge distribution. KIV-2 affinity for predicted small molecule binders was found to be negligible in surface plasmon resonance experiments; and with the LBS being nonfunctional, we propose to rename it "pseudo-LBS". Further investigation of the protein by computational small-molecule docking allowed us to identify a possible heparin-binding site away from the LBS, which was confirmed by specific reverse charge mutations abolishing heparin binding. This study opens new possibilities to define the pathogenesis of Lp(a)-related diseases and to facilitate the design of specific therapeutic drugs.

Porphyromonas gingivalis is a Gram-negative anaerobic periodontal microorganism strongly associated with tissue-destructive processes in human periodontitis. Following oral infection with P. gingivalis, the periodontal bone loss in mice is reported to require the engagement of Toll-like receptor 2 (TLR2). Serine-glycine lipodipeptide or glycine aminolipid classes of P. gingivalis engage human and mouse TLR2, but a novel lipid class reported here is considerably more potent in engaging TLR2 and the heterodimer receptor TLR2/TLR6. The novel lipid class, termed Lipid 1256, consists of a diacylated phosphoglycerol moiety linked to a serine-glycine lipodipeptide previously termed Lipid 654. Lipid 1256 is approximately 50-fold more potent in engaging TLR2 than the previously reported serine-glycine lipid classes. Lipid 1256 also stimulates cytokine secretory responses from peripheral blood monocytes and is recovered in selected oral and intestinal Bacteroidetes organisms. Therefore, these findings suggest that Lipid 1256 may be a microbial TLR2 ligand relevant to chronic periodontitis in humans.

ABCB4/MDR3 is located in the canalicular membrane of hepatocytes and translocates PC-lipids from the cytoplasmic to the extracellular leaflet. ABCB4 is an ATP-dependent transporter that reduces the harsh detergent effect of the bile salts by counteracting self-digestion. To do so, ABCB4 provides PC lipids for extraction into bile. PC lipids account for 40% of the entire pool of lipids in the canalicular membrane with an unknown distribution over both leaflets. Extracted PC lipids end up in so-called mixed micelles. Mixed micelles are composed of phospholipids, bile salts, and cholesterol. Ninety to ninety-five percent of the phospholipids are members of the PC family, but only a subset of mainly 16.0-18:1 PC and 16:0-18:2 PC variants are present. To elucidate whether ABCB4 is the key discriminator in this enrichment of specific PC lipids, we used in vitro studies to identify crucial determinants in substrate selection. We demonstrate that PC-lipid moieties alone are insufficient for stimulating ABCB4 ATPase activity, and that at least two acyl chains and the backbone itself are required for a productive interaction. The nature of the fatty acids, like length or saturation has a quantitative impact on the ATPase activity. Our data demonstrate a two-step enrichment and protective function of ABCB4 to mitigate the harsh detergent effect of the bile salts, because ABCB4 can translocate more than just the PC-lipid variants found in bile.

SLC19A2 and SLC19A3, also known as thiamine transporters (THTR) 1 and 2, respectively, transport the positively charged thiamine (vitamin B1) into cells to enable its efficient utilization. SLC19A2 and SLC19A3 are also known to transport structurally unrelated cationic drugs, such as metformin, but whether this charge selectivity extends to other molecules, such as pyridoxine (vitamin B6), is unknown. We tested this possibility using Madin-Darby canine kidney II (MDCKII) cells and human embryonic kidney 293 (HEK293) cells for transfection experiments, and also using Caco-2 cells as human intestinal epithelial model cells. The stable expression of SLC19A2 and SLC19A3 in MDCKII cells (as well as their transient expression in HEK293 cells) led to a significant induction in pyridoxine uptake at pH 5.5 compared with control cells. The induced uptake was pH-dependent, favoring acidic conditions over neutral to basic conditions, and protonophore-sensitive. It was saturable as a function of pyridoxine concentration, with an apparent Km of 37.8 and 18.5 μm, for SLC19A2 and SLC19A3, respectively, and inhibited by the pyridoxine analogs pyridoxal and pyridoxamine as well as thiamine. We also found that silencing the endogenous SLC19A3, but not SLC19A2, of Caco-2 cells with gene-specific siRNAs lead to a significant reduction in carrier-mediated pyridoxine uptake. These results show that SLC19A2 and SLC19A3 are capable of recognizing/transporting pyridoxine, favoring acidic conditions for operation, and suggest a possible role for these transporters in pyridoxine transport mainly in tissues with an acidic environment like the small intestine, which has an acidic surface microclimate.

Communication between individuals via molecules, termed chemosignaling, is widespread among animal and plant species. However, we lack knowledge on the specific functions of the substances involved for most systems. The femoral gland is an organ that secretes a waxy substance involved in chemical communication in lizards. Although the lipids and volatile substances secreted by the femoral glands have been investigated in several biochemical studies, the protein composition and functions of secretions remain completely unknown. Applying a proteomic approach, we provide the first attempt to comprehensively characterize the protein composition of femoral gland secretions from the Galápagos marine iguana. Using samples from several organs, the marine iguana proteome was assembled by next-generation sequencing and MS, resulting in 7513 proteins. Of these, 4305 proteins were present in the femoral gland, including keratins, small serum proteins, and fatty acid-binding proteins. Surprisingly, no proteins with discernible roles in partner recognition or inter-species communication could be identified. However, we did find several proteins with direct associations to the innate immune system, including lysozyme C, antileukoproteinase (ALP), pulmonary surfactant protein (SFTPD), and galectin (LGALS1) suggesting that the femoral glands function as an important barrier to infection. Furthermore, we report several novel anti-microbial peptides from the femoral glands that show similar action against Escherichia coli and Bacillus subtilis such as oncocin, a peptide known for its effectiveness against Gram-negative pathogens. This proteomics data set is a valuable resource for future functional protein analysis and demonstrates that femoral gland secretions also perform functions of the innate immune system.

A key point in achieving accurate intact glycopeptide identification is the definition of the glycan composition file that is used to match experimental with theoretical masses by a glycoproteomics search engine. At present, these files are mainly built from searching the literature and/or querying data sources focused on posttranslational modifications. Most glycoproteomics search engines include a default composition file that is readily used when processing MS data. We introduce here a glycan composition visualizing and comparative tool associated with the GlyConnect database and called GlyConnect Compozitor. It offers a web interface through which the database can be queried to bring out contextual information relative to a set of glycan compositions. The tool takes advantage of compositions being related to one another through shared monosaccharide counts and outputs interactive graphs summarizing information searched in the database. These results provide a guide for selecting or deselecting compositions in a file in order to reflect the context of a study as closely as possible. They also confirm the consistency of a set of compositions based on the content of the GlyConnect database. As part of the tool collection of the Glycomics@ExPASy initiative, Compozitor is hosted at https://glyconnect.expasy.org/compozitor/ where it can be run as a web application. It is also directly accessible from the GlyConnect database.

Co-fractionation MS (CF-MS) is a technique with potential to characterize endogenous and unmanipulated protein complexes on an unprecedented scale. However this potential has been offset by a lack of guidelines for best-practice CF-MS data collection and analysis. To obtain such guidelines, this study thoroughly evaluates novel and published Saccharomyces cerevisiae CF-MS data sets using very high proteome coverage libraries of yeast gold standard complexes. A new method for identifying gold standard complexes in CF-MS data, Reference Complex Profiling, and the Extending 'Guilt-by-Association' by Degree (EGAD) R package are used for these evaluations, which are verified with concurrent analyses of published human data. By evaluating data collection designs, which involve fractionation of cell lysates, it is found that near-maximum recall of complexes can be achieved with fewer samples than published studies. Distributing sample collection across orthogonal fractionation methods, rather than a single high resolution data set, leads to particularly efficient recall. By evaluating 17 different similarity scoring metrics, which are central to CF-MS data analysis, it is found that two metrics rarely used in past CF-MS studies – Spearman and Kendall correlations – and the recently introduced Co-apex metric frequently maximize recall, whereas a popular metric—Euclidean distance—delivers poor recall. The common practice of integrating external genomic data into CF-MS data analysis is also evaluated, revealing that this practice may improve the precision and recall of known complexes but is generally unsuitable for predicting novel complexes in model organisms. If studying nonmodel organisms using orthologous genomic data, it is found that particular subsets of fractionation profiles (e.g. the lowest abundance quartile) should be excluded to minimize false discovery. These assessments are summarized in a series of universally applicable guidelines for precise, sensitive and efficient CF-MS studies of known complexes, and effective predictions of novel complexes for orthogonal experimental validation.

After ejaculation, mammalian spermatozoa must undergo a process known as capacitation in order to successfully fertilize the oocyte. Several post-translational modifications occur during capacitation, including sialylation, which despite being limited to a few proteins, seems to be essential for proper sperm-oocyte interaction. Regardless of its importance, to date, no single study has ever identified nor quantified which glycoproteins bearing terminal sialic acid (Sia) are altered during capacitation. Here we characterize sialylation during mouse sperm capacitation. Using tandem MS coupled with liquid chromatography (LC–MS/MS), we found 142 nonreductant peptides, with 9 of them showing potential modifications on their sialylated oligosaccharides during capacitation. As such, N-linked sialoglycopeptides from C4b-binding protein, endothelial lipase (EL), serine proteases 39 and 52, testis-expressed protein 101 and zonadhesin were reduced following capacitation. In contrast, mitochondrial aconitate hydratase (aconitase; ACO2), a TCA cycle enzyme, was the only protein to show an increase in Sia content during capacitation. Interestingly, although the loss of Sia within EL (N62) was accompanied by a reduction in its phospholipase A₁ activity, a decrease in the activity of ACO2 (i.e. stereospecific isomerization of citrate to isocitrate) occurred when sialylation increased (N612). The latter was confirmed by N612D recombinant protein tagged with both His and GFP. The replacement of Sia for the negatively charged Aspartic acid in the N612D mutant caused complete loss of aconitase activity compared with the WT. Computer modeling show that N612 sits atop the catalytic site of ACO2. The introduction of Sia causes a large conformational change in the alpha helix, essentially, distorting the active site, leading to complete loss of function. These findings suggest that the switch from oxidative phosphorylation, over to glycolysis that occurs during capacitation may come about through sialylation of ACO2.

Amino acid hydroxylation is a common post-translational modification, which generally regulates protein interactions or adds a functional group that can be further modified. Such hydroxylation is currently considered irreversible, necessitating the degradation and re-synthesis of the entire protein to reset the modification. Here we present evidence that the cellular machinery can reverse FIH-mediated asparagine hydroxylation on intact proteins. These data suggest that asparagine hydroxylation is a flexible and dynamic post-translational modification akin to modifications involved in regulating signaling networks, such as phosphorylation, methylation and ubiquitylation.

Despite the crucial function of the small intestine in nutrient uptake our understanding of the molecular events underlying the digestive function is still rudimentary. Recent studies demonstrated that enterocytes do not direct the entire dietary triacylglycerol toward immediate chylomicron synthesis. Especially after high-fat challenges, parts of the resynthesized triacylglycerol are packaged into cytosolic lipid droplets for transient storage in the endothelial layer of the small intestine. The reason for this temporary storage of triacylglycerol is not completely understood. To utilize lipids from cytosolic lipid droplets for chylomicron synthesis in the endoplasmic reticulum, stored triacylglycerol has to be hydrolyzed either by cytosolic lipolysis or lipophagy. Interestingly, triacylglycerol storage and chylomicron secretion rates are unevenly distributed along the small intestine, with the proximal jejunum exhibiting the highest intermittent storage capacity. We hypothesize that correlating hydrolytic enzyme activities with the reported distribution of triacylglycerol storage and chylomicron secretion in different sections of the small intestine is a promising strategy to determine key enzymes in triacylglycerol remobilization. We employed a serine hydrolase specific activity-based labeling approach in combination with quantitative proteomics to identify and rank hydrolases based on their relative activity in 11 sections of the small intestine. Moreover, we identified several clusters of enzymes showing similar activity distribution along the small intestine. Merging our activity-based results with substrate specificity and subcellular localization known from previous studies, carboxylesterase 2e and arylacetamide deacetylase emerge as promising candidates for triacylglycerol mobilization from cytosolic lipid droplets in enterocytes.

The absence of the dystrophin protein in Duchenne muscular dystrophy (DMD) results in myofiber fragility and a plethora of downstream secondary pathologies. Although a variety of experimental therapies are in development, achieving effective treatments for DMD remains exceptionally challenging, not least because the pathological consequences of dystrophin loss are incompletely understood. Here we have performed proteome profiling in tibialis anterior muscles from two murine DMD models (mdx and mdx52) at three ages (8, 16, and 80 weeks of age), all n = 3. High-resolution isoelectric focusing liquid chromatography-tandem MS (HiRIEF-LC–MS/MS) was used to quantify the expression of 4974 proteins across all 27 samples. The two dystrophic models were found to be highly similar, whereas multiple proteins were differentially expressed relative to WT (C57BL/6) controls at each age. Furthermore, 1795 proteins were differentially expressed when samples were pooled across ages and dystrophic strains. These included numerous proteins associated with the extracellular matrix and muscle function that have not been reported previously. Pathway analysis revealed multiple perturbed pathways and predicted upstream regulators, which together are indicative of cross-talk between inflammatory, metabolic, and muscle growth pathways (e.g. TNF, INF, NF-B, SIRT1, AMPK, PGC-1α, PPARs, ILK, and AKT/PI3K). Upregulation of CAV3, MVP and PAK1 protein expression was validated in dystrophic muscle by Western blot. Furthermore, MVP was upregulated during, but not required for, the differentiation of C2C12 myoblasts suggesting that this protein may affect muscle regeneration. This study provides novel insights into mutation-independent proteomic signatures characteristic of the dystrophic phenotype and its progression with aging.

Huanglongbing (HLB) is the most devastating and widespread citrus disease. All commercial citrus varieties are susceptible to the HLB-associated bacterium, Candidatus Liberibacter asiaticus (CLas), which resides in the phloem. The phloem is part of the plant vascular system and is involved in sugar transport. To investigate the plant response to CLas, we enriched for proteins surrounding the phloem in an HLB susceptible sweet orange variety, Washington navel (Citrus sinensis (L) Osbeck). Quantitative proteomics revealed global changes in the citrus proteome after CLas inoculation. Plant metabolism and translation were suppressed, whereas defense-related proteins such as peroxidases, proteases and protease inhibitors were induced in the vasculature. Transcript accumulation and enzymatic activity of plant peroxidases in CLas infected sweet orange varieties under greenhouse and field conditions were assessed. Although peroxidase transcript accumulation was induced in CLas infected sweet orange varieties, peroxidase enzymatic activity varied. Specific serine proteases were up-regulated in Washington navel in the presence of CLas based on quantitative proteomics. Subsequent activity-based protein profiling revealed increased activity of two serine proteases, and reduced activity of one protease in two C. sinensis sweet orange varieties under greenhouse and field conditions. The observations in the current study highlight global reprogramming of the citrus vascular proteome and differential regulation of enzyme classes in response to CLas infection. These results open an avenue for further investigation of diverse responses to HLB across different environmental conditions and citrus genotypes.

L’utilisation du féminin dans les titres de professions dans le domaine de la santé a beaucoup évolué ces dernières années. Cela reflète une prise de conscience croissante de certaines réalités des métiers de la santé et la reconnaissance de la présence de plus en plus importante des femmes dans le domaine. Vous demandez-vous quand mettre les professions au féminin […]

L’article Quand mettre les professions au féminin dans le domaine de la santé ? est apparu en premier sur Ortho Doc France.

Pour beaucoup de personnes, la perte de poids rime obligatoirement avec une période de privation. Mais contrairement à ces idées reçues, il est bien possible d’observer un régime pour perdre du poids tout en vous faisant plaisir. Découvrez notre recette minceur de biscuits croquants sans beurre aux flocons d’avoine qui raviront vos papilles sans pour autant vous apporter […]

L’article Quelle est la meilleure recette minceur à base de biscuits aux flocons d’avoine ? est apparu en premier sur Ortho Doc France.

Protein tyrosine kinases (PTKs) play key roles in cellular signal transduction, cell cycle regulation, cell division, and cell differentiation. Dysregulation of PTK-activated pathways, often by receptor overexpression, gene amplification, or genetic mutation, is a causal factor underlying numerous cancers. In this study, we have developed a parallel reaction monitoring (PRM)-based assay for quantitative profiling of 83 PTKs. The assay detects 308 proteotypic peptides from 54 receptor tyrosine kinases and 29 nonreceptor tyrosine kinases in a single run. Quantitative comparisons were based on the labeled reference peptide method. We implemented the assay in four cell models: 1) a comparison of proliferating versus epidermal growth factor (EGF)-stimulated A431 cells, 2) a comparison of SW480Null (mutant APC) and SW480APC (APC restored) colon tumor cell lines, and 3) a comparison of 10 colorectal cancer cell lines with different genomic abnormalities, and 4) lung cancer cell lines with either susceptibility (11-18) or acquired resistance (11-18R) to the epidermal growth factor receptor tyrosine kinase inhibitor erlotinib. We observed distinct PTK expression changes that were induced by stimuli, genomic features or drug resistance, which were consistent with previous reports. However, most of the measured expression differences were novel observations. For example, acquired resistance to erlotinib in the 11-18 cell model was associated not only with previously reported upregulation of MET, but also with upregulation of FLK2 and downregulation of LYN and PTK7. Immunoblot analyses and shotgun proteomics data were highly consistent with PRM data. Multiplexed PRM assays provide a targeted, systems-level profiling approach to evaluate cancer-related proteotypes and adaptations. Data are available through Proteome eXchange Accession PXD002706.

O-GlcNAcylation, the addition of a single N-acetylglucosamine residue to serine and threonine residues of cytoplasmic, nuclear, or mitochondrial proteins, is a widespread regulatory post-translational modification. It is involved in response to nutritional status and stress and its dysregulation is associated with diseases ranging from Alzheimer’s to diabetes.  While the modification was first detected over thirty-five years ago, research into the function of O-GlcNAcylation has accelerated dramatically in the last ten years due to the development of new enrichment and mass spectrometry techniques that facilitate its analysis.  This article summarizes methods for O-GlcNAc enrichment, key mass spectrometry instrumentation advancements, particularly those that allow modification site localization, and software tools that allow analysis of data from O-GlcNAc modified peptides.

Sparkling wine is an alcoholic beverage enjoyed around the world. The sensory properties of sparkling wine depend on a complex interplay between the chemical and biochemical components in the final product. Glycoproteins have been linked to positive and negative qualities in sparkling wine, but the glycosylation profiles of sparkling wine have not been previously investigated in detail. We analysed the glyco/proteome of sparkling wines using protein- and glycopeptide-centric approaches. We developed an automated workflow that created ion libraries to analyse Sequential Window Acquisition of all THeoretical mass spectra (SWATH) Data Independent Acquisition (DIA) mass spectrometry data based on glycopeptides identified by Byonic. We applied our workflow to three pairs of experimental sparkling wines to assess the effects of aging on lees and of different yeast strains used in the Liqueur de Tirage for secondary fermentation. We found that aging a cuvée on lees for 24 months compared to 8 months led to a dramatic decrease in overall protein abundance and an enrichment in large glycans at specific sites in some proteins. Secondary fermentation of a Riesling wine with Saccharomyces cerevisiae yeast strain Siha4 produced more yeast proteins and glycoproteins than with S. cerevisiae yeast strain DV10. The abundance and glycosylation profiles of grape glycoproteins were also different between grape varieties. This work represents the first in-depth study into protein- and peptide-specific glycosylation in sparkling wines and describes a quantitative glycoproteomic SWATH/DIA workflow that is broadly applicable to other sample types.

Esophageal squamous cell cancer (ESCC) is an aggressive malignancy with poor therapeutic outcomes. However, the alterations in proteins and post-translational modifications (PTMs) leading to the pathogenesis of ESCC remains unclear. Here, we provide the comprehensive characterization of the proteome, phosphorylome, lysine acetylome and succinylome for ESCC and matched control cells using quantitative proteomic approach. We identify abnormal protein and post-translational modification (PTM) pathways, including significantly downregulated lysine succinylation sites in cancer cells. Focusing on hyposuccinylation, we reveal that this altered PTM was enriched on enzymes of metabolic pathways inextricably linked with cancer metabolism. Importantly, ESCC malignant behaviors such as cell migration are inhibited once the level of succinylation was restored in vitro or in vivo. This effect was further verified by mutations to disrupt succinylation sites in candidate proteins. Meanwhile, we found that succinylation has a negative regulatory effect on histone methylation to promote cancer migration. Finally, hyposuccinylation is confirmed in primary ESCC specimens. Our findings together demonstrate that lysine succinylation may alter ESCC metabolism and migration, providing new insights into the functional significance of PTM in cancer biology.

Thyroglobulin (Tg) is a secreted iodoglycoprotein serving as the precursor for T3 and T4 hormones. Many characterized Tg gene mutations produce secretion-defective variants resulting in congenital hypothyroidism (CH). Tg processing and secretion is controlled by extensive interactions with chaperone, trafficking, and degradation factors comprising the secretory proteostasis network. While dependencies on individual proteostasis network components are known, the integration of proteostasis pathways mediating Tg protein quality control and the molecular basis of mutant Tg misprocessing remain poorly understood. We employ a multiplexed quantitative affinity purification–mass spectrometry approach to define the Tg proteostasis interactome and changes between WT and several CH-variants. Mutant Tg processing is associated with common imbalances in proteostasis engagement including increased chaperoning, oxidative folding, and engagement by targeting factors for ER-associated degradation (ERAD). Furthermore, we reveal mutation-specific changes in engagement with N-glycosylation components, suggesting distinct requirements for one Tg variant on dual engagement of both oligosaccharyltransferase complex isoforms for degradation. Modulating dysregulated proteostasis components and pathways may serve as a therapeutic strategy to restore Tg secretion and thyroid hormone biosynthesis.

The early detection of pancreatic ductal adenocarcinoma is a complex clinical obstacle yet is key to improving the overall likelihood of patient survival. Current and prospective carbohydrate biomarkers CA19-9 and sTRA are sufficient for surveilling disease progression yet are not approved for delineating PDAC from other abdominal cancers and non-cancerous pancreatic pathologies. To further understand these glycan epitopes, an imaging mass spectrometry approach was utilized to assess the N-glycome of the human pancreas and pancreatic cancer in a cohort of PDAC patients represented by tissue microarrays and whole tissue sections. Orthogonally, these same tissues were characterized by multi-round immunofluorescence which defined expression of CA19-9 and sTRA as well as other lectins towards carbohydrate epitopes with the potential to improve PDAC diagnosis. These analyses revealed distinct differences not only in N-glycan spatial localization across both healthy and diseased tissues but importantly between different biomarker-categorized tissue samples. Unique sulfated bi-antennary N-glycans were detected specifically in normal pancreatic islets. N-glycans from CA19-9 expressing tissues tended to be bi-, tri- and tetra-antennary structures with both core and terminal fucose residues and bisecting N-acetylglucosamines. These N-glycans were detected in less abundance in sTRA-expressing tumor tissues, which favored tri- and tetra-antennary structures with polylactosamine extensions. Increased sialylation of N-glycans was detected in all tumor tissues. A candidate new biomarker derived from IMS was further explored by fluorescence staining with selected lectins on the same tissues. The lectins confirmed the expression of the epitopes in cancer cells and revealed different tumor-associated staining patterns between glycans with bisecting GlcNAc and those with terminal GlcNAc. Thus, the combination of lectin-IHC and IMS techniques produces more complete information for tumor classification than the individual analyses alone. These findings potentiate the development of early assessment technologies to rapidly and specifically identify PDAC in the clinic that may directly impact patient outcomes.

The approach of peptide-based anti-cancer vaccination has proven the ability to induce cancer-specific immune responses in multiple studies for various cancer entities. However, clinical responses remain so far limited to single patients and broad clinical applicability was not achieved. Therefore, further efforts are required to improve peptide vaccination in order to integrate this low side effect therapy into the clinical routine of cancer therapy. To design clinically effective peptide vaccines in the future, different issues have to be addressed and optimized comprising antigen target selection as well as choice of optimal adjuvants and vaccination schedules. Furthermore, the combination of peptide-based vaccines with other immuno- and molecular targeted therapies as well as the development of predictive biomarkers could further improve efficacy. In this review, current approaches in the development of peptide-based vaccines and critical implications for optimal vaccine design are discussed.

Deep proteome coverage in bottom-up proteomics requires peptide-level fractionation to simplify the complex peptide mixture before analysis by tandem mass spectrometry. By decreasing the number of co-eluting precursor peptide ions, fractionation effectively reduces the complexity of the sample leading to higher sample coverage and reduced bias towards high abundance precursors that are preferentially identified in data-dependent acquisition strategies. To achieve this goal, we report a bead-based off-line peptide fractionation method termed CIF or Carboxylate modified magnetic bead-based isopropanol gradient peptide fractionation. CIF is an extension of the SP3 (single-pot solid-phase-enhanced sample preparation) strategy and provides an effective but complementary approach to other commonly used fractionation methods including strong cation exchange (SCX) and reversed phase (RP)-based chromatography. We demonstrate that CIF is an effective offline separation strategy capable of increasing the depth of peptide analyte coverage both when used alone or as a second dimension of peptide fractionation in conjunction with high pH RP. These features make it ideally suited for a wide range of proteomic applications including the affinity purification of low abundance bait proteins.

Cells continually degrade and replace damaged proteins. However, the high energetic demand of protein turnover generates reactive oxygen species (ROS) that compromise the long-term health of the proteome. Thus, the relationship between aging, protein turnover and energetic demand remains unclear. Here, we used a proteomic approach to measure rates of protein turnover within primary fibroblasts isolated from a number of species with diverse lifespans including the longest-lived mammal, the bowhead whale. We show that organismal lifespan is negatively correlated with turnover rates of highly abundant proteins. In comparison to mice, cells from long-lived naked mole rats have slower rates of protein turnover, lower levels of ATP production and reduced ROS levels. Despite having slower rates of protein turnover, naked mole rat cells tolerate protein misfolding stress more effectively than mouse cells. We suggest that in lieu of rapid constitutive turnover, long-lived species may have evolved more energetically efficient mechanisms for selective detection and clearance of damaged proteins.

Giardia lamblia (G. lamblia) disease is a zoonosis with a-infection rate affecting the general population of the world. Despite the constant possibility of damage due to their own metabolism, G. lamblia have survived and evolved to adapt to various environments. However, research on energy-metabolism conversion in G. lamblia is limited. This study aimed to reveal the dynamic metabolism-conversion mechanism in G. lamblia under sugar starvation by detecting global lysine acetylation and 2-hydroxyisobutyrylation sites combined with quantitative proteome analyses. A total of 2999 acetylation sites on 956 proteins and 8877 2-hydroxyisobutyryl sites on 1546 proteins were quantified under sugar starvation. Integrated Kac and Khib data revealed that modified proteins were associated with arginine biosynthesis, glycolysis/gluconeogenesis, and alanine, aspartate, and glutamate metabolism. These findings suggested that lysine acetylation and 2-hydroxyisobutyrylation were ubiquitous and provided deep insight into the metabolism-conversion mechanism in G. lamblia under sugar starvation. Overall, these results can help understand the biology of G. lamblia infections and reveal the evolution rule from prokaryote to eukaryote.

Exploring Public International Law and the Rights of Individuals with Chinese Scholars - Part One Other resource sysadmin 29 October 2018

As part of a roundtable series, Chatham House and China University of Political Science and Law (CUPL) jointly organized this four-day meeting at Chatham House for international lawyers to discuss a wide range of issues related to public international law and the rights of individuals.

The specific objectives were to:

• create a platform for Chinese international law academics working on international human rights law issues to present their thinking and exchange ideas with counterparts from outside China;
• build stronger understanding within the wider international law community of intellectual debates taking place in China about the international human rights system and China’s role within it;
• support networking between Chinese and non-Chinese academics working on international human rights and related areas of international law.

The roundtable forms part of a wider Chatham House project exploring China’s impact on the international human rights system and was inspired by early discussions with a burgeoning community of Chinese academics thinking, writing (mainly in Chinese) and teaching about international human rights law.

For China University of Political Science and Law, one of the largest and most prestigious law schools in China and perhaps the only university in the world with an entire faculty of international law, the initiative is part of a drive to forge partnerships beyond China in the international law field.

The roundtable had a total of 22 participants, 10 Chinese (from universities and other academic institutions in Beijing and Shanghai) and 12 non-Chinese (from Australia, Germany, the Netherlands, Switzerland, the United Kingdom and the United States).

All discussions were held in English under the Chatham House Rule.

Exploring Public International Law and the Rights of Individuals with Chinese Scholars - Part Two Other resource sysadmin 30 October 2018

As part of a roundtable series, Chatham House and China University of Political Science and Law (CUPL) held a two-day roundtable meeting in Beijing on public international law and the rights of individuals.

The specific objectives were to:

• create a platform for Chinese international law academics working on international human rights law issues to present their thinking and exchange ideas with counterparts from outside China;
• build stronger understanding within the wider international law community of intellectual debates taking place in China about the international human rights system and China’s role within it;
• support networking between Chinese and non-Chinese academics working on international human rights and related areas of international law.

The roundtable forms part of a wider Chatham House project exploring China’s impact on the international human rights system and was inspired by early discussions with a burgeoning community of Chinese academics thinking, writing (mainly in Chinese) and teaching about international human rights law.

For CUPL, one of the largest and most prestigious law schools in China and perhaps the only university in the world with an entire faculty of international law, the initiative is part of a drive to forge partnerships beyond China in the international law field.

The meeting in Beijing was hosted by CUPL and involved 20 participants, 10 Chinese (from universities and other academic institutions in Beijing) and 10 non-Chinese (from Australia, the Netherlands, South Africa, Switzerland, the United Kingdom and the United States).

To ensure continuity while also expanding the experts network being built, the second meeting included a mix of participants from the first meeting and some new participants.

All discussions were held in English under the Chatham House Rule.

Exploring Public International Law and the Rights of Individuals with Chinese Scholars - Part Three Other resource sysadmin 30 October 2018

As part of a roundtable series, Chatham House, China University of Political Science and Law (CUPL) and the Graduate Institute Geneva held a two-day roundtable meeting in Geneva on public international law and the rights of individuals.

The specific objectives were to:

• create a platform for Chinese international law academics working on international human rights law issues to present their thinking and exchange ideas with counterparts from outside China;
• build stronger understanding within the wider international law community of intellectual debates taking place in China about the international human rights system and China’s role within it;
• support networking between Chinese and non-Chinese academics working on international human rights and related areas of international law.

The roundtable forms part of a wider Chatham House project exploring China’s impact on the international human rights system and was inspired by early discussions with a burgeoning community of Chinese academics thinking, writing (mainly in Chinese) and teaching about international human rights law.

For CUPL, one of the largest and most prestigious law schools in China and perhaps the only university in the world with an entire faculty of international law, the initiative is part of a drive to forge partnerships beyond China in the international law field.

The meeting in Geneva was co-hosted by the Graduate Institute Geneva and involved 19 participants, 9 Chinese (from six research institutions in Beijing and Shanghai) and 11 non-Chinese (from eight research institutions in Australia, Germany, the Netherlands, Switzerland, the United Kingdom and the United States).

To ensure continuity while also expanding the expert network being built, the third meeting included a mix of participants from the first two meetings and some new participants

All discussions were held in English under the Chatham House Rule.

Exploring Public International Law Issues with Chinese Scholars – Part Four Other resource sysadmin 30 October 2018

As part of a roundtable series, Chatham House and the China University of Political Science and Law (CUPL) held a two-day roundtable in Beijing on emerging issues of public international law.

The specific objectives were to:

• create a platform for Chinese international law academics working on international human rights law issues to present their thinking and exchange ideas with counterparts from outside China;
• build stronger understanding within the wider international law community of intellectual debates taking place in China about the international human rights system and China’s role within it;
• support networking between Chinese and non-Chinese academics working on international human rights and related areas of international law.

The roundtable forms part of a wider Chatham House project exploring China’s impact on the international human rights system and was inspired by early discussions with a burgeoning community of Chinese academics thinking, writing (mainly in Chinese) and teaching about international human rights law.

For CUPL, one of the largest and most prestigious law schools in China and perhaps the only university in the world with an entire faculty of international law, the initiative is part of a drive to forge partnerships beyond China in the international law field.

The meeting was co-hosted with CUPL and involved 28 participants, consisting of 19 Chinese participants (from six leading research institutions in Beijing and Shanghai) and nine nonChinese participants (from eight leading research institutions in Australia, the Netherlands, the UK, Switzerland, Canada and Singapore).

To ensure continuity while also expanding the expert network being built, the fifth meeting included a mix of participants from the previous meetings and some new participants.

All discussions were held in English under the Chatham House Rule.

Online Disinformation and Political Discourse: Applying a Human Rights Framework Research paper sysadmin 5 November 2019

Although some digital platforms now have an impact on more people’s lives than does any one state authority, the international community has been slow to hold to account these platforms’ activities by reference to human rights law.

This paper examines how human rights frameworks should guide digital technology.

Summary

• Online political campaigning techniques are distorting our democratic political processes. These techniques include the creation of disinformation and divisive content; exploiting digital platforms’ algorithms, and using bots, cyborgs and fake accounts to distribute this content; maximizing influence through harnessing emotional responses such as anger and disgust; and micro-targeting on the basis of collated personal data and sophisticated psychological profiling techniques. Some state authorities distort political debate by restricting, filtering, shutting down or censoring online networks.
• Such techniques have outpaced regulatory initiatives and, save in egregious cases such as shutdown of networks, there is no international consensus on how they should be tackled. Digital platforms, driven by their commercial impetus to encourage users to spend as long as possible on them and to attract advertisers, may provide an environment conducive to manipulative techniques.
• International human rights law, with its careful calibrations designed to protect individuals from abuse of power by authority, provides a normative framework that should underpin responses to online disinformation and distortion of political debate. Contrary to popular view, it does not entail that there should be no control of the online environment; rather, controls should balance the interests at stake appropriately.
• The rights to freedom of thought and opinion are critical to delimiting the appropriate boundary between legitimate influence and illegitimate manipulation. When digital platforms exploit decision-making biases in prioritizing bad news and divisive, emotion-arousing information, they may be breaching these rights. States and digital platforms should consider structural changes to digital platforms to ensure that methods of online political discourse respect personal agency and prevent the use of sophisticated manipulative techniques.
• The right to privacy includes a right to choose not to divulge your personal information, and a right to opt out of trading in and profiling on the basis of your personal data. Current practices in collecting, trading and using extensive personal data to ‘micro-target’ voters without their knowledge are not consistent with this right. Significant changes are needed.
• Data protection laws should be implemented robustly, and should not legitimate extensive harvesting of personal data on the basis of either notional ‘consent’ or the data handler’s commercial interests. The right to privacy should be embedded in technological design (such as by allowing the user to access all information held on them at the click of a button); and political parties should be transparent in their collection and use of personal data, and in their targeting of messages. Arguably, the value of personal data should be shared with the individuals from whom it derives.
• The rules on the boundaries of permissible content online should be set by states, and should be consistent with the right to freedom of expression. Digital platforms have had to rapidly develop policies on retention or removal of content, but those policies do not necessarily reflect the right to freedom of expression, and platforms are currently not well placed to take account of the public interest. Platforms should be far more transparent in their content regulation policies and decision-making, and should develop frameworks enabling efficient, fair, consistent internal complaints and content monitoring processes. Expertise on international human rights law should be integral to their systems.
• The right to participate in public affairs and to vote includes the right to engage in public debate. States and digital platforms should ensure an environment in which all can participate in debate online and are not discouraged from standing for election, from participating or from voting by online threats or abuse.

War Time: Temporality and the Decline of Western Military Power Book dora.popova 22 February 2021

In War Time the Western way of war, its pace and timing, are discussed and analysed by experts who question the West’s ability to maintain its military superiority given the political and strategic failures of interventions in Iraq and Afghanistan.

In War Time, war studies experts examine the trajectory of Western military power. They discuss conflicting perceptions of time anchored within Western political and military institutions, and the Western attachment to fast-paced warfare at the expense of longer-term political solutions.

Divided into three sections, the book covers ‘civic militarism’ and the trajectory of Western power, Western perceptions of time and the international normative order, and military operations and temporality. War Time explains why the West has been overwhelmingly powerful on the battlefield and yet strategically and politically weak as exemplified by the return of the Taliban and the hasty evacuation of troops and personnel from Afghanistan.

The book identifies policies that decision-makers must adopt to stave off the decline of Western military dominance.

This book is part of the Insights series.

Watch the event

A special event was held in March 2021 to mark the launch of the book. View the event here.

Praise for War Time

About the editors

Sten Rynning is professor of war studies at the University of Southern Denmark.

Olivier Schmitt is professor with special responsibilities at the Center for War Studies, University of Southern Denmark, and currently director of research and studies at the French Institute for Higher National Defence Studies.

Amelie Theussen is assistant professor at the Center for War Studies, University of 
Southern Denmark.

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The faithful segregation, or “partition,” of many low-copy number bacterial plasmids is driven by plasmid-encoded ATPases that are represented by the P1 plasmid ParA protein. ParA binds to the bacterial nucleoid via an ATP-dependent nonspecific DNA (nsDNA)-binding activity, which is essential for partition. ParA also has a site-specific DNA-binding activity to the par operator (parOP), which requires either ATP or ADP, and which is essential for it to act as a transcriptional repressor but is dispensable for partition. Here we examine how DNA binding by ParA contributes to the relative distribution of its plasmid partition and repressor activities, using a ParA with an alanine substitution at Arg351, a residue previously predicted to participate in site-specific DNA binding. In vivo, the parAR351A allele is compromised for partition, but its repressor activity is dramatically improved so that it behaves as a “super-repressor.” In vitro, ParAR351A binds and hydrolyzes ATP, and undergoes a specific conformational change required for nsDNA binding, but its nsDNA-binding activity is significantly damaged. This defect in turn significantly reduces the assembly and stability of partition complexes formed by the interaction of ParA with ParB, the centromere-binding protein, and DNA. In contrast, the R351A change shows only a mild defect in site-specific DNA binding. We conclude that the partition defect is due to altered nsDNA binding kinetics and affinity for the bacterial chromosome. Furthermore, the super-repressor phenotype is explained by an increased pool of non-nucleoid bound ParA that is competent to bind parOP and repress transcription.

In eukaryotic DNA replication, DNA polymerase ε (Polε) is responsible for leading strand synthesis, whereas DNA polymerases α and δ synthesize the lagging strand. The human Polε (hPolε) holoenzyme is comprised of the catalytic p261 subunit and the noncatalytic p59, p17, and p12 small subunits. So far, the contribution of the noncatalytic subunits to hPolε function is not well understood. Using pre-steady-state kinetic methods, we established a minimal kinetic mechanism for DNA polymerization and editing catalyzed by the hPolε holoenzyme. Compared with the 140-kDa N-terminal catalytic fragment of p261 (p261N), which we kinetically characterized in our earlier studies, the presence of the p261 C-terminal domain (p261C) and the three small subunits increased the DNA binding affinity and the base substitution fidelity. Although the small subunits enhanced correct nucleotide incorporation efficiency, there was a wide range of rate constants when incorporating a correct nucleotide over a single-base mismatch. Surprisingly, the 3'→5' exonuclease activity of the hPolε holoenzyme was significantly slower than that of p261N when editing both matched and mismatched DNA substrates. This suggests that the presence of p261C and the three small subunits regulates the 3'→5' exonuclease activity of the hPolε holoenzyme. Together, the 3'→5' exonuclease activity and the variable mismatch extension activity modulate the overall fidelity of the hPolε holoenzyme by up to 3 orders of magnitude. Thus, the presence of p261C and the three noncatalytic subunits optimizes the dual enzymatic activities of the catalytic p261 subunit and makes the hPolε holoenzyme an efficient and faithful replicative DNA polymerase.

The origin recognition complex (ORC), composed of six subunits, ORC1–6, binds to origins of replication as a ring-shaped heterohexameric ATPase that is believed to be essential to recruit and load MCM2–7, the minichromosome maintenance protein complex, around DNA and initiate DNA replication. We previously reported the creation of viable cancer cell lines that lacked detectable ORC1 or ORC2 protein without a reduction in the number of origins firing. Here, using CRISPR-Cas9–mediated mutations, we report that human HCT116 colon cancer cells also survive when ORC5 protein expression is abolished via a mutation in the initiator ATG of the ORC5 gene. Even if an internal methionine is used to produce an undetectable, N terminally deleted ORC5, the protein would lack 80% of the AAA+ ATPase domain, including the Walker A motif. The ORC5-depleted cells show normal chromatin binding of MCM2–7 and initiate replication from a similar number of origins as WT cells. In addition, we introduced a second mutation in ORC2 in the ORC5 mutant cells, rendering both ORC5 and ORC2 proteins undetectable in the same cells and destabilizing the ORC1, ORC3, and ORC4 proteins. Yet the double mutant cells grow, recruit MCM2–7 normally to chromatin, and initiate DNA replication with normal number of origins. Thus, in these selected cancer cells, either a crippled ORC lacking ORC2 and ORC5 and present at minimal levels on the chromatin can recruit and load enough MCM2–7 to initiate DNA replication, or human cell lines can sometimes recruit MCM2–7 to origins independent of ORC.

Cesar Hernandez scored 91 runs last season, the Phillies' highest mark since Rollins scored 102 in 2012. Now the luster is no longer there for players who score 100 runs or post 100 RBIs, but Hernandez should score at least 100 runs this season, if he stays healthy and if the Phillies' offense improves as expected.

Business Development in Madagascar: How to Enable Entrepreneurialism 15 November 2017 — 12:00PM TO 1:00PM Anonymous (not verified) 9 November 2017 Chatham House, London

South Africa Needs a Strategic Vision for Its Continent Expert comment sysadmin 24 November 2017

South Africa has the potential to catalyse growth across its sub-region and the continent, but the government must develop a comprehensive strategy that aligns political, ideological and commercial interests.

South Africa’s status as the ‘gateway to Africa’ is under serious threat. Its companies continue to flourish, but complex relationships at home and abroad constrain government capacity to match its economic dominance with political reach and influence.

South Africa’s policies towards the rest of the continent are often accused of being inconsistent and incoherent. It has been a development partner to the region and to international donors; a moral leader, championing human rights and exporting its own model of transition; and an advocate and representative for the continent in international forums. However, it has simultaneously been accused of exploiting its economic dominance at the expense of its neighbours; handicapped by the political debts owed by the ANC to other liberation movements for their assistance in the struggle; and criticized for its arrogance in seeking to position itself as the ‘legitimate’ voice of Africa.

At the same time, reputational risks, a weakened policy environment and poor growth have taken the shine off South Africa’s ‘Gateway to Africa’ rhetoric. South Africa faces considerable domestic economic issues. Growth forecasts have fallen from 1.3 to 0.7 per cent, State owned enterprises are a huge burden on the treasury, and the forecast budget deficit is R50.8 billion (£2.7 billion), at a time when the cost of borrowing is increasing following downgrades of the country’s credit ratings.

Political risk is high, lowering investor confidence. Corruption, poor service delivery and the government’s under-delivery on citizen’s expectations are exacerbating social tensions in a country with expanded unemployment at 36.4 per cent, and one of the highest rates of inequality in the world. McKinsey, KPMG and HSBC have all become entangled in scandal relating to their dealings with government entities that have become ‘captured’ by private interests.

Despite these concerns, South Africa nonetheless remains the backbone of the regional economy, and its firms are key players across the continent. Johannesburg hosts the deepest and most sophisticated capital market on the continent, and Pretoria has one of the highest numbers of diplomatic missions in the world. ESKOM provides around 75 per cent of the electricity contribution to the Southern Africa SADC Power pool – comprising 12 countries, including those as far north as DRC and Tanzania – and South African ports facilitate over half of sub-Saharan Africa’s non-commodity trade with the rest of the world.

Post-apartheid expansion across the continent by South African companies was initially met with resistance, but these relationships have improved significantly – and South African firms retain significant advantages. South African retailers have the scale to incorporate regional producers into continental supply chains, purchasing fresh produce at a competitive price from regional agri-businesses, then re-selling further afield. For example, Zambeef supplies meat from Zambia to Shoprite stores in west Africa.

African companies in turn rely on South Africa as a significant consumer of goods, services and primary commodities. A South African government agreement with the DRC to import about half of the electricity that will be produced by a new grand-scale hydro-power project guaranteed its bankability. Mozambique is looking to maximize the potential of its world-class natural gas reserves by building a pipeline into South Africa, thus benefitting from the purchasing power of South African parastatal electricity utility firm ESKOM.

But South Africa’s status as an economic hegemon is not mirrored in its political relationships. South Africa’s GDP is five times higher than the six countries with which it shares a border, combined. But successive ANC governments have been unable to fully flex this economic muscle. Partly this is a legacy of history. It is not forgotten that the regional economic body, the Southern African Development Community, originated as the organization of Front Line States coordinating efforts to end apartheid, and ZANU-PF officials in Zimbabwe lecture their ANC counterparts on liberation.

The pan-African vision of former president Thabo Mbeki, and promotion of South Africa’s transition as a model for the continent, reflected the values that have driven ANC policy since the end of apartheid. But the coherence of South Africa’s foreign policy has been undermined by conflict and contradiction within the government. Appetite for engagement in Africa is dwindling. The country’s ability to project military influence across the continent is in critical decline. Jacob Zuma’s use of regional political bodies as a means of removing political rivals from domestic politics has corroded goodwill.

A new Africa Programme research paper argues that a fresh approach to South African engagement on the continent is both possible and necessary. South Africa can use its relative economic weight to play a stronger developmental role, leveraging the strengths of its business sector and its financial agencies. But it must match this with stronger and more cooperative political engagement, particularly through cultivating relationships with pivotal states such as Nigeria, Kenya, Ethiopia and Angola.

In December, the ANC will elect a new leader to take the party into elections in 2019. Both leading candidates have international experience – Nkosazana Dlamini-Zuma was the chair of the African Union, and Cyril Ramaphosa has led regional responses to crises in South Sudan, Lesotho and Burundi. South Africa still has considerable foreign policy resources at its disposal. A new strategic vision for Africa that unites the interests of government and business, both domestically and in partner states, can deliver prosperity for both South Africa and the region – and need not contradict the values that have shaped South Africa’s aspirations for the continent in the post-apartheid era.

Mine Action in Angola: Clearing the Legacies of Conflict to Harness the Potential of Peace Other resource sysadmin 14 June 2019

This publication draws on and updates the briefing note published following a meeting of the All- Party Parliamentary Group (APPG) on Angola on 26 April 2017. It also incorporates insights from a Chatham House Africa Programme conference session on the legacies of the Angolan Civil War, held on 23 March 2018; and draws on the Africa Programme’s research into conservation-driven development models in Southern Africa.

Almost two decades after the end of its civil war, Angola remains one of the most heavily landmine-contaminated countries in the world. The Angolan government has committed to clearing its landmines by 2025, and there is constructive collaboration between the government and mine clearing agencies in this endeavour, but the target will be achievable only if a decline in funding from international donors is reversed. International funding for mine clearance in Angola fell by more than 80 per cent between 2005 and 2017, and this sharp drop in external support has compounded the impact on domestic funding for national clearance efforts as a result of the downturn in prices for Angola’s main export commodities.

The national mine action agency, the Comissão Nacional Intersectorial de Desminagem e Assistência Humanitária (CNIDAH), is supported by the Mines Advisory Group (MAG), Norwegian People’s Aid (NPA) and the HALO Trust. By 2017, 15 years after the end of the civil war, these organizations had collectively helped clear 56 per cent of known landmine-contaminated land. State-led demining has focused principally on clearing areas designated for infrastructure projects. Now, it is critical that humanitarian demining in largely agricultural and conservation areas is prioritized to bring to an end the daily threat to Angola’s rural poor – as well as to the country’s livestock and wildlife – of injury or death as a result of landmine accidents.

Angola has some of the world’s most important remaining wilderness, including the tributary system for the unique Okavango Delta, and the country has the potential to host one of the most diverse wildlife populations on the continent. However, the presence of landmines and other remnants of the civil war render large areas of the country unsafe both for wildlife and for the local people, whose ability to derive a sustainable livelihood from their natural environment is fundamental to its protection.

Wildlife and tourism provide important economic opportunities for diversification beyond an oil-dominated economy. Critically, Angola’s economic diversification and development objectives can only be achieved if the landmines that prohibit access to land for agriculture, mining, tourism and wildlife are cleared.

There are economic opportunities for released land in the most heavily mined provinces of Cuando Cubango and Moxico. Already, some new funding for mine action in Angola, if upscaled or matched by international donors, could be transformative for its people, and for the conservation of the region’s vital biodiversity.