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AAA+ ATPase

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https://www.readbyqxmd.com/read/28712723/msp1-is-a-membrane-protein-dislocase-for-tail-anchored-proteins
#1
Matthew L Wohlever, Agnieszka Mateja, Philip T McGilvray, Kasey J Day, Robert J Keenan
Mislocalized tail-anchored (TA) proteins of the outer mitochondrial membrane are cleared by a newly identified quality control pathway involving the conserved eukaryotic protein Msp1 (ATAD1 in humans). Msp1 is a transmembrane AAA-ATPase, but its role in TA protein clearance is not known. Here, using purified components reconstituted into proteoliposomes, we show that Msp1 is both necessary and sufficient to drive the ATP-dependent extraction of TA proteins from the membrane. A crystal structure of the Msp1 cytosolic region modeled into a ring hexamer suggests that active Msp1 contains a conserved membrane-facing surface adjacent to a central pore...
July 20, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28710470/deviation-of-the-typical-aaa-substrate-threading-pore-prevents-fatal-protein-degradation-in-yeast-cdc48
#2
Masatoshi Esaki, Md Tanvir Islam, Naoki Tani, Teru Ogura
Yeast Cdc48 is a well-conserved, essential chaperone of ATPases associated with diverse cellular activity (AAA) proteins, which recognizes substrate proteins and modulates their conformations to carry out many cellular processes. However, the fundamental mechanisms underlying the diverse pivotal roles of Cdc48 remain unknown. Almost all AAA proteins form a ring-shaped structure with a conserved aromatic amino acid residue that is essential for proper function. The threading mechanism hypothesis suggests that this residue guides the intrusion of substrate proteins into a narrow pore of the AAA ring, thereby becoming unfolded...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28709027/singlet-oxygen-triggers-chloroplast-rupture-and-cell-death-in-the-zeaxanthin-epoxidase-defective-mutant-aba1-of-arabidopsis-thaliana-under-high-light-stress
#3
Álvaro Sánchez-Corrionero, Inmaculada Sánchez-Vicente, Sergio González-Pérez, Ascensión Corrales, Anja Krieger-Liszkay, Óscar Lorenzo, Juan B Arellano
The two Arabidopsis thaliana mutants, aba1 and max4, were previously identified as sharing a number of co-regulated genes with both the flu mutant and Arabidopsis cell suspension cultures exposed to high light (HL). On this basis, we investigated whether aba1 and max4 were generating high amounts of singlet oxygen ((1)O2) and activating (1)O2-mediated cell death. Thylakoids of aba1 produced twice as much (1)O2 as thylakoids of max4 and wild type (WT) plants when illuminated with strong red light. (1)O2 was measured using the spin probe 2,2,6,6-tetramethyl-4-piperidone hydrochloride...
July 4, 2017: Journal of Plant Physiology
https://www.readbyqxmd.com/read/28704538/intestinal-calcium-and-bile-salts-facilitate-germination-of-clostridium-difficile-spores
#4
Travis J Kochan, Madeline J Somers, Alyssa M Kaiser, Michelle S Shoshiev, Ada K Hagan, Jessica L Hastie, Nicole P Giordano, Ashley D Smith, Alyxandria M Schubert, Paul E Carlson, Philip C Hanna
Clostridium difficile (C. difficile) is an anaerobic gram-positive pathogen that is the leading cause of nosocomial bacterial infection globally. C. difficile infection (CDI) typically occurs after ingestion of infectious spores by a patient that has been treated with broad-spectrum antibiotics. While CDI is a toxin-mediated disease, transmission and pathogenesis are dependent on the ability to produce viable spores. These spores must become metabolically active (germinate) in order to cause disease. C. difficile spore germination occurs when spores encounter bile salts and other co-germinants within the small intestine, however, the germination signaling cascade is unclear...
July 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28700685/characterization-of-the-molecular-chaperone-clpb-from-the-pathogenic-spirochaete-leptospira-interrogans
#5
Joanna Krajewska, Anna Modrak-Wójcik, Zbigniew J Arent, Daniel Więckowski, Michal Zolkiewski, Agnieszka Bzowska, Sabina Kędzierska-Mieszkowska
Leptospira interrogans is a spirochaete responsible for leptospirosis in mammals. The molecular mechanisms of the Leptospira virulence remain mostly unknown. Recently, it has been demonstrated that an AAA+ chaperone ClpB (a member of the Hsp100 family) from L. interrogans (ClpBLi) is not only essential for survival of Leptospira under the thermal and oxidative stresses, but also during infection of a host. The aim of this study was to provide further insight into the role of ClpB in the pathogenic spirochaetes and explore its biochemical properties...
2017: PloS One
https://www.readbyqxmd.com/read/28691899/aggregation-of-a-hepatitis-c-virus-replicase-module-induced-by-ablation-of-p97-vcp
#6
Zhigang Yi, Zhenghong Yuan
Hijacking host membranes to assemble a membrane-associated viral replicase is a hallmark of almost all positive-strand RNA viruses. However, how the virus co-opts host factors to facilitate this energy-unfavourable process is incompletely understood. In a previous study, using hepatitis C virus (HCV) as a model and employing affinity purification of the viral replicase, we identified a valosin-containing protein (p97/VCP), a member of the ATPases associated with diverse cellular activities (AAA+ ATPase family), as a viral replicase-associated host factor...
July 10, 2017: Journal of General Virology
https://www.readbyqxmd.com/read/28689658/conformational-landscape-of-the-p28-bound-human-proteasome-regulatory-particle
#7
Ying Lu, Jiayi Wu, Yuanchen Dong, Shuobing Chen, Shuangwu Sun, Yong-Bei Ma, Qi Ouyang, Daniel Finley, Marc W Kirschner, Youdong Mao
The proteasome holoenzyme is activated by its regulatory particle (RP) consisting of two subcomplexes, the lid and the base. A key event in base assembly is the formation of a heterohexameric ring of AAA-ATPases, which is guided by at least four RP assembly chaperones in mammals: PAAF1, p28/gankyrin, p27/PSMD9, and S5b. Using cryogenic electron microscopy, we analyzed the non-AAA structure of the p28-bound human RP at 4.5 Å resolution and determined seven distinct conformations of the Rpn1-p28-AAA subcomplex within the p28-bound RP at subnanometer resolutions...
July 20, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28689657/wnt-dependent-inactivation-of-the-groucho-tle-co-repressor-by-the-hect-e3%C3%A2-ubiquitin-ligase-hyd-ubr5
#8
Joshua E Flack, Juliusz Mieszczanek, Nikola Novcic, Mariann Bienz
Extracellular signals are transduced to the cell nucleus by effectors that bind to enhancer complexes to operate transcriptional switches. For example, the Wnt enhanceosome is a multiprotein complex associated with Wnt-responsive enhancers through T cell factors (TCF) and kept silent by Groucho/TLE co-repressors. Wnt-activated β-catenin binds to TCF to overcome this repression, but how it achieves this is unknown. Here, we discover that this process depends on the HECT E3 ubiquitin ligase Hyd/UBR5, which is required for Wnt signal responses in Drosophila and human cell lines downstream of activated Armadillo/β-catenin...
July 20, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28676851/aaa-atpases-in-protein-degradation
#9
REVIEW
Ravikiran S Yedidi, Petra Wendler, Cordula Enenkel
Proteolytic machineries containing multisubunit protease complexes and AAA-ATPases play a key role in protein quality control and the regulation of protein homeostasis. In these protein degradation machineries, the proteolytically active sites are formed by either threonines or serines which are buried inside interior cavities of cylinder-shaped complexes. In eukaryotic cells, the proteasome is the most prominent protease complex harboring AAA-ATPases. To degrade protein substrates, the gates of the axial entry ports of the protease need to be open...
2017: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/28675036/asymmetric-conformational-transitions-in-aaa-biological-nanomachines-modulate-direction-dependent-substrate-protein-unfolding-mechanisms
#10
Abdolreza Javidialesaadi, George Stan
Powerful AAA+ biological nanomachines, such as ClpY, form hexameric ring structures, which selectively process abnormal proteins targeted for degradation by unfolding and threading them through a narrow central channel. The molecular details of this process are not yet fully understood. We perform Langevin dynamics simulations using a coarse-grained model of substrate proteins (SPs), Titin I27 and its V13P variant, threading through the ClpY pore. We probe the effect of ClpY surface heterogeneity and changes in pore width on SP orientation and the direction of applied force during SP unfolding...
July 18, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28659378/the-aaa-atpase-trip13-remodels-horma-domains-through-n-terminal-engagement-and-unfolding
#11
Qiaozhen Ye, Dong Hyun Kim, Ihsan Dereli, Scott C Rosenberg, Goetz Hagemann, Franz Herzog, Attila Tóth, Don W Cleveland, Kevin D Corbett
Proteins of the conserved HORMA domain family, including the spindle assembly checkpoint protein MAD2 and the meiotic HORMADs, assemble into signaling complexes by binding short peptides termed "closure motifs". The AAA+ ATPase TRIP13 regulates both MAD2 and meiotic HORMADs by disassembling these HORMA domain-closure motif complexes, but its mechanisms of substrate recognition and remodeling are unknown. Here, we combine X-ray crystallography and crosslinking mass spectrometry to outline how TRIP13 recognizes MAD2 with the help of the adapter protein p31(comet) We show that p31(comet) binding to the TRIP13 N-terminal domain positions the disordered MAD2 N-terminus for engagement by the TRIP13 "pore loops", which then unfold MAD2 in the presence of ATP N-terminal truncation of MAD2 renders it refractory to TRIP13 action in vitro, and in cells causes spindle assembly checkpoint defects consistent with loss of TRIP13 function...
June 28, 2017: EMBO Journal
https://www.readbyqxmd.com/read/28655825/a-plastid-protein-that-evolved-from-ubiquitin-and-is-required-for-apicoplast-protein-import-in-toxoplasma-gondii
#12
Justin D Fellows, Michael J Cipriano, Swati Agrawal, Boris Striepen
Apicomplexan parasites cause a variety of important infectious diseases, including malaria, toxoplasma encephalitis, and severe diarrhea due to Cryptosporidium Most apicomplexans depend on an organelle called the apicoplast which is derived from a red algal endosymbiont. The apicoplast is essential for the parasite as the compartment of fatty acid, heme, and isoprenoid biosynthesis. The majority of the approximate 500 apicoplast proteins are nucleus encoded and have to be imported across the four membranes that surround the apicoplast...
June 27, 2017: MBio
https://www.readbyqxmd.com/read/28648606/the-structure-of-the-r2tp-complex-defines-a-platform-for-recruiting-diverse-client-proteins-to-the-hsp90-molecular-chaperone-system
#13
Angel Rivera-Calzada, Mohinder Pal, Hugo Muñoz-Hernández, Juan R Luque-Ortega, David Gil-Carton, Gianluca Degliesposti, J Mark Skehel, Chrisostomos Prodromou, Laurence H Pearl, Oscar Llorca
The R2TP complex, comprising the Rvb1p-Rvb2p AAA-ATPases, Tah1p, and Pih1p in yeast, is a specialized Hsp90 co-chaperone required for the assembly and maturation of multi-subunit complexes. These include the small nucleolar ribonucleoproteins, RNA polymerase II, and complexes containing phosphatidylinositol-3-kinase-like kinases. The structure and stoichiometry of yeast R2TP and how it couples to Hsp90 are currently unknown. Here, we determine the 3D organization of yeast R2TP using sedimentation velocity analysis and cryo-electron microscopy...
July 5, 2017: Structure
https://www.readbyqxmd.com/read/28636814/arsenic-compromises-both-p97-and-proteasome-functions
#14
Joseph Tillotson, Christopher J Zerio, Bryan Harder, Andrew J Ambrose, Kevin S Jung, MinJin Kang, Donna D Zhang, Eli Chapman
Exposure to arsenic is a worldwide problem that affects more than 200 million people. The underlying mechanisms of arsenic toxicity have been difficult to ascertain due to arsenic's pleotropic effects. A number of recent investigations have shown that arsenic can compromise protein quality control through the ubiquitin proteasome system (UPS) or the endoplasmic reticulum associated protein degradation (ERAD) pathway. In this article, a link between arsenic and protein quality control is reported. Biochemical and cellular data demonstrate a misregulation of the ATPase cycle of the ATPase associated with various cellular activities (AAA+) chaperone, p97...
July 7, 2017: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/28629620/effects-of-inhibiting-vps4-support-a-general-role-for-escrts-in-extracellular-vesicle-biogenesis
#15
Charles E Jackson, Benjamin S Scruggs, Jean E Schaffer, Phyllis I Hanson
Extracellular vesicles (EVs) are proposed to play important roles in intercellular communication. Two classes of EVs can be distinguished based on their intracellular origin. Exosomes are generated within endosomes and released when these fuse with the plasma membrane, whereas ectosomes bud directly from the plasma membrane. Studies of EV function have been hindered by limited understanding of their biogenesis. Components of the endosomal sorting complex required for transport (ESCRT) machinery play essential roles in topologically equivalent processes at both the endosome and the plasma membrane and are consistently recovered in EVs, but whether they are generally required to produce EVs is still debated...
June 16, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28622508/saf-a-regulates-interphase-chromosome-structure-through-oligomerization-with-chromatin-associated-rnas
#16
Ryu-Suke Nozawa, Lora Boteva, Dinesh C Soares, Catherine Naughton, Alison R Dun, Adam Buckle, Bernard Ramsahoye, Peter C Bruton, Rebecca S Saleeb, Maria Arnedo, Bill Hill, Rory R Duncan, Sutherland K Maciver, Nick Gilbert
Higher eukaryotic chromosomes are organized into topologically constrained functional domains; however, the molecular mechanisms required to sustain these complex interphase chromatin structures are unknown. A stable matrix underpinning nuclear organization was hypothesized, but the idea was abandoned as more dynamic models of chromatin behavior became prevalent. Here, we report that scaffold attachment factor A (SAF-A), originally identified as a structural nuclear protein, interacts with chromatin-associated RNAs (caRNAs) via its RGG domain to regulate human interphase chromatin structures in a transcription-dependent manner...
June 15, 2017: Cell
https://www.readbyqxmd.com/read/28619716/ratchet-like-polypeptide-translocation-mechanism-of-the-aaa-disaggregase-hsp104
#17
Stephanie N Gates, Adam L Yokom, JiaBei Lin, Meredith E Jackrel, Alexandrea N Rizo, Nathan M Kendsersky, Courtney E Buell, Elizabeth A Sweeny, Korrie L Mack, Edward Chuang, Mariana P Torrente, Min Su, James Shorter, Daniel R Southworth
Hsp100 polypeptide translocases are conserved AAA+ machines that maintain proteostasis by unfolding aberrant and toxic proteins for refolding or proteolytic degradation. The Hsp104 disaggregase from S. cerevisiae solubilizes stress-induced amorphous aggregates and amyloid. The structural basis for substrate recognition and translocation is unknown. Using a model substrate (casein), we report cryo-EM structures at near-atomic resolution of Hsp104 in different translocation states. Substrate interactions are mediated by conserved, pore-loop tyrosines that contact an 80 Å-long unfolded polypeptide along the axial channel...
June 15, 2017: Science
https://www.readbyqxmd.com/read/28611991/substrate-discrimination-by-clpb-and-hsp104
#18
Danielle M Johnston, Marika Miot, Joel R Hoskins, Sue Wickner, Shannon M Doyle
ClpB of E. coli and yeast Hsp104 are homologous molecular chaperones and members of the AAA+ (ATPases Associated with various cellular Activities) superfamily of ATPases. They are required for thermotolerance and function in disaggregation and reactivation of aggregated proteins that form during severe stress conditions. ClpB and Hsp104 collaborate with the DnaK or Hsp70 chaperone system, respectively, to dissolve protein aggregates both in vivo and in vitro. In yeast, the propagation of prions depends upon Hsp104...
2017: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/28611990/structure-and-function-of-p97-and-pex1-6-type-ii-aaa-complexes
#19
REVIEW
Paul Saffert, Cordula Enenkel, Petra Wendler
Protein complexes of the Type II AAA+ (ATPases associated with diverse cellular activities) family are typically hexamers of 80-150 kDa protomers that harbor two AAA+ ATPase domains. They form double ring assemblies flanked by associated domains, which can be N-terminal, intercalated or C-terminal to the ATPase domains. Most prominent members of this family include NSF (N-ethyl-maleimide sensitive factor), p97/VCP (valosin-containing protein), the Pex1/Pex6 complex and Hsp104 in eukaryotes and ClpB in bacteria...
2017: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/28591576/regulation-of-rvb1-rvb2-by-a-domain-within-the-ino80-chromatin-remodeling-complex-implicates-the-yeast-rvbs-as-protein-assembly-chaperones
#20
Coral Y Zhou, Caitlin I Stoddard, Jonathan B Johnston, Michael J Trnka, Ignacia Echeverria, Eugene Palovcak, Andrej Sali, Alma L Burlingame, Yifan Cheng, Geeta J Narlikar
The hexameric AAA+ ATPases Rvb1 and Rvb2 (Rvbs) are essential for diverse processes ranging from metabolic signaling to chromatin remodeling, but their functions are unknown. While originally thought to act as helicases, recent proposals suggest that Rvbs act as protein assembly chaperones. However, experimental evidence for chaperone-like behavior is lacking. Here, we identify a potent protein activator of the Rvbs, a domain in the Ino80 ATPase subunit of the INO80 chromatin-remodeling complex, termed Ino80INS...
June 6, 2017: Cell Reports
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