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Inactivation of the TNFAIP3 gene, encoding the A20 protein, is associated with critical inflammatory diseases including multiple sclerosis, rheumatoid arthritis and Crohn's disease. However, the role of A20 in attenuating inflammatory signalling is unclear owing to paradoxical in vitro and in vivo findings. Here we utilize genetically engineered mice bearing mutations in the A20 ovarian tumour (OTU)-type deubiquitinase domain or in the zinc finger-4 (ZnF4) ubiquitin-binding motif to investigate these discrepancies. We find that phosphorylation of A20 promotes cleavage of Lys63-linked polyubiquitin chains by the OTU domain and enhances ZnF4-mediated substrate ubiquitination. Additionally, levels of linear ubiquitination dictate whether A20-deficient cells die in response to tumour necrosis factor. Mechanistically, linear ubiquitin chains preserve the architecture of the TNFR1 signalling complex by blocking A20-mediated disassembly of Lys63-linked polyubiquitin scaffolds. Collectively, our studies reveal molecular mechanisms whereby A20 deubiquitinase activity and ubiquitin binding, linear ubiquitination, and cellular kinases cooperate to regulate inflammation and cell death. The authors define molecular mechanisms by which distinct domains of the ubiquitin editing enzyme A20 contribute to the regulation of inflammation and cell death. Anti-apoptotic/anti-inflammatory actions of protein A20 Compromised function of the ubiquitin-editing enzyme A20 contributes to various inflammatory syndromes and autoimmune diseases including rheumatoid arthritis, multiple sclerosis, Crohn's disease and psoriasis. Here Ingrid Wertz et al. define the molecular mechanisms by which distinct domains of A20 contribute to the regulation of inflammation and cell death., Author(s): Ingrid E. Wertz [sup.1] [sup.2] , Kim Newton [sup.3] , Dhaya Seshasayee [sup.4] , Saritha Kusam [sup.2] [sup.12] , Cynthia Lam [sup.2] , Juan Zhang [sup.4] , Nataliya Popovych [...]

WA number of countries keep acid tar in the open air in spent quarries, barns, storage ponds (USA, UK, Netherlands, Belgium, Germany, Latvia, Slovenia, China) or near landfills (Zimbabwe). Storage of acid tars in open areas leads to an increase in regional environmental hazards. In Ukraine, acid tars are also stored in open spaces in storage ponds, in particular, in the city of Lviv near the municipal landfill. After the Lviv experimental petroleum-refining plant began to dispose of oil-refining waste at the Lviv city landfill, two ponds of acid tars were formed. Their total area is 6.8 ha. They were formed by constructing dams in the upper reaches of deep ravines, originating near the landfill. In total, about 300 thousand tons of acid tars have been accumulated in these earth basins. In 2004, the dams of the acid tar storage ponds got cracked. As a result, acidic water flows to the soil surface 1 km southwest of these storage ponds. Sampling for the study of acid tar migration was carried out from 4 sites of anthropogenic origin: 1 - acid tar storage pond No.1; 2 - acid tar storage pond No.2; 3 - technogenic water body at the foot of the landfill containing leacheate; 4 - technogenic water body on the north side of the landfill containing leacheate. The simulation was made by Surfer software. It was found that even after many years of their creation, a very high content of sulfuric acid is observed in the ponds (1,108- 3,862 mg / kg), and they remain a major environmental hazard. The simulation results made it possible to assess the migration of toxic components contained in the tar to the components of the biosphere - the hydrosphere and ecotope. It was established that, unlike other investigated technogenic water bodies, acid tars in the storage ponds have high content of petroleum products, sulphates, phosphates, suspended substances, and high rates of chemical oxygen demand. The high content of petroleum products suggests that acidic tars can be processed into liquid fuel by freeing them from excess water and salts. At the same time, these large quantities of petroleum products pose an environmental threat to soil and groundwater, thereby reducing regional environmental security. [ABSTRACT FROM AUTHOR]

The content of heavy metals, radionuclides, nitrates in edible mushrooms is a topical issue for many researchers in the world. However, such issues on edible mushrooms, in particular, Pleurotus ostreatus, which are found naturally within a large city, require more detailed studies because these mushrooms are used in human nutrition. It was found that in some areas, the cadmium content in the studied oyster mushroom specimens is three times higher than the maximum permissible concentration (0.092-0.095 mg / kg). The lead content in the fruiting bodies of oyster mushroom is in the range of maximum permissible concentration (MPC) and is 0.19-0.22 mg / kg. The content of mobile forms of copper exceeded the MPC only in two cases - 5.72 mg / kg and 5.06 mg / kg. The zinc content was 8.87-13.41 mg / kg with MPC being 10 mg / kg. The content of 137Cs was in the range of 0.095-0.1 Bq / kg and that of 90Sr was 0.3-0.4 Bq / kg, which does not exceed the MPC. The content of nitrates in the fruiting bodies of oyster mushrooms did not exceed the maximum permissible concentration of 50 mg / kg. Considering the data obtained on the content of heavy metals, radionuclides and nitrates in Pleurotus ostreatus, it should be noted that it is risky to eat such fruiting bodies that have developed in the urban-ecological environment. [ABSTRACT FROM AUTHOR]

A study was conducted to demonstrate the role of zinc found at millimolar concentrations in the secretory granule towards inhibition of human islet amyloid polypeptide (hIAPP) amyloid fibrillogenesis at concentrations similar to those found in the extracellular environment. The inhibition of the formation of aggregated and toxic forms of hIAPP by zinc provides insight into the possible mechanism for the linkage between deleterious mutations in the SLC30A8 zinc transporter, which transports zinc into the secretory granule, and type II diabetes.

The NMR spectroscopy technique is employed to analyze the various putative amyloidogenic regions present in the SEVI precursor peptide, [PAP.sub.248-286]. The peptide is shown to exhibit a highly disordered structure on being bound to the surface of the micelle.

Recently, a 39 amino acid peptide fragment from prostaticacid phosphatase has been isolated from seminal fluid that can enhanceinfectivity of the HIV virus by up to 4–5 orders of magnitude.PAP(248–286) is effective in enhancing HIV infectivity onlywhen it is aggregated into amyloid fibers termed SEVI. The polyphenolEGCG (epigallocatechin-3-gallate) has been shown to disrupt both SEVIformation and HIV promotion by SEVI, but the mechanism by which itaccomplishes this task is unknown. Here, we show that EGCG interactsspecifically with the side chains of monomeric PAP(248–286)in two regions (K251–R257 and N269–I277) of primarilycharged residues, particularly lysine. The specificity of interactionto these two sites is contrary to previous studies on the interactionof EGCG with other amyloidogenic proteins, which showed the nonspecificinteraction of EGCG with exposed backbone sites of unfolded amyloidogenicproteins. This interaction is specific to EGCG as the related gallocatechin(GC) molecule, which shows greatly decreased antiamyloid activity,exhibits minimal interaction with monomeric PAP(248–286). TheEGCG binding was shown to occur in two steps, with the initial formationof a weakly bound complex followed by a pH dependent formation ofa tightly bound complex. Experiments in which the lysine residuesof PAP(248–286) have been chemically modified suggest the tightlybound complex is created by Schiff-base formation with lysine residues.The results of this study could aid in the development of small moleculeinhibitors of SEVI and other amyloid proteins. [ABSTRACT FROM AUTHOR]

The atomic composition, local structure and coordination of flash evaporated Ge2S3 films and their changes induced by laser illumination and thermal annealing in vacuum were investigated by means of high resolution synchrotron radiation and X-ray photoelectron spectroscopy. The top surface and subsurface layers of the films are found to be enriched by Ge in comparison with the composition of target glass and contain oxygen and a significant contribution of physisorbed carbon. The influence of laser and thermal treatments of flash evaporated Ge-S films in vacuum on their composition is analyzed. The local atomic coordination obtained by curve fitting of Ge 3d, S 2p, O 1s and C 1s core level spectra is discussed in detail. [ABSTRACT FROM AUTHOR]

Microsomal cytochrome b5 (cytb5) is a membrane-bound protein that modulates the catalytic activity of its redox partner, cytochrome P4502B4 (cytP450). Here, we report the first structure of full-length rabbit ferric microsomal cytb5 (16 kDa), incorporated in two different membrane mimetics (detergent micelles and lipid bicelles). Differential line broadening of the cytb5NMRresonances and site-directed mutagenesis data were used to characterize the cytb5 interaction epitope recognized by ferric microsomal cytP450 (56 kDa). Subsequently, a datadriven docking algorithm, HADDOCK (high ambiguity driven biomolecular docking), was used to generate the structure of the complex between cytP4502B4 and cytb5 using experimentally derived restraints from NMR, mutagenesis, and the double mutant cycle data obtained on the full-length proteins. Our docking and experimental results point to the formation of a dynamic electron transfer complex between the acidic convex surface of cytb5 and the concave basic proximal surface of cytP4502B4. The majority of the binding energy for the complex is provided by interactions between residues on the C-helix and β-bulge of cytP450 and residues at the end of helix α4 of cytb5. The structure of the complex allows us to propose an interprotein electron transfer pathway involving the highly conserved Arg-125 on cytP450 serving as a salt bridge between the heme propionates of cytP450 and cytb5. We have also shown that the addition of a substrate to cytP450 likely strengthens the cytb5- cytP450 interaction. This study paves the way to obtaining valuable structural, functional, and dynamic information on membrane- bound complexes. [ABSTRACT FROM AUTHOR]

Abstract: Semen is the main vector for HIV transmission worldwide. Recently, a peptide fragment (PAP245-286) has been isolated from seminal fluid that dramatically enhances HIV infectivity by up to 4-5 orders of magnitude. PAP248-286 appears to enhance HIV infection by forming amyloid fibers known as SEVI, which are believed to enhance the attachment of the virus by bridging interactions between virion and host-cell membranes. We have solved the atomic-level resolution structure of the SEVI precursor PAP248-286 using NMR spectroscopy in SDS micelles, which serve as a model membrane system. PAP248-286, which does not disrupt membranes like most amyloid proteins, binds superficially to the surface of the micelle, in contrast to other membrane-disruptive amyloid peptides that generally penetrate into the core of the membrane. The structure of PAP248-286 is unlike most amyloid peptides in that PAP248-286 is mostly disordered when bound to the surface of the micelle, as opposed to the a-helical structures typically found of most amyloid proteins. The highly disordered nature of the SEVI peptide may explain the unique ability of SEVI amyloid fibers to enhance HIV infection as partially disordered amyloid fibers will have a greater capture radius for the virus than compact amyloid fibers. Two regions of nascent structure (an a-helix from V262-H270 and a dynamic α/310 helix from S279-L283) match the prediction of highly amyloidogenic sequences and may serve as nuclei for aggregation and amyloid fibril formation. The structure presented here can be used for the rational design of mutagenesis studies on SEV amyloid formation and viral infection enhancement. [ABSTRACT FROM AUTHOR]

Fragments of prostatic acid phosphatase (PAP248-286) in human semen dramatically increase HIV infection efficiency by increasing virus adhesion to target cells. PAP248-286 only enhances HIV infection in the form of amyloid aggregates termed SEVI (Semen Enhancer of Viral Infection), however monomeric PAP248-286 aggregates very slowly in isolation. It has therefore been suggested that SEVI fiber formation in vivo may be promoted by exogenous factors. We show here that a bacterially-produced extracellular amyloid (curli or Csg) acts as a catalytic agent for SEVI formation from PAP248-286 at low concentrations in vitro, producing fibers that retain the ability to enhance HIV (Human Immunodeficiency Virus) infection. Kinetic analysis of the cross-seeding effect shows an unusual pattern. Cross-seeding PAP248-286 with curli only moderately affects the nucleation rate while significantly enhancing the growth of fibers from existing nuclei. This pattern is in contrast to most previous observations of cross-seeding, which show cross-seeding partially bypasses the nucleation step but has little effect on fiber elongation. Seeding other amyloidogenic proteins (IAPP (islet amyloid polypeptide) and Aβ1-40) with curli showed varied results. Curli cross-seeding decreased the lag-time of IAPP amyloid formation but strongly inhibited IAPP elongation. Curli cross-seeding exerted a complicated concentration dependent effect on Aβ1-40 fibrillogenesis kinetics. Combined, these results suggest that the interaction of amyloidogenic proteins with preformed fibers of a different type can take a variety of forms and is not limited to epitaxial nucleation between proteins of similar sequence. The ability of curli fibers to interact with proteins of dissimilar sequences suggests cross-seeding may be a more general phenomenon than previously supposed.