Cholera Toxin B Subunits Assemble into Pentamers - Proposition of a Fly-Casting Mechanism

The cholera toxin B pentamer (CtxB5), which belongs to the AB5 toxin family, is used as a model study for protein assembly. The effect of the pH on the reassembly of the toxin was investigated using immunochemical, electrophoretic and spectroscopic methods. Three pH-dependent steps were identified during the toxin reassembly: (i) acquisition of a fully assembly-competent fold by the CtxB monomer, (ii) association of CtxB monomer into oligomers, (iii) acquisition of the native fold by the CtxB pentamer. The results show that CtxB5 and the related heat labile enterotoxin LTB5 have distinct mechanisms of assembly despite sharing high sequence identity (84%) and almost identical atomic structures. The difference can be pinpointed to four histidines which are spread along the protein sequence and may act together. Thus, most of the toxin B amino acids appear negligible for the assembly, raising the possibility that assembly is driven by a small network of amino acids instead of involving all of them

Beta-Strand Interfaces of Non-Dimeric Protein Oligomers Are Characterized by Scattered Charged Residue Patterns

Protein oligomers are formed either permanently, transiently or even by default. The protein chains are associated through intermolecular interactions constituting the protein interface. The protein interfaces of 40 soluble protein oligomers of stœchiometries above two are investigated using a quantitative and qualitative methodology, which analyzes the x-ray structures of the protein oligomers and considers their interfaces as interaction networks. The protein oligomers of the dataset share the same geometry of interface, made by the association of two individual β-strands (β-interfaces), but are otherwise unrelated. The results show that the β-interfaces are made of two interdigitated interaction networks. One of them involves interactions between main chain atoms (backbone network) while the other involves interactions between side chain and backbone atoms or between only side chain atoms (side chain network). Each one has its own characteristics which can be associated to a distinct role. The secondary structure of the β-interfaces is implemented through the backbone networks which are enriched with the hydrophobic amino acids favored in intramolecular β-sheets (MCWIV). The intermolecular specificity is provided by the side chain networks via positioning different types of charged residues at the extremities (arginine) and in the middle (glutamic acid and histidine) of the interface. Such charge distribution helps discriminating between sequences of intermolecular β-strands, of intramolecular β-strands and of β-strands forming β-amyloid fibers. This might open new venues for drug designs and predictive tool developments. Moreover, the β-strands of the cholera toxin B subunit interface, when produced individually as synthetic peptides, are capable of inhibiting the assembly of the toxin into pentamers. Thus, their sequences contain the features necessary for a β-interface formation. Such β-strands could be considered as ‘assemblons’, independent associating units, by homology to the foldons (independent folding unit). Such property would be extremely valuable in term of assembly inhibitory drug development

Fundamental role of C1q in autoimmunity and inflammation

C1q, historically viewed as the initiating component of the classical complement pathway, also exhibits a variety of complement-independent activities in both innate and acquired immunity. Recent studies focusing on C1q\u27s suppressive role in the immune system have provided new insight into how abnormal C1q expression and bioactivity may contribute to autoimmunity. In particular, molecular networks involving C1q interactions with cell surface receptors and other ligands are emerging as mechanisms involved in C1q\u27s modulation of immunity. Here, we discuss the role of C1q in controlling immune cell function, including recently elucidated mechanisms of action, and suggest how these processes are critical for maintaining tissue homeostasis under steady-state conditions and in preventing autoimmunity

Evaluating the Impact of Nature-Based Solutions: A Handbook for Practitioners

The Handbook aims to provide decision-makers with a comprehensive NBS impact assessment framework, and a robust set of indicators and methodologies to assess impacts of nature-based solutions across 12 societal challenge areas: Climate Resilience; Water Management; Natural and Climate Hazards; Green Space Management; Biodiversity; Air Quality; Place Regeneration; Knowledge and Social Capacity Building for Sustainable Urban Transformation; Participatory Planning and Governance; Social Justice and Social Cohesion; Health and Well-being; New Economic Opportunities and Green Jobs. Indicators have been developed collaboratively by representatives of 17 individual EU-funded NBS projects and collaborating institutions such as the EEA and JRC, as part of the European Taskforce for NBS Impact Assessment, with the four-fold objective of: serving as a reference for relevant EU policies and activities; orient urban practitioners in developing robust impact evaluation frameworks for nature-based solutions at different scales; expand upon the pioneering work of the EKLIPSE framework by providing a comprehensive set of indicators and methodologies; and build the European evidence base regarding NBS impacts. They reflect the state of the art in current scientific research on impacts of nature-based solutions and valid and standardized methods of assessment, as well as the state of play in urban implementation of evaluation frameworks

Extensive innate immune gene activation accompanies brain aging, increasing vulnerability to cognitive decline and neurodegeneration: a microarray study

BACKGROUND: This study undertakes a systematic and comprehensive analysis of brain gene expression profiles of immune/inflammation-related genes in aging and Alzheimer’s disease (AD). METHODS: In a well-powered microarray study of young (20 to 59 years), aged (60 to 99 years), and AD (74 to 95 years) cases, gene responses were assessed in the hippocampus, entorhinal cortex, superior frontal gyrus, and post-central gyrus. RESULTS: Several novel concepts emerge. First, immune/inflammation-related genes showed major changes in gene expression over the course of cognitively normal aging, with the extent of gene response far greater in aging than in AD. Of the 759 immune-related probesets interrogated on the microarray, approximately 40% were significantly altered in the SFG, PCG and HC with increasing age, with the majority upregulated (64 to 86%). In contrast, far fewer immune/inflammation genes were significantly changed in the transition to AD (approximately 6% of immune-related probesets), with gene responses primarily restricted to the SFG and HC. Second, relatively few significant changes in immune/inflammation genes were detected in the EC either in aging or AD, although many genes in the EC showed similar trends in responses as in the other brain regions. Third, immune/inflammation genes undergo gender-specific patterns of response in aging and AD, with the most pronounced differences emerging in aging. Finally, there was widespread upregulation of genes reflecting activation of microglia and perivascular macrophages in the aging brain, coupled with a downregulation of select factors (TOLLIP, fractalkine) that when present curtail microglial/macrophage activation. Notably, essentially all pathways of the innate immune system were upregulated in aging, including numerous complement components, genes involved in toll-like receptor signaling and inflammasome signaling, as well as genes coding for immunoglobulin (Fc) receptors and human leukocyte antigens I and II. CONCLUSIONS: Unexpectedly, the extent of innate immune gene upregulation in AD was modest relative to the robust response apparent in the aged brain, consistent with the emerging idea of a critical involvement of inflammation in the earliest stages, perhaps even in the preclinical stage, of AD. Ultimately, our data suggest that an important strategy to maintain cognitive health and resilience involves reducing chronic innate immune activation that should be initiated in late midlife

Purification and functional reconstitution of the human CHIP28 water channel expressed in Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae was used for these proteins are of primary importance to appreciate heterologous expression of the human CHIP28 water their physiological role in living organisms. Aquaporin-1 channel (Aquaporin-1). A nine-amino- Recently, CHIP28 was expressed functionally in acid epitope of the influenza hemagglutinin protein yeast secretory vesicles in our laboratory (3). This work (HA epitope), recognized by the monoclonal antibody indicated that wild-type or mutant aquaporins could 12CA5, was chosen to tag CHIP28 at its N-terminus. be produced easily in this new heterologous expression Epitope-tagged CHIP28 was purified from yeast ex- system for functional analyses. Such studies are fretracts by immunochromatography on protein A/ quently limited in the other known expression systems, 12CA5-coupled beads, after KI extraction and deter- mainly due to maturation or sorting defects (4). It begent solubilization, then concentrated by anion ex- came possible to produce large amounts of aquaporins change chromatography. Purified protein was recon- from yeast cultures for biochemical and biophysical stituted in proteoliposomes and was shown to function studies. Here, we describe a simple method to purify as a water channel by stopped-flow spectrophotome- try. This study demonstrates that the yeast has the yeast-expressed CHIP28, after addition of an epitope capacity to produce functional aquaporins at levels tag at the protein N-terminus. The purification procesufficient for biochemical and biophysical analyses

Glycerol permeability of mutant aquaporin 1 and other AQP-MIP proteins: inhibition studies

Contains fulltext : 23958___.PDF (publisher's version ) (Open Access

Taking into account protective works in land-use planning for mountain torrential floods: state of the art of the present French practices

International audienceIn 1995, a law stated a common regulatory natural risk zoning for French municipalities through a land-use planning procedure called Risk Prevention Plan (PPR). In mountain valleys and especially within torrential watersheds, considering protective structures in those plans is an actual concern. Those protections do have an effect on phenomena and modify hazard and risk levels. This paper gives an overview on how torrential protective works are taken into account in present risk prevention plans. To carry out this study, 53 recent risk prevention plans over 11 French mountain departments were selected and analyzed through a common analysis grid. Torrential protection works are taken into account in more than one third of analyzed plans. Protections mostly considered are dikes, bank protections, check-dams and sediment traps. Modalities of integration of these structures vary from one plan to another, influencing both hazard and regulatory zoning. Results also show a wide range of practices between departments and even inside them. Conclusions brought out enhance knowledge about actual practices which were not sufficiently known so far. Findings and new additional recommendations will be included in a future PPR methodological guide exclusively suited for torrential context, which is currently still missing

Taking into account protective works in land-use planning for mountain torrential floods: state of the art of the present French practices

International audienceIn 1995, a law stated a common regulatory natural risk zoning for French municipalities through a land-use planning procedure called Risk Prevention Plan (PPR). In mountain valleys and especially within torrential watersheds, considering protective structures in those plans is an actual concern. Those protections do have an effect on phenomena and modify hazard and risk levels. This paper gives an overview on how torrential protective works are taken into account in present risk prevention plans. To carry out this study, 53 recent risk prevention plans over 11 French mountain departments were selected and analyzed through a common analysis grid. Torrential protection works are taken into account in more than one third of analyzed plans. Protections mostly considered are dikes, bank protections, check-dams and sediment traps. Modalities of integration of these structures vary from one plan to another, influencing both hazard and regulatory zoning. Results also show a wide range of practices between departments and even inside them. Conclusions brought out enhance knowledge about actual practices which were not sufficiently known so far. Findings and new additional recommendations will be included in a future PPR methodological guide exclusively suited for torrential context, which is currently still missing