Structural basis for substrate gripping and translocation by the ClpB AAA+ disaggregase.

Bacterial ClpB and yeast Hsp104 are homologous Hsp100 protein disaggregases that serve critical functions in proteostasis by solubilizing protein aggregates. Two AAA+ nucleotide binding domains (NBDs) power polypeptide translocation through a central channel comprised of a hexameric spiral of protomers that contact substrate via conserved pore-loop interactions. Here we report cryo-EM structures of a hyperactive ClpB variant bound to the model substrate, casein in the presence of slowly hydrolysable ATPγS, which reveal the translocation mechanism. Distinct substrate-gripping interactions are identified for NBD1 and NBD2 pore loops. A trimer of N-terminal domains define a channel entrance that binds the polypeptide substrate adjacent to the topmost NBD1 contact. NBD conformations at the seam interface reveal how ATP hydrolysis-driven substrate disengagement and re-binding are precisely tuned to drive a directional, stepwise translocation cycle

Patients with multiple sclerosis do not necessarily consume more alcohol or tobacco than the general population

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Exercise alters liver mitochondria phospholipidomic profile and mitochondrial activity in non-alcoholic steatohepatitis

Mitochondrial membrane lipid composition is a critical factor in non-alcoholic steatohepatitis (NASH). Exercise is the most prescribed therapeutic strategy against NASH and a potential modulator of lipid membrane. Thus, we aimed to analyze whether physical exercise exerted preventive (voluntary physical activity – VPA) and therapeutic (endurance training – ET) effect on NASH-induced mitochondrial membrane changes. Sprague-Dawley rats (n = 36) were divided into standard-diet sedentary (SS, n = 12), standard-diet VPA (SVPA, n = 6), high-fat diet sedentary (HS, n = 12) and high-fat diet VPA (HVPA, n = 6). After 9 weeks of diet-specific feeding, half of SS and HS group were engaged in an ET program for 8 weeks/5 day/week/1 h/day (SET, HET). Liver mitochondria were isolated for oxygen consumption and transmembrane-electric potential (ΔΨ) assays. Mitochondrial phospholipid classes and fatty acids were quantified through thin layer chromatography and gas chromatography, respectively, while cardiolipin (CL), phosphatidylcholine (PC) phosphatidylethanolamine (PE) and phosphatidylinositol (PI) molecular profile was determined by electrospray mass spectrometry. In parallel with histological signs of NASH, high-fat diet decreased PI, CL and PC/PE ratio, whereas PE and phosphatidic acid content increased in sedentary animals (HS vs. SS). Moreover, a decrease in linolelaidic, monounsaturated fatty acids content and an increase in saturated fatty acids (SFAS) were observed. Along with phospholipidomic alterations, HS animals showed a decrease in respiratory control ratio (RCR), ΔΨ and FCCP-induced uncoupling respiration (HS vs. SS). Both phospholipidomic (PC/PE, SFAS) and mitochondrial respiratory alterations were counteracted by exercise interventions. Exercise used as preventive (VPA) or therapeutic (ET) strategies preserved liver mitochondrial phospholipidomic profile and maintained mitochondrial function in a model of NASH

Mining Disaggregase Sequence Space to Safely Counter TDP-43, FUS, and α-Synuclein Proteotoxicity.

Hsp104 is an AAA+ protein disaggregase, which can be potentiated via diverse mutations in its autoregulatory middle domain (MD) to mitigate toxic misfolding of TDP-43, FUS, and α-synuclein implicated in fatal neurodegenerative disorders. Problematically, potentiated MD variants can exhibit off-target toxicity. Here, we mine disaggregase sequence space to safely enhance Hsp104 activity via single mutations in nucleotide-binding domain 1 (NBD1) or NBD2. Like MD variants, NBD variants counter TDP-43, FUS, and α-synuclein toxicity and exhibit elevated ATPase and disaggregase activity. Unlike MD variants, non-toxic NBD1 and NBD2 variants emerge that rescue TDP-43, FUS, and α-synuclein toxicity. Potentiating substitutions alter NBD1 residues that contact ATP, ATP-binding residues, or the MD. Mutating the NBD2 protomer interface can also safely ameliorate Hsp104. Thus, we disambiguate allosteric regulation of Hsp104 by several tunable structural contacts, which can be engineered to spawn enhanced therapeutic disaggregases with minimal off-target toxicity

Depósitos de zeolitas naturales de Cuba

Zeolite deposits exist in almost every province and region in Cuba. They are related to back-arc sequences from Cretaceous and Paleocene- Eocene volcanic arcs, and to top sequences of the axial arc zone from a Cretaceous volcanic arc, of which the latter developed only in the central part of Cuba. Due to the transformation of volcanic shards of medium-acid composition clinoptilolite, mordenite and less widespread montmorillonite originated. Clinoptilolite substitutes volcanic shards, and mordenite is formed after it

Melody recognition with learned edit distances

In a music recognition task, the classification of a new melody is often achieved by looking for the closest piece in a set of already known prototypes. The definition of a relevant similarity measure becomes then a crucial point. So far, the edit distance approach with a-priori fixed operation costs has been one of the most used to accomplish the task. In this paper, the application of a probabilistic learning model to both string and tree edit distances is proposed and is compared to a genetic algorithm cost fitting approach. The results show that both learning models outperform fixed-costs systems, and that the probabilistic approach is able to describe consistently the underlying melodic similarity model.This work was funded by the French ANR Marmota project, the Spanish PROSEMUS project (TIN2006-14932-C02), the research programme Consolider Ingenio 2010 (MIPRCV, CSD2007-00018), and the Pascal Network of Excellence

Mechanistic basis of an epistatic interaction reducing age at onset in hereditary spastic paraplegia

Many genetic neurological disorders exhibit variable expression within affected families, often exemplified by variations in disease age at onset. Epistatic effects (i.e. effects of modifier genes on the disease gene) may underlie this variation, but the mechanistic basis for such epistatic interactions is rarely understood. Here we report a novel epistatic interaction between SPAST and the contiguous gene DPY30, which modifies age at onset in hereditary spastic paraplegia, a genetic axonopathy. We found that patients with hereditary spastic paraplegia caused by genomic deletions of SPAST that extended into DPY30 had a significantly younger age at onset. We show that, like spastin, the protein encoded by SPAST, the DPY30 protein controls endosomal tubule fission, traffic of mannose 6-phosphate receptors from endosomes to the Golgi, and lysosomal ultrastructural morphology. We propose that additive effects on this pathway explain the reduced age at onset of hereditary spastic paraplegia in patients who are haploinsufficient for both genes.This work was supported by grants to E.R.; Project Grant from United States Spastic Paraplegia Foundation, UK Medical Research Council Project Grant [MR/M00046X/1], Project grant from NIHR Biomedical Research Centre at Addenbrooke’s Hospital, Wellcome Trust Senior Research Fellowship in Clinical Science [082381], Project Grant from Tom Wahlig Stiftung (project 33). J.E. and P.M. are supported by a Wellcome Trust Principal Research Fellowship Grant to Margaret S. Robinson [086598]. T.M.N. was supported by an MRC PhD studentship [G0800117]. B.W. is supported by the Tom Wahlig Advanced Fellowship, the German Federal Ministry of Education and Research (BMBF, 01GQ113), the Bavarian Ministry of Education and Culture, Sciences and Arts in the framework of the Bavarian Molecular Biosystems Research Network and ForIPS, and the Interdisciplinary Centre for Clinical Research (IZKF, University Hospital of Erlangen, N3 and F3). T.R. was supported by research grant DFG GRK2162/1 of the Deutsche Forschungsgemeinschaft. The study was also supported by the European Union within the 7th European Community Framework Program for Research and Technological Development through funding for the NEUROMICS network (F5-2012-305121 to L.S. and A.D.), the E-Rare Network NEUROLIPID (01GM1408B to R.S. and ANR-13-RARE-0003-02 to G.S.), and a Marie Curie International Outgoing Fellowship (grant PIOF-GA-2012-326681 to R.S. and L.S.). This work was further supported by the US National Institutes of Health (NIH) (grant 5R01NS072248 to R.S.), the German HSP-Selbsthilfegruppe e.V. (grant to R.S. and L.S.), and grants to C.B.: Project Grant from Tom Wahlig Stiftung (project 20), grant from the Stiftung für Pathobiochemie und Molekulare Diagnostik. CIMR is supported by a Wellcome Trust Strategic Award [100140] and Equipment Grant [093026]

VAMP4 directs synaptic vesicles to a pool that selectively maintains asynchronous neurotransmission

Synaptic vesicles in the brain harbor several soluble N-ethylmaleimide-sensitive-factor attachment protein receptor (SNARE) proteins. With the exception of synaptobrevin2, or VAMP2 (syb2), which is directly involved in vesicle fusion, the role of these SNAREs in neurotransmission is unclear. Here we show that in mice syb2 drives rapid Ca2+-dependent synchronous neurotransmission, whereas the structurally homologous SNARE protein VAMP4 selectively maintains bulk Ca2+-dependent asynchronous release. At inhibitory nerve terminals, up- or downregulation of VAMP4 causes a correlated change in asynchronous release. Biochemically, VAMP4 forms a stable complex with SNAREs syntaxin-1 and SNAP-25 that does not interact with complexins or synaptotagmin-1, proteins essential for synchronous neurotransmission. Optical imaging of individual synapses indicates that trafficking of VAMP4 and syb2 show minimal overlap. Taken together, these findings suggest that VAMP4 and syb2 diverge functionally, traffic independently and support distinct forms of neurotransmission. These results provide molecular insight into how synapses diversify their release properties by taking advantage of distinct synaptic vesicle–associated SNAREs