George H. Rothblat
May 1, 1999; 40:781-796
Reviews

Cheng Chu
Proc. Amer. Math. Soc. 152 (), 5289-5297.
Abstract, references and article information

Simão Correia
Proc. Amer. Math. Soc. 152 (), 5117-5136.
Abstract, references and article information

α-Linked galactose is a common carbohydrate motif in nature that is processed by a variety of glycoside hydrolases from different families. Terminal Galα1–3Gal motifs are found as a defining feature of different blood group and tissue antigens, as well as the building block of the marine algal galactan λ-carrageenan. The blood group B antigen and linear α-Gal epitope can be processed by glycoside hydrolases in family GH110, whereas the presence of genes encoding GH110 enzymes in polysaccharide utilization loci from marine bacteria suggests a role in processing λ-carrageenan. However, the structure–function relationships underpinning the α-1,3-galactosidase activity within family GH110 remain unknown. Here we focus on a GH110 enzyme (PdGH110B) from the carrageenolytic marine bacterium Pseudoalteromonas distincta U2A. We showed that the enzyme was active on Galα1–3Gal but not the blood group B antigen. X-ray crystal structures in complex with galactose and unhydrolyzed Galα1–3Gal revealed the parallel β-helix fold of the enzyme and the structural basis of its inverting catalytic mechanism. Moreover, an examination of the active site reveals likely adaptations that allow accommodation of fucose in blood group B active GH110 enzymes or, in the case of PdGH110, accommodation of the sulfate groups found on λ-carrageenan. Overall, this work provides insight into the first member of a predominantly marine clade of GH110 enzymes while also illuminating the structural basis of α-1,3-galactoside processing by the family as a whole.

26 August 2020

Visual Abstract

Kinases are critical components of intracellular signaling pathways and have been extensively investigated with regard to their roles in cancer. p21-activated kinase-1 (PAK1) is a serine/threonine kinase that has been previously implicated in numerous biological processes, such as cell migration, cell cycle progression, cell motility, invasion, and angiogenesis, in glioma and other cancers. However, the signaling network linked to PAK1 is not fully defined. We previously reported a large-scale yeast genetic interaction screen using toxicity as a readout to identify candidate PAK1 genetic interactions. En masse transformation of the PAK1 gene into 4,653 homozygous diploid Saccharomyces cerevisiae yeast deletion mutants identified ∼400 candidates that suppressed yeast toxicity. Here we selected 19 candidate PAK1 genetic interactions that had human orthologs and were expressed in glioma for further examination in mammalian cells, brain slice cultures, and orthotopic glioma models. RNAi and pharmacological inhibition of potential PAK1 interactors confirmed that DPP4, KIF11, mTOR, PKM2, SGPP1, TTK, and YWHAE regulate PAK1-induced cell migration and revealed the importance of genes related to the mitotic spindle, proteolysis, autophagy, and metabolism in PAK1-mediated glioma cell migration, drug resistance, and proliferation. AKT1 was further identified as a downstream mediator of the PAK1-TTK genetic interaction. Taken together, these data provide a global view of PAK1-mediated signal transduction pathways and point to potential new drug targets for glioma therapy.

Genetic mutations related to ALS, a progressive neurological disease, have been discovered in the gene encoding σ-1 receptor (σ1R). We previously reported that σ1RE102Q elicits toxicity in cells. The σ1R forms oligomeric states that are regulated by ligands. Nevertheless, little is known about the effect of ALS-related mutations on oligomer formation. Here, we transfected NSC-34 cells, a motor neuronal cell line, and HEK293T cells with σ1R-mCherry (mCh), σ1RE102Q-mCh, or nontagged forms to investigate detergent solubility and subcellular distribution using immunocytochemistry and fluorescence recovery after photobleaching. The oligomeric state was determined using crosslinking procedure. σ1Rs were soluble to detergents, whereas the mutants accumulated in the insoluble fraction. Within the soluble fraction, peak distribution of mutants appeared in higher sucrose density fractions. Mutants formed intracellular aggregates that were co-stained with p62, ubiquitin, and phosphorylated pancreatic eukaryotic translation initiation factor-2-α kinase in NSC-34 cells but not in HEK293T cells. The aggregates had significantly lower recovery in fluorescence recovery after photobleaching. Acute treatment with σ1R agonist SA4503 failed to improve recovery, whereas prolonged treatment for 48 h significantly decreased σ1RE102Q-mCh insolubility and inhibited apoptosis. Whereas σ1R-mCh formed monomers and dimers, σ1RE102Q-mCh also formed trimers and tetramers. SA4503 reduced accumulation of the four types in the insoluble fraction and increased monomers in the soluble fraction. The σ1RE102Q insolubility was diminished by σ1R-mCh co-expression. These results suggest that the agonist and WT σ1R modify the detergent insolubility, toxicity, and oligomeric state of σ1RE102Q, which may lead to promising new treatments for σ1R-related ALS.

Mutations in the GUCY2D gene coding for the dimeric human retinal membrane guanylyl cyclase (RetGC) isozyme RetGC1 cause various forms of blindness, ranging from rod dysfunction to rod and cone degeneration. We tested how the mutations causing recessive congenital stationary night blindness (CSNB), recessive Leber's congenital amaurosis (LCA1), and dominant cone–rod dystrophy-6 (CORD6) affected RetGC1 activity and regulation by RetGC-activating proteins (GCAPs) and retinal degeneration-3 protein (RD3). CSNB mutations R666W, R761W, and L911F, as well as LCA1 mutations R768W and G982VfsX39, disabled RetGC1 activation by human GCAP1, -2, and -3. The R666W and R761W substitutions compromised binding of GCAP1 with RetGC1 in HEK293 cells. In contrast, G982VfsX39 and L911F RetGC1 retained the ability to bind GCAP1 in cyto but failed to effectively bind RD3. R768W RetGC1 did not bind either GCAP1 or RD3. The co-expression of GUCY2D allelic combinations linked to CSNB did not restore RetGC1 activity in vitro. The CORD6 mutation R838S in the RetGC1 dimerization domain strongly dominated the Ca2+ sensitivity of cyclase regulation by GCAP1 in RetGC1 heterodimer produced by co-expression of WT and the R838S subunits. It required higher Ca2+ concentrations to decelerate GCAP-activated RetGC1 heterodimer—6-fold higher than WT and 2-fold higher than the Ser838-harboring homodimer. The heterodimer was also more resistant than homodimers to inhibition by RD3. The observed biochemical changes can explain the dominant CORD6 blindness and recessive LCA1 blindness, both of which affect rods and cones, but they cannot explain the selective loss of rod function in recessive CSNB.

As the capability of mass spectrometry-based proteomics has matured, tens of thousands of peptides can be measured simultaneously, which has the benefit of offering a systems view of protein expression. However, a major challenge is that with an increase in throughput, protein quantification estimation from the native measured peptides has become a computational task. A limitation to existing computationally-driven protein quantification methods is that most ignore protein variation, such as alternate splicing of the RNA transcript and post-translational modifications or other possible proteoforms, which will affect a significant fraction of the proteome. The consequence of this assumption is that statistical inference at the protein level, and consequently downstream analyses, such as network and pathway modeling, have only limited power for biomarker discovery. Here, we describe a Bayesian model (BP-Quant) that uses statistically derived peptides signatures to identify peptides that are outside the dominant pattern, or the existence of multiple over-expressed patterns to improve relative protein abundance estimates. It is a research-driven approach that utilizes the objectives of the experiment, defined in the context of a standard statistical hypothesis, to identify a set of peptides exhibiting similar statistical behavior relating to a protein. This approach infers that changes in relative protein abundance can be used as a surrogate for changes in function, without necessarily taking into account the effect of differential post-translational modifications, processing, or splicing in altering protein function. We verify the approach using a dilution study from mouse plasma samples and demonstrate that BP-Quant achieves similar accuracy as the current state-of-the-art methods at proteoform identification with significantly better specificity. BP-Quant is available as a MatLab ® and R packages at https://github.com/PNNL-Comp-Mass-Spec/BP-Quant.

Infrastructure Management Contracts: Improving Energy Asset Management in Displacement Settings Research paper sysadmin 17 April 2019

This paper highlights a number of options for managing electricity infrastructure in refugee camps and outlines the challenges, opportunities and operational implications associated with them. It takes the Kalobeyei settlement in Kenya as a case study.

• Building and maintaining electricity infrastructure to power offices, businesses, households and other operations in displacement settings is difficult. It is especially challenging for the Office of the United Nations High Commissioner for Refugees (UNHCR) and its partner agencies, because supplying electricity is not their core business.
• Private-sector companies exist that are willing and able to develop infrastructure management contracts to provide energy as a service in displacement settings. However, institutional barriers within humanitarian agencies persist, with short budgeting cycles in particular preventing humanitarian agencies from entering into the sorts of long-term service agreements required by the private sector.
• A number of options exist to leverage the expertise of the private sector through ‘public–private partnership’ (P3) structures. Such mechanisms can promote more efficient management of infrastructure by drawing on private-sector experience and expertise, incentivizing appropriate risk-sharing and providing options to leverage private capital in project development.
• Field work from the Kalobeyei settlement in Kenya suggests that a solar/diesel hybrid mini-grid solution was the most economical option to power camp services and infrastructure there. Compared to distributed diesel generation, the annual savings in operating costs were estimated at $49,880, with the additional investment paid back within 3.6 years.
• Humanitarian agencies need to be willing to change their policies to enable long-term service agreements. Alternatively (or, more likely, in conjunction with this option), financial mechanisms such as partial risk guarantees need to be developed to offset some of the risks. This change will need high-level support from donors and humanitarian agencies.
• Once the first infrastructure management contracts can be signed and tested in displacement locations (through the use of donor funding or otherwise) and associated data collected, it will ease the way for future investments in these types of projects.

Leading up to the start of Spring Training, the Around the Horn series will examine each of the Angels' positional groupings heading into the 2019 season. Here's a look at the bullpen.

Improving Economic Management for Sustainable Growth in Zambia 13 July 2018 — 9:00AM TO 10:00AM Anonymous (not verified) 19 June 2018 Chatham House, London

THIS EVENT IS POSTPONED.

High levels of infrastructure investment funded by commercial loans, against a backdrop of subdued economic growth, resulted in an increase in Zambia’s public external debt from $8.7 billion in 2017 to $9.3 billion in March 2018.

In June 2018 Zambia’s Ministry of Finance announced new austerity measures aimed at reducing the country’s debt burden, as part of an ongoing reform agenda that is hoped to stabilise the economy.

In the meantime Zambia grapples with severe social and development challenges. Decreased spending in health, education and social protection, and poor access in rural areas, have already left Zambia ranked 139th out of 188 countries in the UNDP’s 2016 human development index.

At this meeting Margaret Mwanakatwe, minister of finance, discusses the government’s financial reform agenda, its engagement with creditors and IFIs, and plans for generating sustainable growth and job creation.

Eurovision, war and the geopolitics of pop The World Today mhiggins.drupal 28 March 2023

Europe’s great song competition may strive for continental harmony, but bitter conflicts and voting blocs often drag it off key, writes Saskia Postema.

In May, the city that spawned the Beatles will add another notch to its cultural belt as Liverpool hosts the Eurovision Song Contest.

The pop competition has been celebrating extravagance, dramatic acts and lots of glitter since 1956. It is expressly designed to be non-political, with performers barred from promoting political interests, yet it exists for a specific political purpose – to promote European unity.

The organizer, the European Broadcasting Union (EBU), has certainly succeeded in part with its mission. While Europe Day on May 9 comes and goes without much fanfare, Eurovision is an eagerly anticipated fixture on the cultural calendar.

Cultural diplomacy

While some may dismiss it as simply an extravagant party, there is more to it than that: it is a form of cultural diplomacy. Beyond artistry, acts are expected to bring their cultural identity to the stage as they bid for douze points, Eurovision’s highest score, from national juries.

Like any popular forum, it reflects popular opinion. So, when war threatens the European harmony Eurovision is meant to exude, politics inevitably manifests itself.

This was evident last year. Following Russia’s invasion of Ukraine in February, Eurovision’s organizers reiterated their apolitical stance stating both countries would be allowed to participate. But when various countries threatened to withdraw if Russia was allowed to compete, the EBU changed its tune and broke off ties with Russian broadcasting agencies indefinitely. As reluctant as it was to act in this capacity, the organization still inadvertently highlighted its role as a political gatekeeper and confirmed Eurovision does function as a political arena.

Unsurprisingly, all eyes were on the Ukrainian entry that year. Kalush Orchestra’s Stefania, presenting a blend of traditional Ukrainian folk music with hip hop beats, went on to win the contest resoundingly.

And while the winning nation normally hosts next year’s competition, due to the war this honour passed to the runner-up, the United Kingdom. Britain, coincidentally, has been one of the most visible supporters of Kyiv’s war efforts. Boris Johnson, the former prime minister, was among the first leaders to visit Kyiv after the Russian invasion.

Last year’s second place ended a long spate of poor results for the UK in the competition. The first year it scored nul points was 2003 when the UK entry was Cry Baby by the duo Jemini. The result was seen widely as a backlash against Britain’s entry into the Iraq war earlier that year.

In the intervening years it has been placed last twice and received nul points again in 2021 when the entry was Embers sung by James Newman. With last year’s second place for Sam Ryder’s Space Man, the UK redeemed itself and will get to host Eurovision in Liverpool, a city twinned with Odesa since 1957.

It is not the first time that Russia’s geopolitical relations have led to Eurovision controversy. In 2008, following the Russo-Georgian war, Russia recognized the self-proclaimed independence of South Ossetia and Abkhazia which had broken away from Georgia.

As a result, Georgia initially refused to take part in the 2009 Eurovision as it was to be held in Moscow. It changed its mind, however, submitting a song by Stefane and 3G called We Don’t Wanna Put In. The submission was rejected by the EBU, which said it contained obvious references to the Russian leader, something Georgia denied.

In 2015, Ukraine withdrew from Eurovision following the Russian annexation of Crimea. The following year the EBU was faced with a similar problem when Ukraine submitted a song, 1944,sung by Jamala, which told the story of her great-grandmother who lived through the mass deportation of Crimean Tatars in the Soviet Union under Josef Stalin. This time the EBU allowed the entry, despite the Russian Duma calling for its rejection. The song went on to win.