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Qiu XR, Shen CR, Jiang LW, Ji P, Zhang Y, Hou WT, Zhang W, Shen H, An MM. Ssa1-targeted antibody prevents host invasion by Candida albicans. Front Microbiol 2023; 14:1182914. [PMID: 37560525 PMCID: PMC10407798 DOI: 10.3389/fmicb.2023.1182914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 06/20/2023] [Indexed: 08/11/2023] Open
Abstract
INTRODUCTION Candida albicans is a commensal fungus that colonizes most healthy individuals' skin and mucosal surfaces but can also cause life-threatening invasive infections, particularly in immunocompromised patients. Despite antifungal treatment availability, drug resistance is increasing, and mortality rates remain unacceptably high. Heat shock protein Ssa1, a conserved member of the Hsp70 family in yeast, is a novel invasin that binds to host cell cadherins, induces host cell endocytosis, and enables C. albicans to cause maximal damage to host cells and induces disseminated and oropharyngeal disease. RESULT Here we discovered a mouse monoclonal antibody (mAb 13F4) that targeting C. albicans Ssa1 with high affinity (EC50 = 39.78 ng/mL). mAb 13F4 prevented C. albicans from adhering to and invading human epithelial cells, displayed antifungal activity, and synergized with fluconazole in proof of concept in vivo studies. mAb 13F4 significantly prolonged the survival rate of the hematogenous disseminated candidiasis mice to 75%. We constructed a mAb 13F4 three-dimensional structure using homology modeling methods and found that the antigen-binding fragment (Fab) interacts with the Ssa1 N-terminus. DISCUSSION These results suggest that blocking Ssa1 cell surface function may effectively control invasive C. albicans infections and provide a potential new treatment strategy for invasive fungal infections.
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Affiliation(s)
- Xi-Ran Qiu
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Chen-Rui Shen
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Li-Wen Jiang
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Peng Ji
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yu Zhang
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Wei-Tong Hou
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Wen Zhang
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Hui Shen
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Mao-Mao An
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
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2
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Matias AC, Matos J, Dohmen RJ, Ramos PC. Hsp70 and Hsp110 Chaperones Promote Early Steps of Proteasome Assembly. Biomolecules 2022; 13:biom13010011. [PMID: 36671396 PMCID: PMC9855889 DOI: 10.3390/biom13010011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Whereas assembly of the 20S proteasome core particle (CP) in prokaryotes apparently occurs spontaneously, the efficiency of this process in eukaryotes relies on the dedicated assembly chaperones Ump1, Pba1-Pba2, and Pba3-Pba4. For mammals, it was reported that CP assembly initiates with formation of a complete α-ring that functions as a template for β subunit incorporation. By contrast, we were not able to detect a ring composed only of a complete set of α subunits in S. cerevisiae. Instead, we found that the CP subunits α1, α2, and α4 each form independent small complexes. Purification of such complexes containing α4 revealed the presence of chaperones of the Hsp70/Ssa and Hsp110/Sse families. Consistently, certain small complexes containing α1, α2, and α4 were not formed in strains lacking these chaperones. Deletion of the SSE1 gene in combination with deletions of PRE9 (α3), PBA3, or UMP1 genes resulted in severe synthetic growth defects, high levels of ubiquitin-conjugates, and an accumulation of distinct small complexes with α subunits. Our study shows that Hsp70 and Hsp110 chaperones cooperate to promote the folding of individual α subunits and/or their assembly with other CP subunits, Ump1, and Pba1-Pba4 in subsequent steps.
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Affiliation(s)
- Ana C. Matias
- Center of Molecular Biosciences, Institute for Genetics, Department of Biology, Faculty of Natural Sciences and Mathematics, University of Cologne, 50674 Cologne, Germany
- Departamento de Química e Bioquímica, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 8000-117 Faro, Portugal
| | - Joao Matos
- Departamento de Química e Bioquímica, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 8000-117 Faro, Portugal
| | - R. Jürgen Dohmen
- Center of Molecular Biosciences, Institute for Genetics, Department of Biology, Faculty of Natural Sciences and Mathematics, University of Cologne, 50674 Cologne, Germany
- Correspondence: (R.J.D.); (P.C.R.)
| | - Paula C. Ramos
- Center of Molecular Biosciences, Institute for Genetics, Department of Biology, Faculty of Natural Sciences and Mathematics, University of Cologne, 50674 Cologne, Germany
- Departamento de Química e Bioquímica, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 8000-117 Faro, Portugal
- Correspondence: (R.J.D.); (P.C.R.)
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3
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Nitika, Porter CM, Truman AW, Truttmann MC. Post-translational modifications of Hsp70 family proteins: Expanding the chaperone code. J Biol Chem 2020; 295:10689-10708. [PMID: 32518165 PMCID: PMC7397107 DOI: 10.1074/jbc.rev120.011666] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/08/2020] [Indexed: 02/01/2023] Open
Abstract
Cells must be able to cope with the challenge of folding newly synthesized proteins and refolding those that have become misfolded in the context of a crowded cytosol. One such coping mechanism that has appeared during evolution is the expression of well-conserved molecular chaperones, such as those that are part of the heat shock protein 70 (Hsp70) family of proteins that bind and fold a large proportion of the proteome. Although Hsp70 family chaperones have been extensively examined for the last 50 years, most studies have focused on regulation of Hsp70 activities by altered transcription, co-chaperone "helper" proteins, and ATP binding and hydrolysis. The rise of modern proteomics has uncovered a vast array of post-translational modifications (PTMs) on Hsp70 family proteins that include phosphorylation, acetylation, ubiquitination, AMPylation, and ADP-ribosylation. Similarly to the pattern of histone modifications, the histone code, this complex pattern of chaperone PTMs is now known as the "chaperone code." In this review, we discuss the history of the Hsp70 chaperone code, its currently understood regulation and functions, and thoughts on what the future of research into the chaperone code may entail.
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Affiliation(s)
- Nitika
- Department of Biological Sciences, University of North Carolina, Charlotte, North Carolina, USA
| | - Corey M Porter
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Andrew W Truman
- Department of Biological Sciences, University of North Carolina, Charlotte, North Carolina, USA
| | - Matthias C Truttmann
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
- Geriatrics Center, University of Michigan, Ann Arbor, Michigan, USA
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4
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Doyle SM, Hoskins JR, Kravats AN, Heffner AL, Garikapati S, Wickner S. Intermolecular Interactions between Hsp90 and Hsp70. J Mol Biol 2019; 431:2729-46. [PMID: 31125567 DOI: 10.1016/j.jmb.2019.05.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 12/27/2022]
Abstract
Members of the Hsp90 and Hsp70 families of molecular chaperones are imp\ortant for the maintenance of protein homeostasis and cellular recovery following environmental stresses, such as heat and oxidative stress. Moreover, the two chaperones can collaborate in protein remodeling and activation. In higher eukaryotes, Hsp90 and Hsp70 form a functionally active complex with Hop (Hsp90-Hsp70 organizing protein) acting as a bridge between the two chaperones. In bacteria, which do not contain a Hop homolog, Hsp90 and Hsp70, DnaK, directly interact during protein remodeling. Although yeast possesses a Hop-like protein, Sti1, Hsp90, and Hsp70 can directly interact in yeast in the absence of Sti1. Previous studies showed that residues in the middle domain of Escherichia coli Hsp90 are important for interaction with the J-protein binding region of DnaK. The results did not distinguish between the possibility that (i) these sites were involved in direct interaction and (ii) the residues in these sites participate in conformational changes which are transduced to other sites on Hsp90 and DnaK that are involved in the direct interaction. Here we show by crosslinking experiments that the direct interaction is between a site in the middle domain of Hsp90 and the J-protein binding site of Hsp70 in both E. coli and yeast. Moreover, J-protein promotes the Hsp70-Hsp90 interaction in the presence of ATP, likely by converting Hsp70 into the ADP-bound conformation. The identification of the protein-protein interaction site is anticipated to lead to a better understanding of the collaboration between the two chaperones in protein remodeling.
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5
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Schopf FH, Huber EM, Dodt C, Lopez A, Biebl MM, Rutz DA, Mühlhofer M, Richter G, Madl T, Sattler M, Groll M, Buchner J. The Co-chaperone Cns1 and the Recruiter Protein Hgh1 Link Hsp90 to Translation Elongation via Chaperoning Elongation Factor 2. Mol Cell 2019; 74:73-87.e8. [PMID: 30876805 DOI: 10.1016/j.molcel.2019.02.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/17/2018] [Accepted: 02/07/2019] [Indexed: 12/31/2022]
Abstract
The Hsp90 chaperone machinery in eukaryotes comprises a number of distinct accessory factors. Cns1 is one of the few essential co-chaperones in yeast, but its structure and function remained unknown. Here, we report the X-ray structure of the Cns1 fold and NMR studies on the partly disordered, essential segment of the protein. We demonstrate that Cns1 is important for maintaining translation elongation, specifically chaperoning the elongation factor eEF2. In this context, Cns1 interacts with the novel co-factor Hgh1 and forms a quaternary complex together with eEF2 and Hsp90. The in vivo folding and solubility of eEF2 depend on the presence of these proteins. Chaperoning of eEF2 by Cns1 is essential for yeast viability and requires a defined subset of the Hsp90 machinery as well as the identified eEF2 recruiting factor Hgh1.
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Affiliation(s)
- Florian H Schopf
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Eva M Huber
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Christopher Dodt
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Abraham Lopez
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Maximilian M Biebl
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Daniel A Rutz
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Moritz Mühlhofer
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Gesa Richter
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany; Gottfried Schatz Research Center, Medical University of Graz, 8036 Graz, Austria
| | - Tobias Madl
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany; Gottfried Schatz Research Center, Medical University of Graz, 8036 Graz, Austria; BioTechMed-Graz, 8010 Graz, Austria
| | - Michael Sattler
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Michael Groll
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Johannes Buchner
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany.
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6
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Xue YL, Zhang Q, Sun Y, Zhou X, Hurley IP, Jones GW, Song Y. Using steered molecular dynamics to study the interaction between ADP and the nucleotide-binding domain of yeast Hsp70 protein Ssa1. J Comput Aided Mol Des 2018; 32:1217-1227. [PMID: 30392073 DOI: 10.1007/s10822-018-0136-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 07/19/2018] [Indexed: 11/25/2022]
Abstract
Genetics experiments have identified six mutations located in the subdomain IA (A17V, R23H, G32D, G32S, R34K, V372I) of Ssa1 that influence propagation of the yeast [PSI+] prion. However, the underlining molecular mechanisms of these mutations are still unclear. The six mutation sites are present in the IA subdomain of the nucleotide-binding domain (NBD). The ATPase subdomain IA is a critical mediator of inter-domain allostery in Hsp70 molecular chaperones, so the mutation and changes in this subdomain may influence the function of the substrate-binding domain. In addition, ADP release is a rate-limiting step of the ATPase cycle and dysregulation of the ATPase cycle influences the propagation of the yeast [PSI+] prion. In this work, steered molecular dynamics (SMD) simulations were performed to explore the interaction between ADP and NBD. Results suggest that during the SMD simulations, hydrophobic interactions are predominant and variations in the binding state of ADP within the mutants is a potential reason for in vivo effects on yeast [PSI+] prion propagation. Additionally, we identify the primary residues in the ATPase domain that directly constitute the main hydrophobic interaction network and directly influence the ADP interaction state with the NBD of Ssa1. Furthermore, this in silico analysis reaffirms the importance of previously experimentally-determined residues in the Hsp70 ATPase domain involved in ADP binding and also identifies new residues potentially involved in this process.
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Affiliation(s)
- You-Lin Xue
- School of Environmental Science, College of Environment, Liaoning University, No. 66 Chongshan Middle Road, Huanggu District, Shenyang, 110036, Liaoning, China.,College of Light Industry, Liaoning University, Shenyang, 110036, China
| | - Qiaoshi Zhang
- School of Environmental Science, College of Environment, Liaoning University, No. 66 Chongshan Middle Road, Huanggu District, Shenyang, 110036, Liaoning, China
| | - Yuna Sun
- School of Environmental Science, College of Environment, Liaoning University, No. 66 Chongshan Middle Road, Huanggu District, Shenyang, 110036, Liaoning, China
| | - Xiaohong Zhou
- School of Environmental Science, College of Environment, Liaoning University, No. 66 Chongshan Middle Road, Huanggu District, Shenyang, 110036, Liaoning, China
| | - Ian P Hurley
- Centre for Biomedical Science Research, School of Clinical and Applied Sciences, Faculty of Health and Social Sciences, Leeds Beckett University, Leeds, LS13HE, UK
| | - Gary W Jones
- Centre for Biomedical Science Research, School of Clinical and Applied Sciences, Faculty of Health and Social Sciences, Leeds Beckett University, Leeds, LS13HE, UK
| | - Youtao Song
- School of Environmental Science, College of Environment, Liaoning University, No. 66 Chongshan Middle Road, Huanggu District, Shenyang, 110036, Liaoning, China.
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7
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Griffith AA, Boutin J, Holmes W. A highly efficient, one-step purification of the Hsp70 chaperone Ssa1. Protein Expr Purif 2018; 152:56-63. [PMID: 30030046 DOI: 10.1016/j.pep.2018.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 07/13/2018] [Accepted: 07/14/2018] [Indexed: 11/16/2022]
Abstract
Chaperone proteins are required to maintain the overall fold and function of proteins in the cell. As part of the Hsp70 family, Ssa1 acts to maintain cellular proteostasis through a variety of diverse pathways aimed to preserve the native conformation of target proteins, thereby preventing aggregation and future states of cellular toxicity. Studying the structural dynamics of Ssa1 in vitro is essential to determining their precise mechanisms and requires the development of purification methods that result in highly pure chaperones. Current methods of expressing and purifying Ssa1 utilize affinity tagged constructs expressed in Escherichia coli, however, expression in an exogenous source produces proteins that lack post-translational modifications leading to undesired structural and functional effects. Current protocols to purify Ssa1 from Saccharomyces cerevisiae require large amounts of starting material, multiple steps of chromatography, and result in low yield. Our objective was to establish a small-scale purification of Ssa1 expressed from its endogenous source, Saccharomyces cerevisiae, with significant yield and purity. We utilized a protein A affinity tag that was previously used to purify large protein complexes from yeast, combined with magnetic Dynabeads that are conjugated with rabbit immunoglobulin G (IgG). Our results show that we can produce native, highly pure, active Ssa1 via this one-step purification with minimal amounts of starting material, and this Ssa1-protein A fusion does not alter cellular phenotypes. This methodology is a significant improvement in Ssa1 purification and will facilitate future experiments that will elucidate the biochemical and biophysical properties of Hsp70 chaperones.
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8
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Kravats AN, Hoskins JR, Reidy M, Johnson JL, Doyle SM, Genest O, Masison DC, Wickner S. Functional and physical interaction between yeast Hsp90 and Hsp70. Proc Natl Acad Sci U S A 2018; 115:E2210-9. [PMID: 29463764 DOI: 10.1073/pnas.1719969115] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Heat shock protein 90 (Hsp90) is a highly conserved ATP-dependent molecular chaperone that is essential in eukaryotes. It is required for the activation and stabilization of more than 200 client proteins, including many kinases and steroid hormone receptors involved in cell-signaling pathways. Hsp90 chaperone activity requires collaboration with a subset of the many Hsp90 cochaperones, including the Hsp70 chaperone. In higher eukaryotes, the collaboration between Hsp90 and Hsp70 is indirect and involves Hop, a cochaperone that interacts with both Hsp90 and Hsp70. Here we show that yeast Hsp90 (Hsp82) and yeast Hsp70 (Ssa1), directly interact in vitro in the absence of the yeast Hop homolog (Sti1), and identify a region in the middle domain of yeast Hsp90 that is required for the interaction. In vivo results using Hsp90 substitution mutants showed that several residues in this region were important or essential for growth at high temperature. Moreover, mutants in this region were defective in interaction with Hsp70 in cell lysates. In vitro, the purified Hsp82 mutant proteins were defective in direct physical interaction with Ssa1 and in protein remodeling in collaboration with Ssa1 and cochaperones. This region of Hsp90 is also important for interactions with several Hsp90 cochaperones and client proteins, suggesting that collaboration between Hsp70 and Hsp90 in protein remodeling may be modulated through competition between Hsp70 and Hsp90 cochaperones for the interaction surface.
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9
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Kaimal JM, Kandasamy G, Gasser F, Andréasson C. Coordinated Hsp110 and Hsp104 Activities Power Protein Disaggregation in Saccharomyces cerevisiae. Mol Cell Biol 2017; 37:e00027-17. [PMID: 28289075 DOI: 10.1128/MCB.00027-17] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/06/2017] [Indexed: 01/16/2023] Open
Abstract
Protein aggregation is intimately associated with cellular stress and is accelerated during aging, disease, and cellular dysfunction. Yeast cells rely on the ATP-consuming chaperone Hsp104 to disaggregate proteins together with Hsp70. Hsp110s are ancient and abundant chaperones that form complexes with Hsp70. Here we provide in vivo data showing that the Saccharomyces cerevisiae Hsp110s Sse1 and Sse2 are essential for Hsp104-dependent protein disaggregation. Following heat shock, complexes of Hsp110 and Hsp70 are recruited to protein aggregates and function together with Hsp104 in the disaggregation process. In the absence of Hsp110, targeting of Hsp70 and Hsp104 to the aggregates is impaired, and the residual Hsp104 that still reaches the aggregates fails to disaggregate. Thus, coordinated activities of both Hsp104 and Hsp110 are required to reactivate aggregated proteins. These findings have important implications for the understanding of how eukaryotic cells manage misfolded and amyloid proteins.
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10
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Tripathi A, Mandon EC, Gilmore R, Rapoport TA. Two alternative binding mechanisms connect the protein translocation Sec71-Sec72 complex with heat shock proteins. J Biol Chem 2017; 292:8007-8018. [PMID: 28286332 DOI: 10.1074/jbc.m116.761122] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 03/09/2017] [Indexed: 12/20/2022] Open
Abstract
The biosynthesis of many eukaryotic proteins requires accurate targeting to and translocation across the endoplasmic reticulum membrane. Post-translational protein translocation in yeast requires both the Sec61 translocation channel, and a complex of four additional proteins: Sec63, Sec62, Sec71, and Sec72. The structure and function of these proteins are largely unknown. This pathway also requires the cytosolic Hsp70 protein Ssa1, but whether Ssa1 associates with the translocation machinery to target protein substrates to the membrane is unclear. Here, we use a combined structural and biochemical approach to explore the role of Sec71-Sec72 subcomplex in post-translational protein translocation. To this end, we report a crystal structure of the Sec71-Sec72 complex, which revealed that Sec72 contains a tetratricopeptide repeat (TPR) domain that is anchored to the endoplasmic reticulum membrane by Sec71. We also determined the crystal structure of this TPR domain with a C-terminal peptide derived from Ssa1, which suggests how Sec72 interacts with full-length Ssa1. Surprisingly, Ssb1, a cytoplasmic Hsp70 that binds ribosome-associated nascent polypeptide chains, also binds to the TPR domain of Sec72, even though it lacks the TPR-binding C-terminal residues of Ssa1. We demonstrate that Ssb1 binds through its ATPase domain to the TPR domain, an interaction that leads to inhibition of nucleotide exchange. Taken together, our results suggest that translocation substrates can be recruited to the Sec71-Sec72 complex either post-translationally through Ssa1 or co-translationally through Ssb1.
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Affiliation(s)
- Arati Tripathi
- From the Howard Hughes Medical Institute and the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115 and
| | - Elisabet C Mandon
- the Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Reid Gilmore
- the Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Tom A Rapoport
- From the Howard Hughes Medical Institute and the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115 and
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11
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Hu W, Wu H, Zhang H, Gong W, Perrett S. Resonance assignments for the substrate binding domain of Hsp70 chaperone Ssa1 from Saccharomyces cerevisiae. Biomol NMR Assign 2015; 9:329-332. [PMID: 25682100 DOI: 10.1007/s12104-015-9603-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/09/2015] [Indexed: 06/04/2023]
Abstract
Hsp70 chaperone proteins play crucial roles in the cell. Extensive structural and functional studies have been performed for bacterial and mammalian Hsp70s. Ssa1 from Saccharomyces cerevisiae is a member of the Hsp70 family. In vivo and biochemical studies on Ssa1 have revealed that it regulates prion propagation and the cell cycle. However, no structural data has been obtained for Ssa1 up to now. Here we report the almost complete (96 %) (1)H, (13)C, (15)N backbone and side chain NMR assignment of the 18.8 kDa Ssa1 substrate binding domain. The construct includes residues 382-554, which corresponds to the entire substrate binding domain and two following α-helices in homologous structures. The secondary structure predicted from the assigned chemical shifts is consistent with that of homologous Hsp70 substrate binding domains.
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Affiliation(s)
- Wanhui Hu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Huiwen Wu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Hong Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Weibin Gong
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Sarah Perrett
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
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12
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Mendoza AS, Dorce J, Peng Y, French BA, Tillman B, Li J, French SW. Levels of metacaspase1 and chaperones related to protein quality control in alcoholic and nonalcoholic steatohepatitis. Exp Mol Pathol 2014; 98:65-72. [PMID: 25526666 DOI: 10.1016/j.yexmp.2014.12.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 12/13/2014] [Indexed: 12/15/2022]
Abstract
Efficient management of misfolded or aggregated proteins in ASH and NASH is crucial for continued hepatic viability. Cellular protein quality control systems play an important role in the pathogenesis and progression of ASH and NASH. In a recent study, elevated Mca1 expression counteracted aggregation and accumulation of misfolded proteins and extended the life span of the yeast Saccharomyces cerevisiae (Hill et al, 2014). Mca1 may also associate with Ssa1 and Hsp104 in disaggregation and fragmentation of aggregated proteins and their subsequent degradation through the ER-associated degradation (ERAD) pathway. If degradation is not available, protection of the cellular environment from a misfolded protein is accomplished by its sequestration into two distinct inclusion bodies (Kaganovich et al., 2008) called the JUNQ (JUxta Nuclear Quality control compartment) and the IPOD (Insoluble Protein Deposit). Mca1, Hsp104, Hsp40, Ydj1, Ssa1, VCP/p97, and p62 all play important roles in protein quality control systems. This study aims to measure the expression of Mca1 and related chaperones involved in protein quality control in alcoholic steatohepatitis (ASH), and nonalcoholic steatohepatitis (NASH) compared with normal control liver biopsies. Mca1, Hsp104, Hsp40, Ydj1, Ssa1, VCP/p97, and p62 expressions were measured in three to six formalin-fixed paraffin embedded ASH and NASH liver biopsies and control normal liver specimens by immunofluorescence staining and quantified by immunofluorescence intensity. Mca1, Hsp104, Ydj1 and p62 were significantly upregulated compared to control (p<0.05) in ASH specimens. Hsp40 and VCP/p97 were also uptrending in ASH. In NASH, the only significant difference was the increased expression of Hsp104 compared to control (p<0.05). Ssa1 levels were uptrending in both ASH and NASH specimens. The upregulation of Mca1, Hsp104, Ydj1 and p62 in ASH may be elicited as a response to the chronic exposure of the hepatocytes to the toxicity of alcohol. Recruitment of Mca1, Hsp104, Ydj1 and p62 may indicate that autophagy, the ERAD, JUNQ, and IPOD systems are active in ASH. Whereas in NASH, elevated Hsp104 and uptrending Ssa1 levels may indicate that autophagy and IPOD may be the only active protein quality control systems involved.
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Affiliation(s)
- Alejandro S Mendoza
- LA Biomed, Department of Pathology, Harbor UCLA Medical Center, Torrance, CA, United States
| | - Jacques Dorce
- LA Biomed, Department of Pathology, Harbor UCLA Medical Center, Torrance, CA, United States
| | - Yue Peng
- LA Biomed, Department of Pathology, Harbor UCLA Medical Center, Torrance, CA, United States
| | - Barbara A French
- LA Biomed, Department of Pathology, Harbor UCLA Medical Center, Torrance, CA, United States
| | - Brittany Tillman
- LA Biomed, Department of Pathology, Harbor UCLA Medical Center, Torrance, CA, United States
| | - Jun Li
- LA Biomed, Department of Pathology, Harbor UCLA Medical Center, Torrance, CA, United States
| | - Samuel W French
- LA Biomed, Department of Pathology, Harbor UCLA Medical Center, Torrance, CA, United States
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Kabani M, Martineau CN. Multiple hsp70 isoforms in the eukaryotic cytosol: mere redundancy or functional specificity? Curr Genomics 2011; 9:338-248. [PMID: 19471609 PMCID: PMC2685646 DOI: 10.2174/138920208785133280] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 05/15/2008] [Accepted: 05/19/2008] [Indexed: 12/30/2022] Open
Abstract
Hsp70 molecular chaperones play a variety of functions in every organism, cell type and organelle, and their activities have been implicated in a number of human pathologies, ranging from cancer to neurodegenerative diseases. The functions, regulations and structure of Hsp70s were intensively studied for about three decades, yet much still remains to be learned about these essential folding enzymes. Genome sequencing efforts revealed that most genomes contain multiple members of the Hsp70 family, some of which co-exist in the same cellular compartment. For example, the human cytosol and nucleus contain six highly homologous Hsp70 proteins while the yeast Saccharomyces cerevisiae contains four canonical Hsp70s and three fungal-specific ribosome-associated and specialized Hsp70s. The reasons and significance of the requirement for multiple Hsp70s is still a subject of debate. It has been postulated for a long time that these Hsp70 isoforms are functionally redundant and differ only by their spatio-temporal expression patterns. However, several studies in yeast and higher eukaryotic organisms challenged this widely accepted idea by demonstrating functional specificity among Hsp70 isoforms. Another element of complexity is brought about by specific cofactors, such as Hsp40s or nucleotide exchange factors that modulate the activity of Hsp70s and their binding to client proteins. Hence, a dynamic network of chaperone/co-chaperone interactions has evolved in each organism to efficiently take advantage of the multiple cellular roles Hsp70s can play. We summarize here our current knowledge of the functions and regulations of these molecular chaperones, and shed light on the known functional specificities among isoforms.
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Affiliation(s)
- Mehdi Kabani
- Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, Bât. 34, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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