Despite its major importance in human health, the metabolic potential of the human gut microbiota is still poorly understood. We have recently shown that biosynthesis of Ruminococcin C (RumC), a novel ribosomally synthesized and posttranslationally modified peptide (RiPP) produced by the commensal bacterium Ruminococcus gnavus, requires two radical SAM enzymes (RumMC1 and RumMC2) catalyzing the formation of four Cα-thioether bridges. These bridges, which are essential for RumC's antibiotic properties against human pathogens such as Clostridium perfringens, define two hairpin domains giving this sactipeptide (sulfur-to-α-carbon thioether–containing peptide) an unusual architecture among natural products. We report here the biochemical and spectroscopic characterizations of RumMC2. EPR spectroscopy and mutagenesis data support that RumMC2 is a member of the large family of SPASM domain radical SAM enzymes characterized by the presence of three [4Fe-4S] clusters. We also demonstrate that this enzyme initiates its reaction by Cα H-atom abstraction and is able to catalyze the formation of nonnatural thioether bonds in engineered peptide substrates. Unexpectedly, our data support the formation of a ketoimine rather than an α,β-dehydro-amino acid intermediate during Cα-thioether bridge LC–MS/MS fragmentation. Finally, we explored the roles of the leader peptide and of the RiPP precursor peptide recognition element, present in myriad RiPP-modifying enzymes. Collectively, our data support a more complex role for the peptide recognition element and the core peptide for the installation of posttranslational modifications in RiPPs than previously anticipated and suggest a possible reaction intermediate for thioether bond formation.

Is there an end to the Central Bank of Libya crisis? 14 November 2024 — 3:00PM TO 4:00PM Anonymous (not verified) 6 November 2024 Online

Experts discuss implications for Libya’s economic governance.

In August this year, the Libyan Presidency Council moved to replace Libya’s longtime central bank governor, Sadiq al-Kabir. Kabir had been in position since September 2011, and in the period following the administrative division of Libya, he rose to prominence as one of the most influential figures on the Libyan political scene.

In the absence of a functioning relationship between executive and legislature, the Central Bank of Libya (CBL) took on many of the competencies of the ministry of finance and became an arbiter of which payments were made and when. In October, following UN-led and parallel back-channel negotiations, a new governor was selected and the CBL board of directors reconstituted.

In this webinar, experts will examine:

• What challenges will the new CBL leadership face?
• Can we expect significant changes for Libya’s economic governance?
• What are the implications for the balance of power between Libya’s rival power centres?

This webinar is organized in partnership with the North Africa Initiative (NAI) at the Foreign Policy Institute (FPI) of the Johns Hopkins Paul H. Nitze School of Advanced International Studies.

James M. Ntambi
Sep 1, 1999; 40:1549-1558
Reviews

David A. Mitchell
Jun 1, 2006; 47:1118-1127
Thematic Reviews

M. Burstein
Nov 1, 1970; 11:583-595
Articles

James E. Balmer
Nov 1, 2002; 43:1773-1808
Reviews

Vitali Matyash
May 1, 2008; 49:1137-1146
Methods

Jason M. Ridlon
Feb 1, 2006; 47:241-259
Reviews

JE Hixson
Mar 1, 1990; 31:545-548
Articles

Expert

Histone recognition by “reader” modules serves as a fundamental mechanism in epigenetic regulation. Previous studies have shown that Spindlin1 is a reader of histone H3K4me3 as well as “K4me3-R8me2a” and promotes transcription of rDNA or Wnt/TCF4 target genes. Here we show that Spindlin1 also acts as a potent reader of histone H3 “K4me3-K9me3/2” bivalent methylation pattern. Calorimetric titration revealed a binding affinity of 16 nm between Spindlin1 and H3 “K4me3-K9me3” peptide, which is one to three orders of magnitude stronger than most other histone readout events at peptide level. Structural studies revealed concurrent recognition of H3K4me3 and H3K9me3/2 by aromatic pockets 2 and 1 of Spindlin1, respectively. Epigenomic profiling studies showed that Spindlin1 colocalizes with both H3K4me3 and H3K9me3 peaks in a subset of genes enriched in biological processes of transcription and its regulation. Moreover, the distribution of Spindlin1 peaks is primarily associated with H3K4me3 but not H3K9me3, which suggests that Spindlin1 is a downstream effector of H3K4me3 generated in heterochromatic regions. Collectively, our work calls attention to an intriguing function of Spindlin1 as a potent H3 “K4me3-K9me3/2” bivalent mark reader, thereby balancing gene expression and silencing in H3K9me3/2-enriched regions.

Phospholipase Cε (PLCε) is activated downstream of G protein–coupled receptors and receptor tyrosine kinases through direct interactions with small GTPases, including Rap1A and Ras. Although Ras has been reported to allosterically activate the lipase, it is not known whether Rap1A has the same ability or what its molecular mechanism might be. Rap1A activates PLCε in response to the stimulation of β-adrenergic receptors, translocating the complex to the perinuclear membrane. Because the C-terminal Ras association (RA2) domain of PLCε was proposed to the primary binding site for Rap1A, we first confirmed using purified proteins that the RA2 domain is indeed essential for activation by Rap1A. However, we also showed that the PLCε pleckstrin homology (PH) domain and first two EF hands (EF1/2) are required for Rap1A activation and identified hydrophobic residues on the surface of the RA2 domain that are also necessary. Small-angle X-ray scattering showed that Rap1A binding induces and stabilizes discrete conformational states in PLCε variants that can be activated by the GTPase. These data, together with the recent structure of a catalytically active fragment of PLCε, provide the first evidence that Rap1A, and by extension Ras, allosterically activate the lipase by promoting and stabilizing interactions between the RA2 domain and the PLCε core.

Pyruvate kinase muscle isoform 2 (PKM2) is a key glycolytic enzyme and transcriptional coactivator and is critical for tumor metabolism. In cancer cells, native tetrameric PKM2 is phosphorylated or acetylated, which initiates a switch to a dimeric/monomeric form that translocates into the nucleus, causing oncogene transcription. However, it is not known how these post-translational modifications (PTMs) disrupt the oligomeric state of PKM2. We explored this question via crystallographic and biophysical analyses of PKM2 mutants containing residues that mimic phosphorylation and acetylation. We find that the PTMs elicit major structural reorganization of the fructose 1,6-bisphosphate (FBP), an allosteric activator, binding site, impacting the interaction with FBP and causing a disruption in oligomerization. To gain insight into how these modifications might cause unique outcomes in cancer cells, we examined the impact of increasing the intracellular pH (pHi) from ∼7.1 (in normal cells) to ∼7.5 (in cancer cells). Biochemical studies of WT PKM2 (wtPKM2) and the two mimetic variants demonstrated that the activity decreases as the pH is increased from 7.0 to 8.0, and wtPKM2 is optimally active and amenable to FBP-mediated allosteric regulation at pHi 7.5. However, the PTM mimetics exist as a mixture of tetramer and dimer, indicating that physiologically dimeric fraction is important and might be necessary for the modified PKM2 to translocate into the nucleus. Thus, our findings provide insight into how PTMs and pH regulate PKM2 and offer a broader understanding of its intricate allosteric regulation mechanism by phosphorylation or acetylation.

Defining discontinuous antigenic epitopes remains a substantial challenge, as exemplified by the case of lipid transfer polyproteins, which are common pollen allergens. Hydrogen/deuterium exchange monitored by NMR can be used to map epitopes onto folded protein surfaces, but only if the complex rapidly dissociates. Modifying the standard NMR-exchange measurement to detect substoichiometric complexes overcomes this time scale limitation and provides new insights into recognition of lipid transfer polyprotein by antibodies. In the future, this new and exciting development should see broad application to a range of tight macromolecular interactions.

E. A. Rakhmanov and S. P. Suetin
Trans. Moscow Math. Soc. 83 (), 269-290.
Abstract, references and article information

L. Oeding
Trans. Moscow Math. Soc. 83 (), 227-250.
Abstract, references and article information

Selim Esedoḡlu, Jiajia Guo and David Li
Math. Comp. 93 (), 2679-2710.
Abstract, references and article information

Kazuhiro Ishige, Paolo Salani and Asuka Takatsu
Trans. Amer. Math. Soc. 377 (), 5705-5748.
Abstract, references and article information

The Moog Image Dump posted a photo:

Bandai Namco 2024

dannyhennesy posted a photo:

On the Capital planet the rebellious droids had followed maily the Bat-Bot, but as time progressed his circuits had gone all mushy at 780 years or so without maintenance…

Several splinter groups all with their local bot leaders emerged such as the Che-bot, the traffic-light-robot and the Butt-bot, but none of these collected enough sentient circuits to call themselves a popular (or Animata) mass movement!

That was until a cyborg came along, one known as Jones, a long time prisoner and terrorist, his easy solutions to every problem rang well in the masses' auditory circuits!!!

His slogans and simple rhetoric were simple enough for the simple traffic-light to comprehend and cheer!

His language was full of hate towards the organics and especially the humans who were the most common races among the ruling class of the federation!!!

Despite being a “Fleshie” himself his message collected the angry enslaved
bot community by only weeks all rebellious robots except for a few fringe loonies had forgotten the old leaders…

One morning at Jones gave the signal…

All over the capital planet hordes and swarms of any form of mechanical sentient beings attacked first the police stations, then the Company boards running the planet and the federation as well as their starfleet…

Many died, especially the low level police and army! Many mechanicals died too, but their ranks were soon filled by Mutant fleshie allies of the lower levels who hated the Federation feudal society and upper classes as much as their technological allies…

The Federation state apparatus and ruling class, most of their fleet army fled when they knew the game was up, they activated the emergency escape plan and whole city blocks with important factories, administrational units, valuable assets and so on separated from the capital by hidden rocket engines and homed in their course to Mars…

On Mars the federation regrouped and formed their new society…

On the Capital planet, the robots proclaimed the first Techno-republic of the advanced inorganic civilization, the low level fleshies left behind, became slaves and their mutant allies got to rule their own minute chiefdoms as protectorates under the Techno-republic…

Jones was now the undisputed ruler of the capital planet, but the victory was a pyrros one since, all important buildings, all of value was now one Mars!

But as Jones put it:

Our proud race the Techno-species didn’t need the Fleshies administration, their infrastructure, their spaceships…

We shall start from scratch, with a new administration, a new order, every droid shall work at 4x speed than they did during human oppression since now we are free and the fleshies shall work twice as hard than the Techno-Race, until we have breed enough new fleshies so they can do all work!

Our future is bright and shiny like glistering shiny metal!

The snapshot seen here is from the first police station attacked in sector 45-34v-ss-g the first one to fall according to official techno-history!

———————————————/
Designers note:

I am sad to say that this is the last episode in this years-spanning space series… At least for a while, I will still post LEGO hobby stuff here but without a storyline, perhaps small designs and builds… and occasionally a story when I feel like it!!!

I would like to thank all who had been in this journey of our heros, but it has taken far to much time and effort and since the state of the world is as it is, I am spiraling down in another depression, I must stop it before I reach the abyss, so I have remove some stress out of my equation… I ended it in a cliffhanger so I can easily restart it when my mental health improves… I hope that won’t be forever???

I would love if someone used my characters or ideas, please send me a link if you do, I would love to read it or look at it!!!

But there will be more Lego, just in different format without long stories, I need to focus more on my art and to be honest that is the only time the mental pain eases, when I create!!!


Peace and Noise!

MushroomBrain a FOL

Photo- Roy posted a photo:

Olha Prykhodko and Kostiantyn Ralchenko
Theor. Probability and Math. Statist. 111 (), 123-135.
Abstract, references and article information

Paweł Hitczenko and Nick Wormald
Proc. Amer. Math. Soc. 152 (), 5411-5427.
Abstract, references and article information

If you connect to a FTP/TLS server that is configured to use implicit FTP/TLS, FILENAME FTP/TLS might fail with the following error:

Recent studies have suggested that innate immune responses exhibit characteristics associated with memory linked to modulations in both vertebrates and invertebrates. However, the diverse evolutionary paths taken, particularly within the invertebrate taxa, should lead to similarly diverse innate immunity memory processes. Our understanding of innate immune memory in invertebrates primarily comes from studies of the fruit fly Drosophila melanogaster, the generality of which is unclear. Caenorhabditis elegans typically inhabits soil harboring a variety of fatal microbial pathogens; for this invertebrate, the innate immune system and aversive behavior are the major defensive strategies against microbial infection. However, their characteristics of immunological memory remains infantile. Here we discovered an immunological memory that promoted avoidance and suppressed innate immunity during reinfection with bacteria, which we revealed to be specific to the previously exposed pathogens. During this trade-off switch of avoidance and innate immunity, the chemosensory neurons AWB and ADF modulated production of serotonin and dopamine, which in turn decreased expression of the innate immunity-associated genes and led to enhanced avoidance via the downstream insulin-like pathway. Therefore, our current study profiles the immune memories during C. elegans reinfected by pathogenic bacteria and further reveals that the chemosensory neurons, the neurotransmitter(s), and their associated molecular signaling pathways are responsible for a trade-off switch between the two immunological memories.

Animals can sense the presence of microbes in their tissues and mobilize their own defenses by recognizing and responding to conserved microbial structures (often called microbe-associated molecular patterns (MAMPs)). Successful host defenses may kill the invaders, yet the host animal may fail to restore homeostasis if the stimulatory microbial structures are not silenced. Although mice have many mechanisms for limiting their responses to lipopolysaccharide (LPS), a major Gram-negative bacterial MAMP, a highly conserved host lipase is required to extinguish LPS sensing in tissues and restore homeostasis. We review recent progress in understanding how this enzyme, acyloxyacyl hydrolase (AOAH), transforms LPS from stimulus to inhibitor, reduces tissue injury and death from infection, prevents prolonged post-infection immunosuppression, and keeps stimulatory LPS from entering the bloodstream. We also discuss how AOAH may increase sensitivity to pulmonary allergens. Better appreciation of how host enzymes modify LPS and other MAMPs may help prevent tissue injury and hasten recovery from infection.

Knockout mouse models have been extensively used to study the antiviral activity of IFIT (interferon-induced protein with tetratricopeptide repeats). Human IFIT1 binds to cap0 (m7GpppN) RNA, which lacks methylation on the first and second cap-proximal nucleotides (cap1, m7GpppNm, and cap2, m7GpppNmNm, respectively). These modifications are signatures of “self” in higher eukaryotes, whereas unmodified cap0-RNA is recognized as foreign and, therefore, potentially harmful to the host cell. IFIT1 inhibits translation at the initiation stage by competing with the cap-binding initiation factor complex, eIF4F, restricting infection by certain viruses that possess “nonself” cap0-mRNAs. However, in mice and other rodents, the IFIT1 orthologue has been lost, and the closely related Ifit1b has been duplicated twice, yielding three paralogues: Ifit1, Ifit1b, and Ifit1c. Although murine Ifit1 is similar to human IFIT1 in its cap0-RNA–binding selectivity, the roles of Ifit1b and Ifit1c are unknown. Here, we found that Ifit1b preferentially binds to cap1-RNA, whereas binding is much weaker to cap0- and cap2-RNA. In murine cells, we show that Ifit1b can modulate host translation and restrict WT mouse coronavirus infection. We found that Ifit1c acts as a stimulatory cofactor for both Ifit1 and Ifit1b, promoting their translation inhibition. In this way, Ifit1c acts in an analogous fashion to human IFIT3, which is a cofactor to human IFIT1. This work clarifies similarities and differences between the human and murine IFIT families to facilitate better design and interpretation of mouse models of human infection and sheds light on the evolutionary plasticity of the IFIT family.

Myelination plays an important role in cognitive development and in demyelinating diseases like multiple sclerosis (MS), where failure of remyelination promotes permanent neuro-axonal damage. Modification of cell surface receptors with branched N-glycans coordinates cell growth and differentiation by controlling glycoprotein clustering, signaling, and endocytosis. GlcNAc is a rate-limiting metabolite for N-glycan branching. Here we report that GlcNAc and N-glycan branching trigger oligodendrogenesis from precursor cells by inhibiting platelet-derived growth factor receptor-α cell endocytosis. Supplying oral GlcNAc to lactating mice drives primary myelination in newborn pups via secretion in breast milk, whereas genetically blocking N-glycan branching markedly inhibits primary myelination. In adult mice with toxin (cuprizone)-induced demyelination, oral GlcNAc prevents neuro-axonal damage by driving myelin repair. In MS patients, endogenous serum GlcNAc levels inversely correlated with imaging measures of demyelination and microstructural damage. Our data identify N-glycan branching and GlcNAc as critical regulators of primary myelination and myelin repair and suggest that oral GlcNAc may be neuroprotective in demyelinating diseases like MS.

Connexin (Cx) protein forms hemichannels and gap junctional channels, which play diverse and profound roles in human physiology and diseases. Gap junctions are arrays of intercellular channels formed by the docking of two hemichannels from adjacent cells. Each hexameric hemichannel contains the same or different Cx isoform. Although homomeric Cxs forms have been largely described functionally and structurally, the stoichiometry and arrangement of heteromeric Cx channels remain unknown. The latter, however, are widely expressed in human tissues and variation might have important implications on channel function. Investigating properties of heteromeric Cx channels is challenging considering the high number of potential subunit arrangements and stoichiometries, even when only combining two Cx isoforms. To tackle this problem, we engineered an HA tag onto Cx26 or Cx30 subunits and imaged hemichannels that were liganded by Fab-epitope antibody fragments via atomic force microscopy. For Cx26-HA/Cx30 or Cx30-HA/Cx26 heteromeric channels, the Fab-HA binding distribution was binomial with a maximum of three Fab-HA bound. Furthermore, imaged Cx26/Cx30-HA triple liganded by Fab-HA showed multiple arrangements that can be derived from the law of total probabilities. Atomic force microscopy imaging of ringlike structures of Cx26/Cx30-HA hemichannels confirmed these findings and also detected a polydisperse distribution of stoichiometries. Our results indicate a dominant subunit stoichiometry of 3Cx26:3Cx30 with the most abundant subunit arrangement of Cx26-Cx26-Cx30-Cx26-Cx30-Cx30. To our knowledge, this is the first time that the molecular architecture of heteromeric Cx channels has been revealed, thus providing the basis to explore the functional effect of these channels in biology.

Heme oxygenase-2 (HO2) and -1 (HO1) catalyze heme degradation to biliverdin, CO, and iron, forming an essential link in the heme metabolism network. Tight regulation of the cellular levels and catalytic activities of HO1 and HO2 is important for maintaining heme homeostasis. HO1 expression is transcriptionally regulated; however, HO2 expression is constitutive. How the cellular levels and activity of HO2 are regulated remains unclear. Here, we elucidate the mechanism of post-translational regulation of cellular HO2 levels by heme. We find that, under heme-deficient conditions, HO2 is destabilized and targeted for degradation, suggesting that heme plays a direct role in HO2 regulation. HO2 has three heme binding sites: one at its catalytic site and the others at its two heme regulatory motifs (HRMs). We report that, in contrast to other HRM-containing proteins, the cellular protein level and degradation rate of HO2 are independent of heme binding to the HRMs. Rather, under heme deficiency, loss of heme binding to the catalytic site destabilizes HO2. Consistently, an HO2 catalytic site variant that is unable to bind heme exhibits a constant low protein level and an enhanced protein degradation rate compared with the WT HO2. Finally, HO2 is degraded by the lysosome through chaperone-mediated autophagy, distinct from other HRM-containing proteins and HO1, which are degraded by the proteasome. These results reveal a novel aspect of HO2 regulation and deepen our understanding of HO2's role in maintaining heme homeostasis, paving the way for future investigation into HO2's pathophysiological role in heme deficiency response.

The bacterial enhancer-binding protein (bEBP) FlrC, controls motility and colonization of Vibrio cholerae by regulating the transcription of class-III flagellar genes in σ54-dependent manner. However, the mechanism by which FlrC regulates transcription is not fully elucidated. Although, most bEBPs require nucleotides to stimulate the oligomerization necessary for function, our previous study showed that the central domain of FlrC (FlrCC) forms heptamer in a nucleotide-independent manner. Furthermore, heptameric FlrCC binds ATP in “cis-mediated” style without any contribution from sensor I motif 285REDXXYR291 of the trans protomer. This atypical ATP binding raises the question of whether heptamerization of FlrC is solely required for transcription regulation, or if it is also critical for ATPase activity. ATPase assays and size exclusion chromatography of the trans-variants FlrCC-Y290A and FlrCC-R291A showed destabilization of heptameric assembly with concomitant abrogation of ATPase activity. Crystal structures showed that in the cis-variant FlrCC-R349A drastic shift of Walker A encroached ATP-binding site, whereas the site remained occupied by ADP in FlrCC-Y290A. We postulated that FlrCC heptamerizes through concentration-dependent cooperativity for maximal ATPase activity and upon heptamerization, packing of trans-acting Tyr290 against cis-acting Arg349 compels Arg349 to maintain proper conformation of Walker A. Finally, a Trp quenching study revealed binding of cyclic-di-GMP with FlrCC. Excess cyclic-di-GMP repressed ATPase activity of FlrCC through destabilization of heptameric assembly, especially at low concentration of protein. Systematic phylogenetic analysis allowed us to propose similar regulatory mechanisms for FlrCs of several Vibrio species and a set of monotrichous Gram-negative bacteria.

CD81 plays a central role in a variety of physiological and pathological processes. Recent structural analysis of CD81 indicates that it contains an intramembrane cholesterol-binding pocket and that interaction with cholesterol may regulate a conformational switch in the large extracellular domain of CD81. Therefore, CD81 possesses a potential cholesterol-sensing mechanism; however, its relevance for protein function is thus far unknown. In this study we investigate CD81 cholesterol sensing in the context of its activity as a receptor for hepatitis C virus (HCV). Structure-led mutagenesis of the cholesterol-binding pocket reduced CD81–cholesterol association but had disparate effects on HCV entry, both reducing and enhancing CD81 receptor activity. We reasoned that this could be explained by alterations in the consequences of cholesterol binding. To investigate this further we performed molecular dynamic simulations of CD81 with and without cholesterol; this identified a potential allosteric mechanism by which cholesterol binding regulates the conformation of CD81. To test this, we designed further mutations to force CD81 into either the open (cholesterol-unbound) or closed (cholesterol-bound) conformation. The open mutant of CD81 exhibited reduced HCV receptor activity, whereas the closed mutant enhanced activity. These data are consistent with cholesterol sensing switching CD81 between a receptor active and inactive state. CD81 interactome analysis also suggests that conformational switching may modulate the assembly of CD81–partner protein networks. This work furthers our understanding of the molecular mechanism of CD81 cholesterol sensing, how this relates to HCV entry, and CD81's function as a molecular scaffold; these insights are relevant to CD81's varied roles in both health and disease.

Bacterial low-copy-number plasmids require partition (par) systems to ensure their stable inheritance by daughter cells. In general, these systems consist of three components: a centromeric DNA sequence, a centromere-binding protein and a nucleotide hydrolase that polymerizes and functions as a motor. Type III systems, however, segregate plasmids using three proteins: the FtsZ/tubulin-like GTPase TubZ, the centromere-binding protein TubR and the MerR-like transcriptional regulator TubY. Although the TubZ filament is sufficient to transport the TubR-centromere complex in vitro, TubY is still necessary for the stable maintenance of the plasmid. TubY contains an N-terminal DNA-binding helix-turn-helix motif and a C-terminal coiled-coil followed by a cluster of lysine residues. This study determined the crystal structure of the C-terminal domain of TubY from the Bacillus cereus pXO1-like plasmid and showed that it forms a tetrameric parallel four-helix bundle that differs from the typical MerR family proteins with a dimeric anti-parallel coiled-coil. Biochemical analyses revealed that the C-terminal tail with the conserved lysine cluster helps TubY to stably associate with the TubR-centromere complex as well as to nonspecifically bind DNA. Furthermore, this C-terminal tail forms an amphipathic helix in the presence of lipids but must oligomerize to localize the protein to the membrane in vivo. Taken together, these data suggest that TubY is a component of the nucleoprotein complex within the partitioning machinery, and that lipid membranes act as mediators of type III systems.

Members of the B-cell lymphoma (BCL-2) protein family regulate mitochondrial outer membrane permeabilization (MOMP), a phenomenon in which mitochondria become porous and release death-propagating complexes during the early stages of apoptosis. Pro-apoptotic BCL-2 proteins oligomerize at the mitochondrial outer membrane during MOMP, inducing pore formation. Of current interest are endogenous factors that can inhibit pro-apoptotic BCL-2 mitochondrial outer membrane translocation and oligomerization. A mitochondrial-derived peptide, Humanin (HN), was reported being expressed from an alternate ORF in the mitochondrial genome and inhibiting apoptosis through interactions with the pro-apoptotic BCL-2 proteins. Specifically, it is known to complex with BAX and BID. We recently reported the fibrillation of HN and BAX into β-sheets. Here, we detail the fibrillation between HN and BID. These fibers were characterized using several spectroscopic techniques, protease fragmentation with mass analysis, and EM. Enhanced fibrillation rates were detected with rising temperatures or pH values and the presence of a detergent. BID fibers are similar to those produced using BAX; however, the structures differ in final conformations of the BCL-2 proteins. BID fibers display both types of secondary structure in the fiber, whereas BAX was converted entirely to β-sheets. The data show that two distinct segments of BID are incorporated into the fiber structure, whereas other portions of BID remain solvent-exposed and retain helical structure. Similar analyses show that anti-apoptotic BCL-xL does not form fibers with humanin. These results support a general mechanism of sequestration of pro-apoptotic BCL-2 proteins into fibers by HN to inhibit MOMP.

20 August 2020

Cellular energy demands are met by uptake and metabolism of nutrients like glucose. The principal transcriptional regulator for adapting glycolytic flux and downstream pathways like de novo lipogenesis to glucose availability in many cell types is carbohydrate response element–binding protein (ChREBP). ChREBP is activated by glucose metabolites and post-translational modifications, inducing nuclear accumulation and regulation of target genes. Here we report that ChREBP is modified by proline hydroxylation at several residues. Proline hydroxylation targets both ectopically expressed ChREBP in cells and endogenous ChREBP in mouse liver. Functionally, we found that specific hydroxylated prolines were dispensable for protein stability but required for the adequate activation of ChREBP upon exposure to high glucose. Accordingly, ChREBP target gene expression was rescued by re-expressing WT but not ChREBP that lacks hydroxylated prolines in ChREBP-deleted hepatocytes. Thus, proline hydroxylation of ChREBP is a novel post-translational modification that may allow for therapeutic interference in metabolic diseases.

Environmental factors, such as viral infection, are proposed to play a role in the initiation of autoimmune diabetes. In response to encephalomyocarditis virus (EMCV) infection, resident islet macrophages release the pro-inflammatory cytokine IL-1β, to levels that are sufficient to stimulate inducible nitric oxide synthase (iNOS) expression and production of micromolar levels of the free radical nitric oxide in neighboring β-cells. We have recently shown that nitric oxide inhibits EMCV replication and EMCV-mediated β-cell lysis and that this protection is associated with an inhibition of mitochondrial oxidative metabolism. Here we show that the protective actions of nitric oxide against EMCV infection are selective for β-cells and associated with the metabolic coupling of glycolysis and mitochondrial oxidation that is necessary for insulin secretion. Inhibitors of mitochondrial respiration attenuate EMCV replication in β-cells, and this inhibition is associated with a decrease in ATP levels. In mouse embryonic fibroblasts (MEFs), inhibition of mitochondrial metabolism does not modify EMCV replication or decrease ATP levels. Like most cell types, MEFs have the capacity to uncouple the glycolytic utilization of glucose from mitochondrial respiration, allowing for the maintenance of ATP levels under conditions of impaired mitochondrial respiration. It is only when MEFs are forced to use mitochondrial oxidative metabolism for ATP generation that mitochondrial inhibitors attenuate viral replication. In a β-cell selective manner, these findings indicate that nitric oxide targets the same metabolic pathways necessary for glucose stimulated insulin secretion for protection from viral lysis.

Silencing the Guns in Africa by 2030: Lessons from Mozambique 17 February 2023 — 7:00AM TO 9:00AM Anonymous (not verified) 7 February 2023 Addis Ababa and online

A hybrid event in Addis Ababa reflecting on Mozambique’s 2019 peace agreement and the lessons it offers for the African Union’s ‘Silencing the Guns’ agenda by 2030.

This event will explore opportunities for furthering the AU’s Silencing the Guns agenda by 2030 to assist Africa’s transformative development, highlighting lessons learnt from Mozambique’s experience.

The ‘Silencing the Guns in Africa’ agenda, a flagship initiative of the African Union’s (AU) Agenda 2063, aspires to end all wars and conflict, prevent genocide, and stop gender-based violence.

The 2019 peace agreement in Mozambique and the subsequent disarmament, demobilization and reintegration process supported by the United Nations (UN) but implemented by Mozambique’s government and institutions, provides experience and learning for other continental conflicts that have recently ended or resumed.

Mozambique is seeking to break from the cyclical ‘conflict trap’ where once a country experiences one civil war, it is significantly more likely to experience additional episodes of violence.

Since the end of Mozambique’s civil war in 1992, targeted armed conflict by RENAMO resumed in 2013 and ended through the new agreement in August 2019. The final reintegration into civilian life of former Mozambican combatants of opposition RENAMO will be completed in 2023.

Mozambique and Switzerland – a key supporter of successive Mozambican peace processes – have become non-permanent members of the UN Security Council for the first time in their respective histories.

At a moment when old vulnerabilities and new threats are apparent on the African continent, this seminar, held by Chatham House in partnership with the United Nations Development Programme (UNDP), explores opportunities to furthering the AU’s Silencing the Guns agenda by 2030 to assist Africa’s transformative development, as outlined by the UNDP in a report published in February 2022.

This hybrid event is held in partnership with the African Union Commission and the United Nations Development Programme (UNDP).

This event will also be broadcast live via the Africa Programme Facebook page.

Visual Abstract

Visual Abstract

Simone Kurz
Dec 29, 2020; 0:RA120.002266v1-mcp.RA120.002266
Research