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Lee J, Ryu B, Kim T, Kim KK. Cryo-EM structure of a 16.5-kDa small heat-shock protein from Methanocaldococcus jannaschii. Int J Biol Macromol 2024; 258:128763. [PMID: 38103675 DOI: 10.1016/j.ijbiomac.2023.128763] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/07/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023]
Abstract
The small heat-shock protein (sHSP) from the archaea Methanocaldococcus jannaschii, MjsHSP16.5, functions as a broad substrate ATP-independent holding chaperone protecting misfolded proteins from aggregation under stress conditions. This protein is the first sHSP characterized by X-ray crystallography, thereby contributing significantly to our understanding of sHSPs. However, despite numerous studies assessing its functions and structures, the precise arrangement of the N-terminal domains (NTDs) within this sHSP cage remains elusive. Here we present the cryo-electron microscopy (cryo-EM) structure of MjsHSP16.5 at 2.49-Å resolution. The subunits of MjsHSP16.5 in the cryo-EM structure exhibit lesser compaction compared to their counterparts in the crystal structure. This structural feature holds particular significance in relation to the biophysical properties of MjsHSP16.5, suggesting a close resemblance to this sHSP native state. Additionally, our cryo-EM structure unveils the density of residues 24-33 within the NTD of MjsHSP16.5, a feature that typically remains invisible in the majority of its crystal structures. Notably, these residues show a propensity to adopt a β-strand conformation and engage in antiparallel interactions with strand β1, both intra- and inter-subunit modes. These structural insights are corroborated by structural predictions, disulfide bond cross-linking studies of Cys-substitution mutants, and protein disaggregation assays. A comprehensive understanding of the structural features of MjsHSP16.5 expectedly holds the potential to inspire a wide range of interdisciplinary applications, owing to the renowned versatility of this sHSP as a nanoscale protein platform.
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Affiliation(s)
- Joohyun Lee
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Bumhan Ryu
- Research Solution Center, Institute for Basic Science (IBS), Daejeon 34126, Republic of Korea
| | - Truc Kim
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea.
| | - Kyeong Kyu Kim
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea.
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Alderson TR, Ying J, Bax A, Benesch JLP, Baldwin AJ. Conditional Disorder in Small Heat-shock Proteins. J Mol Biol 2020; 432:3033-3049. [PMID: 32081587 PMCID: PMC7245567 DOI: 10.1016/j.jmb.2020.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [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: 10/30/2019] [Revised: 01/27/2020] [Accepted: 02/09/2020] [Indexed: 12/31/2022]
Abstract
Small heat-shock proteins (sHSPs) are molecular chaperones that respond to cellular stresses to combat protein aggregation. HSP27 is a critical human sHSP that forms large, dynamic oligomers whose quaternary structures and chaperone activities depend on environmental factors. Upon exposure to cellular stresses, such as heat shock or acidosis, HSP27 oligomers can dissociate into dimers and monomers, which leads to significantly enhanced chaperone activity. The structured core of the protein, the α-crystallin domain (ACD), forms dimers and can prevent the aggregation of substrate proteins to a similar degree as the full-length protein. When the ACD dimer dissociates into monomers, it partially unfolds and exhibits enhanced activity. Here, we used solution-state NMR spectroscopy to characterize the structure and dynamics of the HSP27 ACD monomer. Web show that the monomer is stabilized at low pH and that its backbone chemical shifts, 15N relaxation rates, and 1H-15N residual dipolar couplings suggest structural changes and rapid motions in the region responsible for dimerization. By analyzing the solvent accessible and buried surface areas of sHSP structures in the context of a database of dimers that are known to dissociate into disordered monomers, we predict that ACD dimers from sHSPs across all kingdoms of life may partially unfold upon dissociation. We propose a general model in which conditional disorder-the partial unfolding of ACDs upon monomerization-is a common mechanism for sHSP activity.
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Affiliation(s)
- T Reid Alderson
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK; Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jinfa Ying
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Justin L P Benesch
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK.
| | - Andrew J Baldwin
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK.
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Jovcevski B, Andrew Aquilina J, Benesch JLP, Ecroyd H. The influence of the N-terminal region proximal to the core domain on the assembly and chaperone activity of αB-crystallin. Cell Stress Chaperones 2018; 23:827-836. [PMID: 29520626 PMCID: PMC6111084 DOI: 10.1007/s12192-018-0889-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [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: 01/18/2018] [Revised: 02/19/2018] [Accepted: 02/24/2018] [Indexed: 01/24/2023] Open
Abstract
αB-Crystallin (HSPB5) is a small heat-shock protein that is composed of dimers that then assemble into a polydisperse ensemble of oligomers. Oligomerisation is mediated by heterologous interactions between the C-terminal tail of one dimer and the core "α-crystallin" domain of another and stabilised by interactions made by the N-terminal region. Comparatively little is known about the latter contribution, but previous studies have suggested that residues in the region 54-60 form contacts that stabilise the assembly. We have generated mutations in this region (P58A, S59A, S59K, R56S/S59R and an inversion of residues 54-60) to examine their impact on oligomerisation and chaperone activity in vitro. By using native mass spectrometry, we found that all the αB-crystallin mutants were assembly competent, populating similar oligomeric distributions to wild-type, ranging from 16-mers to 30-mers. However, circular dichroism spectroscopy, intrinsic tryptophan and bis-ANS fluorescence studies demonstrated that the secondary structure differs to wild type, the 54-60 inversion mutation having the greatest impact. All the mutants exhibited a dramatic decrease in exposed hydrophobicity. We also found that the mutants in general were equally active as the wild-type protein in inhibiting the amorphous aggregation of insulin and seeded amyloid fibrillation of α-synuclein in vitro, except for the 54-60 inversion mutant, which was significantly less effective at inhibiting insulin aggregation. Our data indicate that alterations in the part of the N-terminal region proximal to the core domain do not drastically affect the oligomerisation of αB-crystallin, reinforcing the robustness of αB-crystallin in functioning as a molecular chaperone.
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Affiliation(s)
- Blagojce Jovcevski
- Illawarra Health and Medical Research Institute and School of Biological Sciences, University of Wollongong, Northfields Ave, Wollongong, NSW, 2522, Australia
| | - J Andrew Aquilina
- Illawarra Health and Medical Research Institute and School of Biological Sciences, University of Wollongong, Northfields Ave, Wollongong, NSW, 2522, Australia
| | - Justin L P Benesch
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK
| | - Heath Ecroyd
- Illawarra Health and Medical Research Institute and School of Biological Sciences, University of Wollongong, Northfields Ave, Wollongong, NSW, 2522, Australia.
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Marklund EG, Zhang Y, Basha E, Benesch JLP, Vierling E. Structural and functional aspects of the interaction partners of the small heat-shock protein in Synechocystis. Cell Stress Chaperones 2018; 23:723-732. [PMID: 29476342 PMCID: PMC6045555 DOI: 10.1007/s12192-018-0884-3] [Citation(s) in RCA: 4] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 01/09/2018] [Accepted: 02/01/2018] [Indexed: 01/28/2023] Open
Abstract
The canonical function of small heat-shock proteins (sHSPs) is to interact with proteins destabilized under conditions of cellular stress. While the breadth of interactions made by many sHSPs is well-known, there is currently little knowledge about what structural features of the interactors form the basis for their recognition. Here, we have identified 83 in vivo interactors of the sole sHSP in the cyanobacterium Synechocystis sp. PCC 6803, HSP16.6, reflective of stable associations with soluble proteins made under heat-shock conditions. By performing bioinformatic analyses on these interactors, we identify primary and secondary structural elements that are enriched relative to expectations from the cyanobacterial genome. In addition, by examining the Synechocystis interactors and comparing them with those identified to bind sHSPs in other prokaryotes, we show that sHSPs associate with specific proteins and biological processes. Our data are therefore consistent with a picture of sHSPs being broadly specific molecular chaperones that act to protect multiple cellular pathways.
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Affiliation(s)
- Erik G Marklund
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK
- Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala, 75123, Sweden
| | - Yichen Zhang
- Department of Biochemistry & Molecular Biology, University of Massachusetts, Amherst, MA, 01003, USA
- Alorica, Inc., Irvine, CA, USA
| | - Eman Basha
- Department of Biochemistry & Molecular Biology, University of Massachusetts, Amherst, MA, 01003, USA
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Justin L P Benesch
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK.
| | - Elizabeth Vierling
- Department of Biochemistry & Molecular Biology, University of Massachusetts, Amherst, MA, 01003, USA.
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Diokmetzidou A, Soumaka E, Kloukina I, Tsikitis M, Makridakis M, Varela A, Davos CH, Georgopoulos S, Anesti V, Vlahou A, Capetanaki Y. Desmin and αB-crystallin interplay in the maintenance of mitochondrial homeostasis and cardiomyocyte survival. J Cell Sci 2016; 129:3705-3720. [PMID: 27566162 DOI: 10.1242/jcs.192203] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [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: 05/09/2016] [Accepted: 08/15/2016] [Indexed: 12/20/2022] Open
Abstract
The association of desmin with the α-crystallin Β-chain (αΒ-crystallin; encoded by CRYAB), and the fact that mutations in either one of them leads to heart failure in humans and mice, suggests a potential compensatory interplay between the two in cardioprotection. To address this hypothesis, we investigated the consequences of αΒ-crystallin overexpression in the desmin-deficient (Des-/-) mouse model, which possesses a combination of the pathologies found in most cardiomyopathies, with mitochondrial defects as a hallmark. We demonstrated that cardiac-specific αΒ-crystallin overexpression ameliorates all these defects and improves cardiac function to almost wild-type levels. Protection by αΒ-crystallin overexpression is linked to maintenance of proper mitochondrial protein levels, inhibition of abnormal mitochondrial permeability transition pore activation and maintenance of mitochondrial membrane potential (Δψm). Furthermore, we found that both desmin and αΒ-crystallin are localized at sarcoplasmic reticulum (SR)-mitochondria-associated membranes (MAMs), where they interact with VDAC, Mic60 - the core component of mitochondrial contact site and cristae organizing system (MICOS) complex - and ATP synthase, suggesting that these associations could be crucial in mitoprotection at different levels.
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Affiliation(s)
- Antigoni Diokmetzidou
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Elisavet Soumaka
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Ismini Kloukina
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Mary Tsikitis
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Manousos Makridakis
- Center of Systems Biology, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Aimilia Varela
- Center of Clinical, Experimental Surgery & Translational Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Constantinos H Davos
- Center of Clinical, Experimental Surgery & Translational Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Spiros Georgopoulos
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Vasiliki Anesti
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Antonia Vlahou
- Center of Systems Biology, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - Yassemi Capetanaki
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
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Ray NJ, Hall D, Carver JA. Deamidation of N76 in human γS-crystallin promotes dimer formation. Biochim Biophys Acta Gen Subj 2015; 1860:315-24. [PMID: 26318015 DOI: 10.1016/j.bbagen.2015.08.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [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: 04/17/2015] [Revised: 06/28/2015] [Accepted: 08/24/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Cataract formation is often attributed to the build-up of post-translational modifications in the crystallin proteins of the eye lens. One such modification, the deamidation of N76 in human γS-crystallin to D76, is highly correlated with age-related cataract (Hooi et al. Invest. Ophthalmol. Vis. Sci. 53 (2012) 3554-3561). In the current work, this modification has been extensively characterised in vitro. METHODS Biophysical characterisation was performed on wild type and N76D γS-crystallins using turbidity measurements to monitor aggregation, intrinsic fluorescence and circular dichroism spectroscopy to determine the folded state and NMR spectroscopy for identifying local changes in structure. Protein mass was determined using SEC-MALLS and analytical ultracentrifugation methods. RESULTS Relative to the wild type protein, deamidation at N76 in γS-crystallin causes an increase in the thermal stability and resistance to thermally induced aggregation alongside a decrease in stability to denaturants, a propensity to aggregate rapidly once destabilised and a tendency to form a dimer. We ascribe the apparent increase in thermal stability upon deamidation to the formation of dimer which prevents the unfolding of the inherently less stable monomer. CONCLUSIONS Deamidation causes a decrease in stability of γS-crystallin but this is offset by an increased tendency for dimer formation. GENERAL SIGNIFICANCE Deamidation at N76 in human γS-crystallin likely has a combinatorial effect with other post-translational crystallin modifications to induce age-related cataract. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
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Affiliation(s)
- Nicholas J Ray
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Damien Hall
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - John A Carver
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia.
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