1
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Nematode CDC-37 and DNJ-13 form complexes and can interact with HSP-90. Sci Rep 2021; 11:21346. [PMID: 34725424 PMCID: PMC8560915 DOI: 10.1038/s41598-021-00885-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 10/18/2021] [Indexed: 12/02/2022] Open
Abstract
The molecular chaperones Hsc70 and Hsp90 are required for proteostasis control and specific folding of client proteins in eukaryotic and prokaryotic organisms. Especially in eukaryotes these ATP-driven molecular chaperones are interacting with cofactors that specify the client spectrum and coordinate the ATPase cycles. Here we find that a Hsc70-cofactor of the Hsp40 family from nematodes, DNJ-13, directly interacts with the kinase-specific Hsp90-cofactor CDC-37. The interaction is specific for DNJ-13, while DNJ-12 another DnaJ-like protein of C. elegans, does not bind to CDC-37 in a similar manner. Analytical ultracentrifugation is employed to show that one CDC-37 molecule binds to a dimeric DNJ-13 protein with low micromolar affinity. We perform cross-linking studies with mass spectrometry to identify the interaction site and obtain specific cross-links connecting the N-terminal J-domain of DNJ-13 with the N-terminal domain of CDC-37. Further AUC experiments reveal that both, the N-terminal part of CDC-37 and the C-terminal domain of CDC-37, are required for efficient interaction. Furthermore, the presence of DNJ-13 strengthens the complex formation between CDC-37 and HSP-90 and modulates the nucleotide-dependent effects. These findings on the interaction between Hsp40 proteins and Hsp90-cofactors provide evidence for a more intricate interaction between the two chaperone systems during client processing.
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2
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Comparative analysis of the coordinated motion of Hsp70s from different organelles observed by single-molecule three-color FRET. Proc Natl Acad Sci U S A 2021; 118:2025578118. [PMID: 34389669 DOI: 10.1073/pnas.2025578118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cellular function depends on the correct folding of proteins inside the cell. Heat-shock proteins 70 (Hsp70s), being among the first molecular chaperones binding to nascently translated proteins, aid in protein folding and transport. They undergo large, coordinated intra- and interdomain structural rearrangements mediated by allosteric interactions. Here, we applied a three-color single-molecule Förster resonance energy transfer (FRET) combined with three-color photon distribution analysis to compare the conformational cycle of the Hsp70 chaperones DnaK, Ssc1, and BiP. By capturing three distances simultaneously, we can identify coordinated structural changes during the functional cycle. Besides the known conformations of the Hsp70s with docked domains and open lid and undocked domains with closed lid, we observed additional intermediate conformations and distance broadening, suggesting flexibility of the Hsp70s in adopting the states in a coordinated fashion. Interestingly, the difference of this distance broadening varied between DnaK, Ssc1, and BiP. Study of their conformational cycle in the presence of substrate peptide and nucleotide exchange factors strengthened the observation of additional conformational intermediates, with BiP showing coordinated changes more clearly compared to DnaK and Ssc1. Additionally, DnaK and BiP were found to differ in their selectivity for nucleotide analogs, suggesting variability in the recognition mechanism of their nucleotide-binding domains for the different nucleotides. By using three-color FRET, we overcome the limitations of the usual single-distance approach in single-molecule FRET, allowing us to characterize the conformational space of proteins in higher detail.
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3
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Abstract
Cells and organisms grow old and die. We develop a biophysical model of the mechanism. Young cells are kept healthy by the positive processes of protein synthesis, degradation, and chaperoning (the activity of keeping proteins properly folded). But, with age, negative processes increase: Oxidative damage accumulates randomly in the cell’s proteins, healthy synthesis and degradation slow down, and—like overfilled garbage cans—chaperone capacity is exceeded. The chaperones are distracted trying to fold irreversibly damaged proteins, leading to accumulating misfolded and aggregated proteins in the cell. The tipping point to death happens when the negative overwhelms the positive. The model makes several quantitative predictions of the life span of the worm Caenorhabditis elegans. What molecular processes drive cell aging and death? Here, we model how proteostasis—i.e., the folding, chaperoning, and maintenance of protein function—collapses with age from slowed translation and cumulative oxidative damage. Irreparably damaged proteins accumulate with age, increasingly distracting the chaperones from folding the healthy proteins the cell needs. The tipping point to death occurs when replenishing good proteins no longer keeps up with depletion from misfolding, aggregation, and damage. The model agrees with experiments in the worm Caenorhabditis elegans that show the following: Life span shortens nonlinearly with increased temperature or added oxidant concentration, and life span increases in mutants having more chaperones or proteasomes. It predicts observed increases in cellular oxidative damage with age and provides a mechanism for the Gompertz-like rise in mortality observed in humans and other organisms. Overall, the model shows how the instability of proteins sets the rate at which damage accumulates with age and upends a cell’s normal proteostasis balance.
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4
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Papsdorf K, Sima S, Schmauder L, Peter S, Renner L, Hoffelner P, Richter K. head-bent resistant Hsc70 variants show reduced Hsp40 affinity and altered protein folding activity. Sci Rep 2019; 9:11955. [PMID: 31420580 PMCID: PMC6697693 DOI: 10.1038/s41598-019-48109-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 07/25/2019] [Indexed: 01/19/2023] Open
Abstract
The molecular chaperone Hsc70 performs essential tasks by folding proteins. Hsc70 is driven by the hydrolysis of ATP and tuned by the association with various co-chaperones. One such cofactor is the nematode nucleotide exchange factor UNC-23, whose mutation disrupts muscle attachment and induces a severe head-bent phenotype in C.elegans. Interestingly, four mutations in Hsc70 can suppress this phenotype, but the molecular mechanism underlying this suppression is unknown. Here we characterize these four suppressor variants, Hsc70 D233N, S321F, A379V and D384N. In vitro only Hsc70 S321F shows reduced stability and altered nucleotide interaction, but all mutations affect the ATPase stimulation. In particular, Hsc70 D233N and Hsc70 A379V show strongly reduced interactions with DNJ-12 and DNJ-13. Nucleotide exchange factor binding instead is barely influenced in Hsc70 D233N, A379V and D384N and their chaperone activity is preserved. Molecular dynamics simulations suggest that effects in Hsc70 S321F and Hsc70 A379V originate from steric clashes in the vicinity of the mutation site, while D233N disrupts a salt bridge that contributes to Hsc70’s nucleotide-induced conformational changes. In summary, the analyzed mutants show altered ATPase and refolding activity caused by changes in Hsp40 binding.
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Affiliation(s)
- Katharina Papsdorf
- Center for integrated protein research at the Department of Chemie, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany.,Stanford University School of Medicine, Department of Genetics, 300 Pasteur Drive, Stanford, CA, 94305, USA
| | - Siyuan Sima
- Center for integrated protein research at the Department of Chemie, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Lukas Schmauder
- Center for integrated protein research at the Department of Chemie, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Sebastian Peter
- Center for integrated protein research at the Department of Chemie, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Lisa Renner
- Center for integrated protein research at the Department of Chemie, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Patrica Hoffelner
- Center for integrated protein research at the Department of Chemie, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Klaus Richter
- Center for integrated protein research at the Department of Chemie, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany.
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5
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Shen K, Gamerdinger M, Chan R, Gense K, Martin EM, Sachs N, Knight PD, Schlömer R, Calabrese AN, Stewart KL, Leiendecker L, Baghel A, Radford SE, Frydman J, Deuerling E. Dual Role of Ribosome-Binding Domain of NAC as a Potent Suppressor of Protein Aggregation and Aging-Related Proteinopathies. Mol Cell 2019; 74:729-741.e7. [PMID: 30982745 PMCID: PMC6527867 DOI: 10.1016/j.molcel.2019.03.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 01/22/2019] [Accepted: 03/08/2019] [Indexed: 01/11/2023]
Abstract
The nascent polypeptide-associated complex (NAC) is a conserved ribosome-associated protein biogenesis factor. Whether NAC exerts chaperone activity and whether this function is restricted to de novo protein synthesis is unknown. Here, we demonstrate that NAC directly exerts chaperone activity toward structurally diverse model substrates including polyglutamine (PolyQ) proteins, firefly luciferase, and Aβ40. Strikingly, we identified the positively charged ribosome-binding domain in the N terminus of the βNAC subunit (N-βNAC) as a major chaperone entity of NAC. N-βNAC by itself suppressed aggregation of PolyQ-expanded proteins in vitro, and the positive charge of this domain was critical for this activity. Moreover, we found that NAC also exerts a ribosome-independent chaperone function in vivo. Consistently, we found that a substantial fraction of NAC is non-ribosomal bound in higher eukaryotes. In sum, NAC is a potent suppressor of aggregation and proteotoxicity of mutant PolyQ-expanded proteins associated with human diseases like Huntington's disease and spinocerebellar ataxias.
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Affiliation(s)
- Koning Shen
- Department of Biology, Stanford University, Stanford, CA 94305-5430, USA
| | | | - Rebecca Chan
- Department of Biology, Stanford University, Stanford, CA 94305-5430, USA
| | - Karina Gense
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Esther M Martin
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Nadine Sachs
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Patrick D Knight
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Renate Schlömer
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Katie L Stewart
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Lukas Leiendecker
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Ankit Baghel
- Department of Biology, Stanford University, Stanford, CA 94305-5430, USA
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
| | - Judith Frydman
- Department of Biology, Stanford University, Stanford, CA 94305-5430, USA.
| | - Elke Deuerling
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany.
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6
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Trcka F, Durech M, Vankova P, Chmelik J, Martinkova V, Hausner J, Kadek A, Marcoux J, Klumpler T, Vojtesek B, Muller P, Man P. Human Stress-inducible Hsp70 Has a High Propensity to Form ATP-dependent Antiparallel Dimers That Are Differentially Regulated by Cochaperone Binding. Mol Cell Proteomics 2019; 18:320-337. [PMID: 30459217 PMCID: PMC6356074 DOI: 10.1074/mcp.ra118.001044] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/09/2018] [Indexed: 12/23/2022] Open
Abstract
Eukaryotic protein homeostasis (proteostasis) is largely dependent on the action of highly conserved Hsp70 molecular chaperones. Recent evidence indicates that, apart from conserved molecular allostery, Hsp70 proteins have retained and adapted the ability to assemble as functionally relevant ATP-bound dimers throughout evolution. Here, we have compared the ATP-dependent dimerization of DnaK, human stress-inducible Hsp70, Hsc70 and BiP Hsp70 proteins, showing that their dimerization propensities differ, with stress-inducible Hsp70 being predominantly dimeric in the presence of ATP. Structural analyses using hydrogen/deuterium exchange mass spectrometry, native electrospray ionization mass spectrometry and small-angle X-ray scattering revealed that stress-inducible Hsp70 assembles in solution as an antiparallel dimer with the intermolecular interface closely resembling the ATP-bound dimer interfaces captured in DnaK and BiP crystal structures. ATP-dependent dimerization of stress-inducible Hsp70 is necessary for its efficient interaction with Hsp40, as shown by experiments with dimerization-deficient mutants. Moreover, dimerization of ATP-bound Hsp70 is required for its participation in high molecular weight protein complexes detected ex vivo, supporting its functional role in vivo As human cytosolic Hsp70 can interact with tetratricopeptide repeat (TPR) domain containing cochaperones, we tested the interaction of Hsp70 ATP-dependent dimers with Chip and Tomm34 cochaperones. Although Chip associates with intact Hsp70 dimers to form a larger complex, binding of Tomm34 disrupts the Hsp70 dimer and this event plays an important role in Hsp70 activity regulation. In summary, this study provides structural evidence of robust ATP-dependent antiparallel dimerization of human inducible Hsp70 protein and suggests a novel role of TPR domain cochaperones in multichaperone complexes involving Hsp70 ATP-bound dimers.
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Affiliation(s)
- Filip Trcka
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Michal Durech
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Pavla Vankova
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Josef Chmelik
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Veronika Martinkova
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Jiri Hausner
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Alan Kadek
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Julien Marcoux
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Tomas Klumpler
- CEITEC-Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Borivoj Vojtesek
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Petr Muller
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic;.
| | - Petr Man
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic;.
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7
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Tao C, Jin X, Zhu L, Li H. Two-Dimensional Gel Electrophoresis-Based Proteomic Analysis Reveals N-terminal Truncation of the Hsc70 Protein in Cotton Fibers In Vivo. Sci Rep 2016; 6:36961. [PMID: 27833127 PMCID: PMC5105075 DOI: 10.1038/srep36961] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 10/21/2016] [Indexed: 11/09/2022] Open
Abstract
On two-dimensional electrophoresis gels, six protein spots from cotton ovules and fibers were identified as heat shock cognate 70 kD protein (Hsc70). Three spots corresponded to an experimental molecular weight (MW) of 70 kD (spots 1, 2 and 3), and the remaining three spots corresponded to an experimental MW slightly greater than 45 kD (spots 4, 5 and 6). Protein spots 1, 2 and 3 were abundant on gels of 0-day (the day of anthesis) wild-type (WT) ovules, 0-day fuzzless-lintless mutant ovules and 10-day WT ovules but absent from gels of 10-day WT fibers. Three individual transcripts encoding these six protein spots were obtained by using rapid amplification of cDNA ends (RACE). Edman degradation and western blotting confirmed that the three 45 kD Hsc70 protein spots had the same N-terminal, which started from the T271 amino acid in the intact Hsc70 protein. Furthermore, quadrupole time-of-flight mass spectrometry analysis identified a methylation modification on the arginine at position 475 for protein spots 4 and 5. Our data demonstrate that site-specific in vivo N-terminal truncation of the Hsc70 protein was particularly prevalent in cotton fibers, indicating that post-translational regulation might play an important role in cotton fiber development.
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Affiliation(s)
- Chengcheng Tao
- College of Life Sciences, Key Laboratory of Agrobiotechnology, Shihezi University, Shihezi, 832003, China.,Institute of Tropical Biosciences and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
| | - Xiang Jin
- College of Life Sciences, Key Laboratory of Agrobiotechnology, Shihezi University, Shihezi, 832003, China.,Institute of Tropical Biosciences and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
| | - Liping Zhu
- College of Life Sciences, Key Laboratory of Agrobiotechnology, Shihezi University, Shihezi, 832003, China
| | - Hongbin Li
- College of Life Sciences, Key Laboratory of Agrobiotechnology, Shihezi University, Shihezi, 832003, China
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8
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Durech M, Trcka F, Man P, Blackburn EA, Hernychova L, Dvorakova P, Coufalova D, Kavan D, Vojtesek B, Muller P. Novel Entropically Driven Conformation-specific Interactions with Tomm34 Protein Modulate Hsp70 Protein Folding and ATPase Activities. Mol Cell Proteomics 2016; 15:1710-27. [PMID: 26944342 DOI: 10.1074/mcp.m116.058131] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Indexed: 12/18/2022] Open
Abstract
Co-chaperones containing tetratricopeptide repeat (TPR) domains enable cooperation between Hsp70 and Hsp90 to maintain cellular proteostasis. Although the details of the molecular interactions between some TPR domains and heat shock proteins are known, we describe a novel mechanism by which Tomm34 interacts with and coordinates Hsp70 activities. In contrast to the previously defined Hsp70/Hsp90-organizing protein (Hop), Tomm34 interaction is dependent on the Hsp70 chaperone cycle. Tomm34 binds Hsp70 in a complex process; anchorage of the Hsp70 C terminus by the TPR1 domain is accompanied by additional contacts formed exclusively in the ATP-bound state of Hsp70 resulting in a high affinity entropically driven interaction. Tomm34 induces structural changes in determinants within the Hsp70-lid subdomain and modulates Hsp70/Hsp40-mediated refolding and Hsp40-stimulated Hsp70 ATPase activity. Because Tomm34 recruits Hsp90 through its TPR2 domain, we propose a model in which Tomm34 enables Hsp70/Hsp90 scaffolding and influences the Hsp70 chaperone cycle, providing an additional role for co-chaperones that contain multiple TPR domains in regulating protein homeostasis.
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Affiliation(s)
- Michal Durech
- From the ‡Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty Kopec 7, 656 53 Brno, Czech Republic
| | - Filip Trcka
- From the ‡Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty Kopec 7, 656 53 Brno, Czech Republic
| | - Petr Man
- ¶Institute of Microbiology, The Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic; ‖Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Elizabeth A Blackburn
- **Centre for Translational and Chemical Biology, Institute of Structural and Molecular Biology, University of Edinburgh, Max Born Crescent, The King's Buildings, Edinburgh EH9 3JR, United Kingdom
| | - Lenka Hernychova
- From the ‡Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty Kopec 7, 656 53 Brno, Czech Republic
| | - Petra Dvorakova
- From the ‡Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty Kopec 7, 656 53 Brno, Czech Republic
| | - Dominika Coufalova
- From the ‡Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty Kopec 7, 656 53 Brno, Czech Republic
| | - Daniel Kavan
- ¶Institute of Microbiology, The Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic; ‖Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Borivoj Vojtesek
- From the ‡Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty Kopec 7, 656 53 Brno, Czech Republic;
| | - Petr Muller
- From the ‡Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty Kopec 7, 656 53 Brno, Czech Republic;
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9
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Selective activators of protein phosphatase 5 target the auto-inhibitory mechanism. Biosci Rep 2015; 35:BSR20150042. [PMID: 26182372 PMCID: PMC4721540 DOI: 10.1042/bsr20150042] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 03/06/2015] [Indexed: 12/18/2022] Open
Abstract
This paper describes the identification of compounds, which stimulate the activity of the protein phosphatase PPH-5 and addresses the influence of the identified compounds on the enzymatic properties and the potential mechanism of their action. Protein phosphatase 5 (PP5) is an evolutionary conserved serine/threonine phosphatase. Its dephosphorylation activity modulates a diverse set of cellular factors including protein kinases and the microtubule-associated tau protein involved in neurodegenerative disorders. It is auto-regulated by its heat-shock protein (Hsp90)-interacting tetratricopeptide repeat (TPR) domain and its C-terminal α-helix. In the present study, we report the identification of five specific PP5 activators [PP5 small-molecule activators (P5SAs)] that enhance the phosphatase activity up to 8-fold. The compounds are allosteric modulators accelerating efficiently the turnover rate of PP5, but do barely affect substrate binding or the interaction between PP5 and the chaperone Hsp90. Enzymatic studies imply that the compounds bind to the phosphatase domain of PP5. For the most promising compound crystallographic comparisons of the apo PP5 and the PP5–P5SA-2 complex indicate a relaxation of the auto-inhibited state of PP5. Residual electron density and mutation analyses in PP5 suggest activator binding to a pocket in the phosphatase/TPR domain interface, which may exert regulatory functions. These compounds thus may expose regulatory mechanisms in the PP5 enzyme and serve to develop optimized activators based on these scaffolds.
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10
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Protein folding, misfolding and quality control: the role of molecular chaperones. Essays Biochem 2014; 56:53-68. [DOI: 10.1042/bse0560053] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Cells have to cope with stressful conditions and adapt to changing environments. Heat stress, heavy metal ions or UV stress induce damage to cellular proteins and disturb the balanced status of the proteome. The adjusted balance between folded and folding proteins, called protein homoeostasis, is required for every aspect of cellular functionality. Protective proteins called chaperones are expressed under extreme conditions in order to prevent aggregation of cellular proteins and safeguard protein quality. These chaperones co-operate during de novo folding, refolding and disaggregation of damaged proteins and in many cases refold them to their functional state. Even under physiological conditions these machines support protein homoeostasis and maintain the balance between de novo folding and degradation. Mutations generating unstable proteins, which are observed in numerous human diseases such as Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis and cystic fibrosis, also challenge the protein quality control system. A better knowledge of how the protein homoeostasis system is regulated will lead to an improved understanding of these diseases and provide potential targets for therapy.
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11
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Papsdorf K, Sacherl J, Richter K. The balanced regulation of Hsc70 by DNJ-13 and UNC-23 is required for muscle functionality. J Biol Chem 2014; 289:25250-61. [PMID: 25053410 DOI: 10.1074/jbc.m114.565234] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molecular chaperone Hsc70 assists in the folding of non-native proteins together with its J domain- and BAG domain-containing cofactors. In Caenorhabditis elegans, two BAG domain-containing proteins can be identified, one of them being UNC-23, whose mutation induces severe motility dysfunctions. Using reporter strains, we find that the full-length UNC-23, in contrast to C-terminal fragments, localizes specifically to the muscular attachment sites. C-terminal fragments of UNC-23 instead perform all Hsc70-related functions, like ATPase stimulation and regulation of folding activity, albeit with lower affinity than BAG-1. Interestingly, overexpression of CFP-Hsc70 can induce muscular defects in wild-type nematodes that phenocopy the knockout of its cofactor UNC-23. Strikingly, the motility dysfunction in the unc-23 mutated strain can be cured specifically by down-regulation of the antagonistic Hsc70 cochaperone DNJ-13, implying that the severe phenotype is caused by misregulation of the Hsc70 cycle. These findings point out that the balanced action of cofactors in the ATP-driven cycle of Hsc70 is crucial for the contribution of Hsc70 to muscle functionality.
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Affiliation(s)
- Katharina Papsdorf
- From the Department of Biotechnology and Center for Integrated Protein Science Munich (CIPS), Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Julia Sacherl
- From the Department of Biotechnology and Center for Integrated Protein Science Munich (CIPS), Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Klaus Richter
- From the Department of Biotechnology and Center for Integrated Protein Science Munich (CIPS), Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
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12
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Eckl JM, Drazic A, Rutz DA, Richter K. Nematode Sgt1-homologue D1054.3 binds open and closed conformations of Hsp90 via distinct binding sites. Biochemistry 2014; 53:2505-14. [PMID: 24660900 DOI: 10.1021/bi5000542] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heat shock protein 90 (Hsp90) is a highly conserved ATP-driven machine involved in client protein maturation, folding, and activation. The chaperone is supported by a set of cochaperones that confer client specificities. One of those proteins is the suppressor of G2 allele of skp1 (Sgt1), which participates together with Hsp90 in the immune responses of plants. Sgt1 consists of three domains: a TPR-, CS-, and SGS-domain, conserved in plants, yeast, and humans. The TPR-domain though is lacking in nematodes and insects. We observe that the Caenorhabditis elegans Sgt1 homologue D1054.3 binds to Hsp90 in the absence of nucleotides but much stronger in the presence of ATP and ATPγS. The latter binding mode is similar to p23, another CS-domain containing Hsp90 cofactor, even though binding is not observable for p23 in the absence of nucleotides. We use point mutations in Hsp90, which accumulate different conformations in the ATPase cycle, to differentiate between binding to open and closed Hsp90 conformations. These data support a strong contribution of the Hsp90 conformation to Sgt1 binding and highlight the ability of this cofactor to interact with all known Hsp90 conformations albeit with different affinities.
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Affiliation(s)
- Julia M Eckl
- Department of Chemistry, Technische Universität München , 85748 Garching, Germany
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Battenberg OA, Yang Y, Verhelst SHL, Sieber SA. Target profiling of 4-hydroxyderricin in S. aureus reveals seryl-tRNA synthetase binding and inhibition by covalent modification. MOLECULAR BIOSYSTEMS 2013; 9:343-51. [DOI: 10.1039/c2mb25446h] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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