1
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Moritz MNO, Dores-Silva PR, Coto ALS, Selistre-de-Araújo HS, Leitão A, Cauvi DM, De Maio A, Carra S, Borges JC. Human HSP70-escort protein 1 (hHep1) interacts with negatively charged lipid bilayers and cell membranes. Cell Stress Chaperones 2023; 28:1001-1012. [PMID: 38001371 PMCID: PMC10746634 DOI: 10.1007/s12192-023-01394-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 11/09/2023] [Accepted: 11/10/2023] [Indexed: 11/26/2023] Open
Abstract
Human Hsp70-escort protein 1 (hHep1) is a cochaperone that assists in the function and stability of mitochondrial HSPA9. Similar to HSPA9, hHep1 is located outside the mitochondria and can interact with liposomes. In this study, we further investigated the structural and thermodynamic behavior of interactions between hHep1 and negatively charged liposomes, as well as interactions with cellular membranes. Our results showed that hHep1 interacts peripherally with liposomes formed by phosphatidylserine and cardiolipin and remains partially structured, exhibiting similar affinities for both. In addition, after being added to the cell membrane, recombinant hHep1 was incorporated by cells in a dose-dependent manner. Interestingly, the association of HSPA9 with hHep1 improved the incorporation of these proteins into the lipid bilayer. These results demonstrated that hHep1 can interact with lipids also present in the plasma membrane, indicating roles for this cochaperone outside of mitochondria.
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Affiliation(s)
- Milene N O Moritz
- São Carlos Institute of Chemistry, University of São Paulo - USP, P.O. Box 780, São Carlos, SP, 13560-970, Brazil
| | - Paulo R Dores-Silva
- São Carlos Institute of Chemistry, University of São Paulo - USP, P.O. Box 780, São Carlos, SP, 13560-970, Brazil
- Division of Trauma, Critical Care, Burns and Acute Care Surgery, Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Amanda L S Coto
- São Carlos Institute of Chemistry, University of São Paulo - USP, P.O. Box 780, São Carlos, SP, 13560-970, Brazil
| | | | - Andrei Leitão
- São Carlos Institute of Chemistry, University of São Paulo - USP, P.O. Box 780, São Carlos, SP, 13560-970, Brazil
| | - David M Cauvi
- Division of Trauma, Critical Care, Burns and Acute Care Surgery, Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Antonio De Maio
- Division of Trauma, Critical Care, Burns and Acute Care Surgery, Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Serena Carra
- Centre for Neuroscience and Nanotechnology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Júlio Cesar Borges
- São Carlos Institute of Chemistry, University of São Paulo - USP, P.O. Box 780, São Carlos, SP, 13560-970, Brazil.
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2
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Li K, Zhai L, Fu S, Wu T, Zhang X, Xu X, Han Z, Wang Y. Genome-wide analysis of the MdZR gene family revealed MdZR2.2-induced salt and drought stress tolerance in apple rootstock. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2023:111755. [PMID: 37290593 DOI: 10.1016/j.plantsci.2023.111755] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/30/2023] [Accepted: 06/05/2023] [Indexed: 06/10/2023]
Abstract
The DNL-type zinc finger protein constitutes a zinc ribbon protein (ZR) family, which belongs to a branch of zinc finger protein and plays an essential role in response to abiotic stress. Here, we identified six apple (Malus domestica) MdZR genes. Based on their phylogenetic relationship and gene structure, the MdZR genes were divided into three categories, including MdZR1, MdZR2, and MdZR3. Subcellular results showed that the MdZRs are located on the nuclear and membrane. The transcriptome data showed that MdZR2.2 is expressed in various tissues. The expression analysis results showed that MdZR2.2 was significantly upregulated under salt and drought treatments. Thus, we selected MdZR2.2 for further research. Overexpression of MdZR2.2 in apple callus improved their tolerance to drought and salt stress and ability to scavenge reactive oxygen species (ROS). In contrast, transgenic apple roots with silenced MdZR2.2 grew more poorly than the wild type when subjected to salt and drought stress, which reduced their ability to scavenge ROS. To our knowledge, this is the first study to analyze the MdZR protein family. This study identified a gene that responds to drought and salt stress. Our findings lay a foundation for a comprehensive analysis of the MdZR family members.
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Affiliation(s)
- Keting Li
- College of Horticulture, China Agricultural University, Beijing 100193, P.R. China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology), Ministry of Agriculture and Rural Affairs, Beijing 100193, P.R. China
| | - Longmei Zhai
- College of Horticulture, China Agricultural University, Beijing 100193, P.R. China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology), Ministry of Agriculture and Rural Affairs, Beijing 100193, P.R. China
| | - Sitong Fu
- College of Horticulture, China Agricultural University, Beijing 100193, P.R. China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology), Ministry of Agriculture and Rural Affairs, Beijing 100193, P.R. China
| | - Ting Wu
- College of Horticulture, China Agricultural University, Beijing 100193, P.R. China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology), Ministry of Agriculture and Rural Affairs, Beijing 100193, P.R. China
| | - Xinzhong Zhang
- College of Horticulture, China Agricultural University, Beijing 100193, P.R. China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology), Ministry of Agriculture and Rural Affairs, Beijing 100193, P.R. China
| | - Xuefeng Xu
- College of Horticulture, China Agricultural University, Beijing 100193, P.R. China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology), Ministry of Agriculture and Rural Affairs, Beijing 100193, P.R. China
| | - Zhenhai Han
- College of Horticulture, China Agricultural University, Beijing 100193, P.R. China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology), Ministry of Agriculture and Rural Affairs, Beijing 100193, P.R. China
| | - Yi Wang
- College of Horticulture, China Agricultural University, Beijing 100193, P.R. China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology), Ministry of Agriculture and Rural Affairs, Beijing 100193, P.R. China.
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3
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Esfahanian N, Knoblich CD, Bowman GA, Rezvani K. Mortalin: Protein partners, biological impacts, pathological roles, and therapeutic opportunities. Front Cell Dev Biol 2023; 11:1028519. [PMID: 36819105 PMCID: PMC9932541 DOI: 10.3389/fcell.2023.1028519] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
Mortalin (GRP75, HSPA9A), a heat shock protein (HSP), regulates a wide range of cellular processes, including cell survival, growth, and metabolism. The regulatory functions of mortalin are mediated through a diverse set of protein partners associated with different cellular compartments, which allows mortalin to perform critical functions under physiological conditions, including mitochondrial protein quality control. However, alteration of mortalin's activities, its abnormal subcellular compartmentalization, and its protein partners turn mortalin into a disease-driving protein in different pathological conditions, including cancers. Here, mortalin's contributions to tumorigenic pathways are explained. Pathology information based on mortalin's RNA expression extracted from The Cancer Genome Atlas (TCGA) transcriptomic database indicates that mortalin has an independent prognostic value in common tumors, including lung, breast, and colorectal cancer (CRC). Subsequently, the binding partners of mortalin reported in different cellular models, from yeast to mammalian cells, and its regulation by post-translational modifications are discussed. Finally, we focus on colorectal cancer and discuss how mortalin and its tumorigenic downstream protein targets are regulated by a ubiquitin-like protein through the 26S proteasomal degradation machinery. A broader understanding of the function of mortalin and its positive and negative regulation in the formation and progression of human diseases, particularly cancer, is essential for developing new strategies to treat a diverse set of human diseases critically associated with dysregulated mortalin.
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4
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Gill-Hille M, Wang A, Murcha MW. Presequence translocase-associated motor subunits of the mitochondrial protein import apparatus are dual-targeted to mitochondria and plastids. FRONTIERS IN PLANT SCIENCE 2022; 13:981552. [PMID: 36438081 PMCID: PMC9695410 DOI: 10.3389/fpls.2022.981552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 10/19/2022] [Indexed: 06/16/2023]
Abstract
The import and assembly of most of the mitochondrial proteome is regulated by protein translocases located within the mitochondrial membranes. The Presequence Translocase-Associated Motor (PAM) complex powers the translocation of proteins across the inner membrane and consists of Hsp70, the J-domain containing co-chaperones, Pam16 and Pam18, and their associated proteins Tim15 and Mge1. In Arabidopsis, multiple orthologues of Pam16, Pam18, Tim15 and Mge1 have been identified and a mitochondrial localization has been confirmed for most. As the localization of Pam18-1 has yet to be determined and a plastid localization has been observed for homologues of Tim15 and Mge1, we carried out a comprehensive targeting analysis of all PAM complex orthologues using multiple in vitro and in vivo methods. We found that, Pam16 was exclusively targeted to the mitochondria, but Pam18 orthologues could be targeted to both the mitochondria and plastids, as observed for the PAM complex interacting partner proteins Tim15 and Mge1.
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Affiliation(s)
- Mabel Gill-Hille
- School of Molecular Sciences, The University of Western Australia, Perth, WA, Australia
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, Australia
| | - Andre Wang
- School of Molecular Sciences, The University of Western Australia, Perth, WA, Australia
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, Australia
| | - Monika W. Murcha
- School of Molecular Sciences, The University of Western Australia, Perth, WA, Australia
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, Australia
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5
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Dores-Silva PR, Kiraly VTR, Moritz MNDO, Serrão VHB, Dos Passos PMS, Spagnol V, Teixeira FR, Gava LM, Cauvi DM, Ramos CHI, De Maio A, Borges JC. New insights on human Hsp70-escort protein 1: Chaperone activity, interaction with liposomes, cellular localizations and HSPA's self-assemblies remodeling. Int J Biol Macromol 2021; 182:772-784. [PMID: 33857516 DOI: 10.1016/j.ijbiomac.2021.04.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 04/09/2021] [Accepted: 04/09/2021] [Indexed: 11/24/2022]
Abstract
The 70 kDa heat shock proteins (Hsp70) are prone to self-assembly under thermal stress conditions, forming supramolecular assemblies (SMA), what may have detrimental consequences for cellular viability. In mitochondria, the cochaperone Hsp70-escort protein 1 (Hep1) maintains mitochondrial Hsp70 (mtHsp70) in a soluble and functional state, contributing to preserving proteostasis. Here we investigated the interaction between human Hep1 (hHep1) and HSPA9 (human mtHsp70) or HSPA1A (Hsp70-1A) in monomeric and thermic SMA states to unveil further information about the involved mechanisms. hHep1 was capable of blocking the formation of HSPA SMAs under a thermic treatment and stimulated HSPA ATPase activity in both monomeric and preformed SMA. The interaction of hHep1 with both monomeric and SMA HSPAs displayed a stoichiometric ratio close to 1, suggesting that hHep1 has access to most protomers within the SMA. Interestingly, hHep1 remodeled HSPA9 and HSPA1A SMAs into smaller forms. Furthermore, hHep1 was detected in the mitochondria and nucleus of cells transfected with the respective coding DNA and interacted with liposomes resembling mitochondrial membranes. Altogether, these new features reinforce that hHep1 act as a "chaperone for a chaperone", which may play a critical role in cellular proteostasis.
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Affiliation(s)
- Paulo Roberto Dores-Silva
- Sao Carlos Institute of Chemistry, University of Sao Paulo, Sao Carlos, SP, Brazil; Department of Surgery, School of Medicine, University of California, San Diego, La Jolla, USA
| | | | | | | | | | - Valentine Spagnol
- Department of Genetics and Evolution, Federal University of Sao Carlos, SP, Brazil
| | | | | | - David Mario Cauvi
- Department of Surgery, School of Medicine, University of California, San Diego, La Jolla, USA
| | | | - Antonio De Maio
- Department of Surgery, School of Medicine, University of California, San Diego, La Jolla, USA; Center for Investigations of Health and Education Disparities, University of California, San Diego, La Jolla, USA; Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, USA
| | - Júlio César Borges
- Sao Carlos Institute of Chemistry, University of Sao Paulo, Sao Carlos, SP, Brazil.
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6
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How to get to the other side of the mitochondrial inner membrane – the protein import motor. Biol Chem 2020; 401:723-736. [DOI: 10.1515/hsz-2020-0106] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/25/2020] [Indexed: 12/13/2022]
Abstract
AbstractBiogenesis of mitochondria relies on import of more than 1000 different proteins from the cytosol. Approximately 70% of these proteins follow the presequence pathway – they are synthesized with cleavable N-terminal extensions called presequences and reach the final place of their function within the organelle with the help of the TOM and TIM23 complexes in the outer and inner membranes, respectively. The translocation of proteins along the presequence pathway is powered by the import motor of the TIM23 complex. The import motor of the TIM23 complex is localized at the matrix face of the inner membrane and is likely the most complicated Hsp70-based system identified to date. How it converts the energy of ATP hydrolysis into unidirectional translocation of proteins into mitochondria remains one of the biggest mysteries of this translocation pathway. Here, the knowns and the unknowns of the mitochondrial protein import motor are discussed.
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7
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Moseng MA, Nix JC, Page RC. Biophysical Consequences of EVEN-PLUS Syndrome Mutations for the Function of Mortalin. J Phys Chem B 2019; 123:3383-3396. [PMID: 30933555 DOI: 10.1021/acs.jpcb.9b00071] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
HSPA9, the gene coding for the mitochondrial chaperone mortalin, is involved in various cellular roles such as mitochondrial protein import, folding, degradation, Fe-S cluster biogenesis, mitochondrial homeostasis, and regulation of the antiapoptotic protein p53. Mutations in the HSPA9 gene, particularly within the region coding for the nucleotide-binding domain (NBD), cause the autosomal disorder known as EVEN-PLUS syndrome. The resulting mutants R126W and Y128C are located on the surface of the mortalin-NBD near the binding interface with the interdomain linker (IDL). We used differential scanning fluorimetry (DSF), biolayer interferometry, X-ray crystallography, ATP hydrolysis assays, and Rosetta docking simulations to study the structural and functional consequences of the EVEN-PLUS syndrome-associated R126W and Y128C mutations within the mortalin-NBD. These results indicate that the surface mutations R126W and Y128C have far-reaching effects that disrupt ATP hydrolysis, interdomain linker binding, and thermostability and increase the propensity for aggregation. The structural differences observed provide insight into how the conformations of mortalin differ from other heat shock protein 70 (Hsp70) homologues. Combined, our biophysical and structural studies contribute to the understanding of the molecular basis for how disease-associated mortalin mutations affect mortalin functionality and the pathogenesis of EVEN-PLUS syndrome.
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Affiliation(s)
- Mitchell A Moseng
- Department of Chemistry and Biochemistry , Miami University , Oxford , Ohio 45056 , United States
| | - Jay C Nix
- Molecular Biology Consortium, Beamline 4.2.2, Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Richard C Page
- Department of Chemistry and Biochemistry , Miami University , Oxford , Ohio 45056 , United States
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8
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Nyakundi DO, Bentley SJ, Boshoff A. Hsp70 Escort Protein: More Than a Regulator of Mitochondrial Hsp70. CURR PROTEOMICS 2018. [DOI: 10.2174/1570164615666180713104919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Hsp70 members occupy a central role in proteostasis and are found in different eukaryotic
cellular compartments. The mitochondrial Hsp70/J-protein machinery performs multiple functions vital
for the proper functioning of the mitochondria, including forming part of the import motor that
transports proteins from the cytosol into the matrix and inner membrane, and subsequently folds these
proteins in the mitochondria. However, unlike other Hsp70s, mitochondrial Hsp70 (mtHsp70) has the
propensity to self-aggregate, accumulating as insoluble aggregates. The self-aggregation of mtHsp70 is
caused by both interdomain and intramolecular communication within the ATPase and linker domains.
Since mtHsp70 is unable to fold itself into an active conformation, it requires an Hsp70 escort protein
(Hep) to both inhibit self-aggregation and promote the correct folding. Hep1 orthologues are present in
the mitochondria of many eukaryotic cells but are absent in prokaryotes. Hep1 proteins are relatively
small and contain a highly conserved zinc-finger domain with one tetracysteine motif that is essential
for binding zinc ions and maintaining the function and solubility of the protein. The zinc-finger domain
lies towards the C-terminus of Hep1 proteins, with very little conservation outside of this domain.
Other than maintaining mtHsp70 in a functional state, Hep1 proteins play a variety of other roles in the
cell and have been proposed to function as both chaperones and co-chaperones. The cellular
localisation and some of the functions are often speculative and are not common to all Hep1 proteins
analysed to date.
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Affiliation(s)
- David O. Nyakundi
- Biotechnology Innovation Centre, Rhodes University, Grahamstown 6140, South Africa
| | - Stephen J. Bentley
- Biotechnology Innovation Centre, Rhodes University, Grahamstown 6140, South Africa
| | - Aileen Boshoff
- Biotechnology Innovation Centre, Rhodes University, Grahamstown 6140, South Africa
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9
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Plant mitochondrial protein import: the ins and outs. Biochem J 2018; 475:2191-2208. [PMID: 30018142 DOI: 10.1042/bcj20170521] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 06/19/2018] [Accepted: 06/21/2018] [Indexed: 01/29/2023]
Abstract
The majority of the mitochondrial proteome, required to fulfil its diverse range of functions, is cytosolically synthesised and translocated via specialised machinery. The dedicated translocases, receptors, and associated proteins have been characterised in great detail in yeast over the last several decades, yet many of the mechanisms that regulate these processes in higher eukaryotes are still unknown. In this review, we highlight the current knowledge of mitochondrial protein import in plants. Despite the fact that the mechanisms of mitochondrial protein import have remained conserved across species, many unique features have arisen in plants to encompass the developmental, tissue-specific, and stress-responsive regulation in planta. An understanding of unique features and mechanisms in plants provides us with a unique insight into the regulation of mitochondrial biogenesis in higher eukaryotes.
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10
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Nyakundi DO, Vuko LAM, Bentley SJ, Hoppe H, Blatch GL, Boshoff A. Plasmodium falciparum Hep1 Is Required to Prevent the Self Aggregation of PfHsp70-3. PLoS One 2016; 11:e0156446. [PMID: 27253881 PMCID: PMC4890766 DOI: 10.1371/journal.pone.0156446] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/14/2016] [Indexed: 11/29/2022] Open
Abstract
The majority of mitochondrial proteins are encoded in the nucleus and need to be imported from the cytosol into the mitochondria, and molecular chaperones play a key role in the efficient translocation and proper folding of these proteins in the matrix. One such molecular chaperone is the eukaryotic mitochondrial heat shock protein 70 (Hsp70); however, it is prone to self-aggregation and requires the presence of an essential zinc-finger protein, Hsp70-escort protein 1 (Hep1), to maintain its structure and function. PfHsp70-3, the only Hsp70 predicted to localize in the mitochondria of P. falciparum, may also rely on a Hep1 orthologue to prevent self-aggregation. In this study, we identified a putative Hep1 orthologue in P. falciparum and co-expression of PfHsp70-3 and PfHep1 enhanced the solubility of PfHsp70-3. PfHep1 suppressed the thermally induced aggregation of PfHsp70-3 but not the aggregation of malate dehydrogenase or citrate synthase, thus showing specificity for PfHsp70-3. Zinc ions were indeed essential for maintaining the function of PfHep1, as EDTA chelation abrogated its abilities to suppress the aggregation of PfHsp70-3. Soluble and functional PfHsp70-3, acquired by co-expression with PfHep-1, will facilitate the biochemical characterisation of this particular Hsp70 protein and its evaluation as a drug target for the treatment of malaria.
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Affiliation(s)
- David O. Nyakundi
- Biotechnology Innovation Centre, Rhodes University, Grahamstown 6140, South Africa
| | - Loyiso A. M. Vuko
- Biotechnology Innovation Centre, Rhodes University, Grahamstown 6140, South Africa
| | - Stephen J. Bentley
- Biotechnology Innovation Centre, Rhodes University, Grahamstown 6140, South Africa
| | - Heinrich Hoppe
- Department of Biochemistry and Microbiology, Rhodes University, Grahamstown 6140, South Africa
| | - Gregory L. Blatch
- Biomedical Biotechnology Research Unit, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, South Africa
- College of Health and Biomedicine, Victoria University, Melbourne, Victoria 8001, Australia
| | - Aileen Boshoff
- Biotechnology Innovation Centre, Rhodes University, Grahamstown 6140, South Africa
- * E-mail:
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11
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Borges JC, Seraphim TV, Dores-Silva PR, Barbosa LRS. A review of multi-domain and flexible molecular chaperones studies by small-angle X-ray scattering. Biophys Rev 2016; 8:107-120. [PMID: 28510050 PMCID: PMC5425780 DOI: 10.1007/s12551-016-0194-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 02/02/2016] [Indexed: 02/06/2023] Open
Abstract
Intrinsic flexibility is closely related to protein function, and a plethora of important regulatory proteins have been found to be flexible, multi-domain or even intrinsically disordered. On the one hand, understanding such systems depends on how these proteins behave in solution. On the other, small-angle X-ray scattering (SAXS) is a technique that fulfills the requirements to study protein structure and dynamics relatively quickly with few experimental limitations. Molecular chaperones from Hsp70 and Hsp90 families are multi-domain proteins containing flexible and/or disordered regions that play central roles in cellular proteostasis. Here, we review the structure and function of these proteins by SAXS. Our general approach includes the use of SAXS data to determine size and shape parameters, as well as protein shape reconstruction and their validation by using accessory biophysical tools. Some remarkable examples are presented that exemplify the potential of the SAXS technique. Protein structure can be determined in solution even at limiting protein concentrations (for example, human mortalin, a mitochondrial Hsp70 chaperone). The protein organization, flexibility and function (for example, the J-protein co-chaperones), oligomeric status, domain organization, and flexibility (for the Hsp90 chaperone and the Hip and Hep1 co-chaperones) may also be determined. Lastly, the shape, structural conservation, and protein dynamics (for the Hsp90 chaperone and both p23 and Aha1 co-chaperones) may be studied by SAXS. We believe this review will enhance the application of the SAXS technique to the study of the molecular chaperones.
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Affiliation(s)
- Júlio C Borges
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil.
| | - Thiago V Seraphim
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
| | - Paulo R Dores-Silva
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
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12
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Ostojić J, Panozzo C, Bourand-Plantefol A, Herbert CJ, Dujardin G, Bonnefoy N. Ribosome recycling defects modify the balance between the synthesis and assembly of specific subunits of the oxidative phosphorylation complexes in yeast mitochondria. Nucleic Acids Res 2016; 44:5785-97. [PMID: 27257059 PMCID: PMC4937339 DOI: 10.1093/nar/gkw490] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 05/20/2016] [Indexed: 01/07/2023] Open
Abstract
Mitochondria have their own translation machinery that produces key subunits of the OXPHOS complexes. This machinery relies on the coordinated action of nuclear-encoded factors of bacterial origin that are well conserved between humans and yeast. In humans, mutations in these factors can cause diseases; in yeast, mutations abolishing mitochondrial translation destabilize the mitochondrial DNA. We show that when the mitochondrial genome contains no introns, the loss of the yeast factors Mif3 and Rrf1 involved in ribosome recycling neither blocks translation nor destabilizes mitochondrial DNA. Rather, the absence of these factors increases the synthesis of the mitochondrially-encoded subunits Cox1, Cytb and Atp9, while strongly impairing the assembly of OXPHOS complexes IV and V. We further show that in the absence of Rrf1, the COX1 specific translation activator Mss51 accumulates in low molecular weight forms, thought to be the source of the translationally-active form, explaining the increased synthesis of Cox1. We propose that Rrf1 takes part in the coordination between translation and OXPHOS assembly in yeast mitochondria. These interactions between general and specific translation factors might reveal an evolutionary adaptation of the bacterial translation machinery to the set of integral membrane proteins that are translated within mitochondria.
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Affiliation(s)
- Jelena Ostojić
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, UEVE, 91198, Gif-sur-Yvette cedex, France
| | - Cristina Panozzo
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, UEVE, 91198, Gif-sur-Yvette cedex, France
| | - Alexa Bourand-Plantefol
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, UEVE, 91198, Gif-sur-Yvette cedex, France
| | - Christopher J Herbert
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, UEVE, 91198, Gif-sur-Yvette cedex, France
| | - Geneviève Dujardin
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, UEVE, 91198, Gif-sur-Yvette cedex, France
| | - Nathalie Bonnefoy
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, UEVE, 91198, Gif-sur-Yvette cedex, France
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13
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Dores-Silva PR, Beloti LL, Minari K, Silva SMO, Barbosa LRS, Borges JC. Structural and functional studies of Hsp70-escort protein--Hep1--of Leishmania braziliensis. Int J Biol Macromol 2015; 79:903-12. [PMID: 26071939 DOI: 10.1016/j.ijbiomac.2015.05.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 05/22/2015] [Accepted: 05/23/2015] [Indexed: 12/14/2022]
Abstract
Hep1 is a mitochondrial Hsp70 (mtHsp70) co-chaperone that presents a zinc finger domain essential for its function. This co-chaperone acts to maintain mtHsp70 in its soluble and functional state. In this work, we have demonstrated that Leishmania braziliensis mtHsp70 (LbmtHsp70) is also dependent on the assistance of Hep1. To understand the L. braziliensis Hep1 (LbHep1) structure-function relationship, we produced LbHep1 and two truncated mutants corresponding to the C-terminal zinc finger domain and the N-terminal region. We observed that LbHep1 is composed of an unfolded N-terminal region and a β-sheet-folded C-terminal domain, which holds the zinc-binding motif. Both LbHep1 and the zinc finger domain construction maintained LbmtHsp70 solubility in co-expression systems after cell lysis. In solution, LbHep1 behaved as a highly elongated monomer, probably due to the unfolded N-terminal region. Furthermore, we also observed that the zinc ion interacted with LbHep1 with high affinity and was critical for LbHep1 structure and stability because its removal from LbHep1 solutions altered the protein structure and stability. In vitro, LbHep1 protected, in sub-stoichiometric fashion, LbmtHsp70 from thermally induced aggregation but did not present intrinsic chaperone activity on model client proteins. Therefore, LbHep1 is a specific chaperone for LbmtHsp70.
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Affiliation(s)
- P R Dores-Silva
- Institute of Chemistry of São Carlos, University of São Paulo - USP, São Carlos, SP 13560-970, Brazil
| | - L L Beloti
- Institute of Chemistry of São Carlos, University of São Paulo - USP, São Carlos, SP 13560-970, Brazil
| | - K Minari
- Institute of Chemistry of São Carlos, University of São Paulo - USP, São Carlos, SP 13560-970, Brazil; Post-Graduation Program in Evolutionary Genetics and Molecular Biology, Federal University of São Carlos - UFSCar, São Carlos, SP 13565-905, Brazil
| | - S M O Silva
- Institute of Chemistry of São Carlos, University of São Paulo - USP, São Carlos, SP 13560-970, Brazil
| | - L R S Barbosa
- Institute of Physics, University of São Paulo - USP, São Paulo, SP 05508-090, Brazil
| | - J C Borges
- Institute of Chemistry of São Carlos, University of São Paulo - USP, São Carlos, SP 13560-970, Brazil.
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Kaniak-Golik A, Skoneczna A. Mitochondria-nucleus network for genome stability. Free Radic Biol Med 2015; 82:73-104. [PMID: 25640729 DOI: 10.1016/j.freeradbiomed.2015.01.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 11/25/2014] [Accepted: 01/13/2015] [Indexed: 12/21/2022]
Abstract
The proper functioning of the cell depends on preserving the cellular genome. In yeast cells, a limited number of genes are located on mitochondrial DNA. Although the mechanisms underlying nuclear genome maintenance are well understood, much less is known about the mechanisms that ensure mitochondrial genome stability. Mitochondria influence the stability of the nuclear genome and vice versa. Little is known about the two-way communication and mutual influence of the nuclear and mitochondrial genomes. Although the mitochondrial genome replicates independent of the nuclear genome and is organized by a distinct set of mitochondrial nucleoid proteins, nearly all genome stability mechanisms responsible for maintaining the nuclear genome, such as mismatch repair, base excision repair, and double-strand break repair via homologous recombination or the nonhomologous end-joining pathway, also act to protect mitochondrial DNA. In addition to mitochondria-specific DNA polymerase γ, the polymerases α, η, ζ, and Rev1 have been found in this organelle. A nuclear genome instability phenotype results from a failure of various mitochondrial functions, such as an electron transport chain activity breakdown leading to a decrease in ATP production, a reduction in the mitochondrial membrane potential (ΔΨ), and a block in nucleotide and amino acid biosynthesis. The loss of ΔΨ inhibits the production of iron-sulfur prosthetic groups, which impairs the assembly of Fe-S proteins, including those that mediate DNA transactions; disturbs iron homeostasis; leads to oxidative stress; and perturbs wobble tRNA modification and ribosome assembly, thereby affecting translation and leading to proteotoxic stress. In this review, we present the current knowledge of the mechanisms that govern mitochondrial genome maintenance and demonstrate ways in which the impairment of mitochondrial function can affect nuclear genome stability.
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Affiliation(s)
- Aneta Kaniak-Golik
- Laboratory of Mutagenesis and DNA Repair, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland
| | - Adrianna Skoneczna
- Laboratory of Mutagenesis and DNA Repair, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland.
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15
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Böttinger L, Oeljeklaus S, Guiard B, Rospert S, Warscheid B, Becker T. Mitochondrial heat shock protein (Hsp) 70 and Hsp10 cooperate in the formation of Hsp60 complexes. J Biol Chem 2015; 290:11611-22. [PMID: 25792736 DOI: 10.1074/jbc.m115.642017] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial Hsp70 (mtHsp70) mediates essential functions for mitochondrial biogenesis, like import and folding of proteins. In these processes, the chaperone cooperates with cochaperones, the presequence translocase, and other chaperone systems. The chaperonin Hsp60, together with its cofactor Hsp10, catalyzes folding of a subset of mtHsp70 client proteins. Hsp60 forms heptameric ring structures that provide a cavity for protein folding. How the Hsp60 rings are assembled is poorly understood. In a comprehensive interaction study, we found that mtHsp70 associates with Hsp60 and Hsp10. Surprisingly, mtHsp70 interacts with Hsp10 independently of Hsp60. The mtHsp70-Hsp10 complex binds to the unassembled Hsp60 precursor to promote its assembly into mature Hsp60 complexes. We conclude that coupling to Hsp10 recruits mtHsp70 to mediate the biogenesis of the heptameric Hsp60 rings.
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Affiliation(s)
- Lena Böttinger
- From the Institut für Biochemie und Molekularbiologie, ZBMZ, the Fakultät für Biologie
| | - Silke Oeljeklaus
- Institut für Biologie II, Abteilung Biochemie und Funktionelle Proteomik, Universität Freiburg, 79104 Freiburg, Germany, the BIOSS Centre for Biological Signalling Studies, and
| | - Bernard Guiard
- the Centre de Génétique Moléculaire, CNRS, 91190 Gif-sur-Yvette, France
| | - Sabine Rospert
- From the Institut für Biochemie und Molekularbiologie, ZBMZ, the BIOSS Centre for Biological Signalling Studies, and
| | - Bettina Warscheid
- Institut für Biologie II, Abteilung Biochemie und Funktionelle Proteomik, Universität Freiburg, 79104 Freiburg, Germany, the BIOSS Centre for Biological Signalling Studies, and
| | - Thomas Becker
- From the Institut für Biochemie und Molekularbiologie, ZBMZ, the Fakultät für Biologie, the BIOSS Centre for Biological Signalling Studies, and
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16
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Dores-Silva PR, Barbosa LRS, Ramos CHI, Borges JC. Human mitochondrial Hsp70 (mortalin): shedding light on ATPase activity, interaction with adenosine nucleotides, solution structure and domain organization. PLoS One 2015; 10:e0117170. [PMID: 25615450 PMCID: PMC4304843 DOI: 10.1371/journal.pone.0117170] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 12/19/2014] [Indexed: 12/28/2022] Open
Abstract
The human mitochondrial Hsp70, also called mortalin, is of considerable importance for mitochondria biogenesis and the correct functioning of the cell machinery. In the mitochondrial matrix, mortalin acts in the importing and folding process of nucleus-encoded proteins. The in vivo deregulation of mortalin expression and/or function has been correlated with age-related diseases and certain cancers due to its interaction with the p53 protein. In spite of its critical biological roles, structural and functional studies on mortalin are limited by its insoluble recombinant production. This study provides the first report of the production of folded and soluble recombinant mortalin when co-expressed with the human Hsp70-escort protein 1, but it is still likely prone to self-association. The monomeric fraction of mortalin presented a slightly elongated shape and basal ATPase activity that is higher than that of its cytoplasmic counterpart Hsp70-1A, suggesting that it was obtained in the functional state. Through small angle X-ray scattering, we assessed the low-resolution structural model of monomeric mortalin that is characterized by an elongated shape. This model adequately accommodated high resolution structures of Hsp70 domains indicating its quality. We also observed that mortalin interacts with adenosine nucleotides with high affinity. Thermally induced unfolding experiments indicated that mortalin is formed by at least two domains and that the transition is sensitive to the presence of adenosine nucleotides and that this process is dependent on the presence of Mg2+ ions. Interestingly, the thermal-induced unfolding assays of mortalin suggested the presence of an aggregation/association event, which was not observed for human Hsp70-1A, and this finding may explain its natural tendency for in vivo aggregation. Our study may contribute to the structural understanding of mortalin as well as to contribute for its recombinant production for antitumor compound screenings.
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Affiliation(s)
- Paulo R Dores-Silva
- Institute of Chemistry of Sao Carlos, University of Sao Paulo, Sao Carlos, SP, P.O. Box 780, 13560-970, Brazil
| | - Leandro R S Barbosa
- Institute of Physics, University of Sao Paulo, Sao Paulo, SP, 05508-090, Brazil
| | - Carlos H I Ramos
- Institute of Chemistry, University of Campinas-UNICAMP, P.O. Box 6154, 13083-970, Campinas, SP, Brazil
| | - Júlio C Borges
- Institute of Chemistry of Sao Carlos, University of Sao Paulo, Sao Carlos, SP, P.O. Box 780, 13560-970, Brazil
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Trösch R, Mühlhaus T, Schroda M, Willmund F. ATP-dependent molecular chaperones in plastids--More complex than expected. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:872-88. [PMID: 25596449 DOI: 10.1016/j.bbabio.2015.01.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/03/2015] [Accepted: 01/08/2015] [Indexed: 11/27/2022]
Abstract
Plastids are a class of essential plant cell organelles comprising photosynthetic chloroplasts of green tissues, starch-storing amyloplasts of roots and tubers or the colorful pigment-storing chromoplasts of petals and fruits. They express a few genes encoded on their organellar genome, called plastome, but import most of their proteins from the cytosol. The import into plastids, the folding of freshly-translated or imported proteins, the degradation or renaturation of denatured and entangled proteins, and the quality-control of newly folded proteins all require the action of molecular chaperones. Members of all four major families of ATP-dependent molecular chaperones (chaperonin/Cpn60, Hsp70, Hsp90 and Hsp100 families) have been identified in plastids from unicellular algae to higher plants. This review aims not only at giving an overview of the most current insights into the general and conserved functions of these plastid chaperones, but also into their specific plastid functions. Given that chloroplasts harbor an extreme environment that cycles between reduced and oxidized states, that has to deal with reactive oxygen species and is highly reactive to environmental and developmental signals, it can be presumed that plastid chaperones have evolved a plethora of specific functions some of which are just about to be discovered. Here, the most urgent questions that remain unsolved are discussed, and guidance for future research on plastid chaperones is given. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Affiliation(s)
- Raphael Trösch
- TU Kaiserslautern, Molecular Biotechnology & Systems Biology, Paul-Ehrlich-Straße 23, 67663 Kaiserslautern, Germany; HU Berlin, Institute of Biology, Chausseestraße 117, 10115 Berlin, Germany; TU Kaiserslautern, Molecular Genetics of Eukaryotes, Paul-Ehrlich-Straße 23, 67663 Kaiserslautern, Germany.
| | - Timo Mühlhaus
- TU Kaiserslautern, Molecular Biotechnology & Systems Biology, Paul-Ehrlich-Straße 23, 67663 Kaiserslautern, Germany.
| | - Michael Schroda
- TU Kaiserslautern, Molecular Biotechnology & Systems Biology, Paul-Ehrlich-Straße 23, 67663 Kaiserslautern, Germany.
| | - Felix Willmund
- TU Kaiserslautern, Molecular Genetics of Eukaryotes, Paul-Ehrlich-Straße 23, 67663 Kaiserslautern, Germany.
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18
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Regev-Rudzki N, Gabriel K, Bursać D. The evolution and function of co-chaperones in mitochondria. Subcell Biochem 2015; 78:201-217. [PMID: 25487023 DOI: 10.1007/978-3-319-11731-7_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Mitochondrial chaperones mediate and affect critical organellar processes, essential for cellular function. These chaperone systems have both prokaryotic and eukaryotic features. While some of the mitochondrial co-chaperones have clear homologues in prokaryotes, some are unique to eukaryotes and have no homologues in the chaperone machinery of other cellular compartments. The mitochondrial co-chaperones are required for protein import into the organelle and in enforcing the structure of the main chaperones. In addition to novel types of interaction with their senior partners, unexpected and essential interactions between the co-chaperones themselves have recently been described.
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Affiliation(s)
- Neta Regev-Rudzki
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovolt, Israel,
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19
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Talla V, Porciatti V, Chiodo V, Boye SL, Hauswirth WW, Guy J. Gene therapy with mitochondrial heat shock protein 70 suppresses visual loss and optic atrophy in experimental autoimmune encephalomyelitis. Invest Ophthalmol Vis Sci 2014; 55:5214-26. [PMID: 25015358 DOI: 10.1167/iovs.14-14688] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
PURPOSE To rescue visual loss and optic neuropathy in experimental autoimmune encephalomyelitis (EAE). METHODS Encephalomyelitis was induced in mice that received intravitreal injections of AAV2-mtHSP70Flag or AAV2-Cox8-mCherry. Additional mice were injected with AAV2-Cox8-mCherry, but not sensitized for EAE. Visual function was assessed by pattern electroretinograms (PERG) at 1, 3, and 6 months post injection (MPI). Optical coherence tomography (OCT) evaluated the thickness of the inner plexiform layer + nerve fiber layers at 1, 3, and 6 MPI. Retinas and optic nerves (ONs) of mice euthanized 6 MPI were processed for light and electron microscopy. Expression of mtHSP70Flag in the retina and ONs was evaluated by RT-PCR, immunofluorescence, and Western blotting. The activities of respiratory complexes I and III, as well as mitochondrial protein import were quantitated. RESULTS Expression: immunofluorescence revealed punctate and perinuclear expression of mtHSP70Flag that colocalized with mitochondrial porin in thy1.2 labeled retinal ganglion cells (RGCs). Immunoblotting and RT-PCR confirmed mtHSP70Flag expression in the retina and ON. Rescue: treatment with mtHSP70Flag resulted in a 44% increase in PERG amplitude and less delays in latency relative to the EAE-mCherry group that also showed progressive inner retinal thinning. At 6 MPI, the almost 50% loss of RGCs and optic nerve axons in EAE mice was suppressed by mtHSP70Flag. In addition, retinas of EAE-mtHSP70Flag mice showed nearly complete rescue of complex I and III activities that was reduced by one-third in the EAE-mCherry retinas. Lastly, reductions in import of COX8-mCherry into mitochondria of mice sensitized for EAE improved by 30% with mtHSP70Flag gene therapy. CONCLUSIONS Mitochondrial HSP70 ameliorates mitochondrial dysfunction that culminates in irreversible visual loss and atrophy of the optic nerve in EAE suggesting that it may be useful to prevent irreversible disability in patients with optic neuritis and multiple sclerosis (MS).
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Affiliation(s)
- Venu Talla
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miller School of Medicine, Miami, Florida, United States
| | - Vittorio Porciatti
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miller School of Medicine, Miami, Florida, United States
| | - Vince Chiodo
- Department of Ophthalmology, University of Florida, Gainesville, Florida, United States
| | - Sanford L Boye
- Department of Ophthalmology, University of Florida, Gainesville, Florida, United States
| | - William W Hauswirth
- Department of Ophthalmology, University of Florida, Gainesville, Florida, United States
| | - John Guy
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miller School of Medicine, Miami, Florida, United States
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20
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Lewrenz I, Rietzschel N, Guiard B, Lill R, van der Laan M, Voos W. The functional interaction of mitochondrial Hsp70s with the escort protein Zim17 is critical for Fe/S biogenesis and substrate interaction at the inner membrane preprotein translocase. J Biol Chem 2013; 288:30931-43. [PMID: 24030826 DOI: 10.1074/jbc.m113.465997] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The yeast protein Zim17 belongs to a unique class of co-chaperones that maintain the solubility of Hsp70 proteins in mitochondria and plastids of eukaryotic cells. However, little is known about the functional cooperation between Zim17 and mitochondrial Hsp70 proteins in vivo. To analyze the effects of a loss of Zim17 function in the authentic environment, we introduced novel conditional mutations within the ZIM17 gene of the model organism Saccharomyces cerevisiae that allowed a recovery of temperature-sensitive but respiratory competent zim17 mutant cells. On fermentable growth medium, the mutant cells were prone to acquire respiratory deficits and showed a strong aggregation of the mitochondrial Hsp70 Ssq1 together with a concomitant defect in Fe/S protein biogenesis. In contrast, under respiring conditions, the mitochondrial Hsp70s Ssc1 and Ssq1 exhibited only a partial aggregation. We show that the induction of the zim17 mutant phenotype leads to strong import defects for Ssc1-dependent matrix-targeted precursor proteins that correlate with a significantly reduced binding of newly imported substrate proteins to Ssc1. We conclude that Zim17 is not only required for the maintenance of mtHsp70 solubility but also directly assists the functional interaction of mtHsp70 with substrate proteins in a J-type co-chaperone-dependent manner.
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Affiliation(s)
- Ilka Lewrenz
- From the Institut für Biochemie und Molekularbiologie, Universität Bonn, Nussallee 11, D-53115 Bonn, Germany
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21
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Lionaki E, Tavernarakis N. Oxidative stress and mitochondrial protein quality control in aging. J Proteomics 2013; 92:181-94. [PMID: 23563202 DOI: 10.1016/j.jprot.2013.03.022] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 02/22/2013] [Accepted: 03/25/2013] [Indexed: 12/17/2022]
Abstract
Mitochondrial protein quality control incorporates an elaborate network of chaperones and proteases that survey the organelle for misfolded or unfolded proteins and toxic aggregates. Repair of misfolded or aggregated protein and proteolytic removal of irreversibly damaged proteins are carried out by the mitochondrial protein quality control system. Initial maturation and folding of the nuclear or mitochondrial-encoded mitochondrial proteins are mediated by processing peptidases and chaperones that interact with the protein translocation machinery. Mitochondrial proteins are subjected to cumulative oxidative damage. Thus, impairment of quality control processes may cause mitochondrial dysfunction. Aging has been associated with a marked decline in the effectiveness of mitochondrial protein quality control. Here, we present an overview of the chaperones and proteases involved in the initial folding and maturation of new, incoming precursor molecules, and the subsequent repair and removal of oxidized aggregated proteins. In addition, we highlight the link between mitochondrial protein quality control mechanisms and the aging process. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.
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Affiliation(s)
- Eirini Lionaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 71110, Crete, Greece
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22
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Dores-Silva PR, Minari K, Ramos CHI, Barbosa LRS, Borges JC. Structural and stability studies of the human mtHsp70-escort protein 1: an essential mortalin co-chaperone. Int J Biol Macromol 2013; 56:140-8. [PMID: 23462535 DOI: 10.1016/j.ijbiomac.2013.02.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 02/07/2013] [Accepted: 02/09/2013] [Indexed: 11/20/2022]
Abstract
Mitochondrial Hsp70 is involved in both protein import and folding process, among other essential functions. In mammalian cells, due to its role in the malignant process, it receives the name of mortalin. Despite its importance in protein and mitochondrial homeostasis, mortalin tends to self-aggregate in vitro and in vivo, the later leads to mitochondrial biogenesis failure. Recently, a zinc-finger protein, named Hsp70-escort protein 1 (Hep1, also called Zim17/TIM15/DNLZ), was described as an essential human mitochondrial mortalin co-chaperone which avoids its self-aggregation. Here, we report structural studies of the human Hep1 (hHep1). The results indicate that hHep1 shares some structural similarities with the yeast ortholog despite the low identity and functional differences. We also observed that hHep1 oligomerizes in a concentration-dependent fashion and that the zinc ion, which is essential for hHep1 in vivo function, has an important protein-structure stabilizing effect.
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Affiliation(s)
- P R Dores-Silva
- Instituto de Química de São Carlos, Universidade de São Paulo - USP, São Carlos, SP 13560-970, Brazil
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23
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Fraga H, Papaleo E, Vega S, Velazquez-Campoy A, Ventura S. Zinc induced folding is essential for TIM15 activity as an mtHsp70 chaperone. Biochim Biophys Acta Gen Subj 2013; 1830:2139-49. [DOI: 10.1016/j.bbagen.2012.10.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 09/21/2012] [Accepted: 10/03/2012] [Indexed: 11/15/2022]
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24
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Patil VA, Fox JL, Gohil VM, Winge DR, Greenberg ML. Loss of cardiolipin leads to perturbation of mitochondrial and cellular iron homeostasis. J Biol Chem 2012. [PMID: 23192348 DOI: 10.1074/jbc.m112.428938] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Cardiolipin (CL) is the signature phospholipid of mitochondrial membranes, where it is synthesized locally and plays a critical role in mitochondrial bioenergetic functions. The importance of CL in human health is underscored by the observation that perturbation of CL biosynthesis causes the severe genetic disorder Barth syndrome. To fully understand the cellular response to the loss of CL, we carried out genome-wide expression profiling of the yeast CL mutant crd1Δ. Our results show that the loss of CL in this mutant leads to increased expression of iron uptake genes accompanied by elevated levels of mitochondrial iron and increased sensitivity to iron and hydrogen peroxide. Previous studies have shown that increased mitochondrial iron levels result from perturbations in iron-sulfur (Fe-S) cluster biogenesis. Consistent with an Fe-S defect, deletion of ISU1, one of two ISU genes that encode the mitochondrial Fe-S scaffolding protein essential for the synthesis of Fe-S clusters, led to synthetic growth defects with the crd1Δ mutant. We further show that crd1Δ cells have reduced activities of mitochondrial Fe-S enzymes (aconitase, succinate dehydrogenase, and ubiquinol-cytochrome c oxidoreductase), as well as cytosolic Fe-S enzymes (sulfite reductase and isopropylmalate isomerase). Increased expression of ATM1 or YAP1 did not rescue the Fe-S defects in crd1Δ. These findings show for the first time that CL is required for Fe-S biogenesis to maintain mitochondrial and cellular iron homeostasis.
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Affiliation(s)
- Vinay A Patil
- Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202, USA
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25
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Abstract
Hep1 acts as a specialized chaperone to mediate the de novo folding of yeast mitochondrial Hsp70. Chaperones mediate protein folding and prevent deleterious protein aggregation in the cell. However, little is known about the biogenesis of chaperones themselves. In this study, we report on the biogenesis of the yeast mitochondrial Hsp70 (mtHsp70) chaperone, which is essential for the functionality of mitochondria. We show in vivo and in organello that mtHsp70 rapidly folds after its import into mitochondria, with its ATPase domain and peptide-binding domain (PBD) adopting their structures independently of each other. Importantly, folding of the ATPase domain but not of the PBD was severely affected in the absence of the Hsp70 escort protein, Hep1. We reconstituted the folding of mtHsp70, demonstrating that Hep1 and ATP/ADP were required and sufficient for its de novo folding. Our data show that Hep1 bound to a folding intermediate of mtHsp70. Binding of an adenine nucleotide triggered release of Hep1 and folding of the intermediate into native mtHsp70. Thus, Hep1 acts as a specialized chaperone mediating the de novo folding of an Hsp70 chaperone.
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Affiliation(s)
- Marta Blamowska
- Adolf-Butenandt-Institut, Lehrstuhl für Physiologische Chemie, Ludwig-Maximilians-Universität München, 81377 München, Germany
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26
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Kluth J, Schmidt A, März M, Krupinska K, Lorbiecke R. Arabidopsis
Zinc Ribbon 3 is the ortholog of yeast mitochondrial HSP70 escort protein HEP1 and belongs to an ancient protein family in mitochondria and plastids. FEBS Lett 2012; 586:3071-6. [DOI: 10.1016/j.febslet.2012.07.052] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/02/2012] [Accepted: 07/05/2012] [Indexed: 01/14/2023]
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27
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Walls KC, Coskun P, Gallegos-Perez JL, Zadourian N, Freude K, Rasool S, Blurton-Jones M, Green KN, LaFerla FM. Swedish Alzheimer mutation induces mitochondrial dysfunction mediated by HSP60 mislocalization of amyloid precursor protein (APP) and beta-amyloid. J Biol Chem 2012; 287:30317-27. [PMID: 22753410 DOI: 10.1074/jbc.m112.365890] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Alzheimer disease (AD) is a complex disorder that involves numerous cellular and subcellular alterations including impairments in mitochondrial homeostasis. To better understand the role of mitochondrial dysfunction in the pathogenesis of AD, we analyzed brains from clinically well-characterized human subjects and from the 3xTg-AD mouse model of AD. We find Aβ and critical components of the γ-secretase complex, presenilin-1, -2, and nicastrin, accumulate in the mitochondria. We used a proteomics approach to identify binding partners and show that heat shock protein 60 (HSP60), a molecular chaperone localized to mitochondria and the plasma membrane, specifically associates with APP. We next generated stable neural cell lines expressing human wild-type or Swedish APP, and provide corroborating in vitro evidence that HSP60 mediates translocation of APP to the mitochondria. Viral-mediated shRNA knockdown of HSP60 attenuates APP and Aβ mislocalization to the mitochondria. Our findings identify a novel interaction between APP and HSP60, which accounts for its translocation to the mitochondria.
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Affiliation(s)
- Ken Carlson Walls
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-4545, USA.
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28
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Vu MT, Zhai P, Lee J, Guerra C, Liu S, Gustin MC, Silberg JJ. The DNLZ/HEP zinc-binding subdomain is critical for regulation of the mitochondrial chaperone HSPA9. Protein Sci 2012; 21:258-67. [PMID: 22162012 DOI: 10.1002/pro.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 11/04/2011] [Accepted: 11/27/2011] [Indexed: 01/20/2023]
Abstract
Human mitochondrial DNLZ/HEP regulates the catalytic activity and solubility of the mitochondrial hsp70 chaperone HSPA9. Here, we investigate the role that the DNLZ zinc-binding and C-terminal subdomains play in regulating HSPA9. We show that truncations lacking portions of the zinc-binding subdomain (ZBS) do not affect the solubility of HSPA9 or its ATPase domain, whereas those containing the ZBS and at least 10 residues following this subdomain enhance chaperone solubility. Binding measurements further show that DNLZ requires its ZBS to form a stable complex with the HSPA9 ATPase domain, and ATP hydrolysis measurements reveal that the ZBS is critical for full stimulation of HSPA9 catalytic activity. We also examined if DNLZ is active in vivo. We found that DNLZ partially complements the growth of Δzim17 Saccharomyces cerevisiae, and we discovered that a Zim17 truncation lacking a majority of the C-terminal subdomain strongly complements growth like full-length Zim17. These findings provide direct evidence that human DNLZ is a functional ortholog of Zim17. In addition, they implicate the pair of antiparallel β-strands that coordinate zinc in Zim17/DNLZ-type proteins as critical for binding and regulating hsp70 chaperones.
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Affiliation(s)
- Michael T Vu
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251, USA
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Díaz de la Loza MDC, Gallardo M, García-Rubio ML, Izquierdo A, Herrero E, Aguilera A, Wellinger RE. Zim17/Tim15 links mitochondrial iron-sulfur cluster biosynthesis to nuclear genome stability. Nucleic Acids Res 2011; 39:6002-15. [PMID: 21511814 PMCID: PMC3152343 DOI: 10.1093/nar/gkr193] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Genomic instability is related to a wide-range of human diseases. Here, we show that mitochondrial iron–sulfur cluster biosynthesis is important for the maintenance of nuclear genome stability in Saccharomyces cerevisiae. Cells lacking the mitochondrial chaperone Zim17 (Tim15/Hep1), a component of the iron–sulfur biosynthesis machinery, have limited respiration activity, mimic the metabolic response to iron starvation and suffer a dramatic increase in nuclear genome recombination. Increased oxidative damage or deficient DNA repair do not account for the observed genomic hyperrecombination. Impaired cell-cycle progression and genetic interactions of ZIM17 with components of the RFC-like complex involved in mitotic checkpoints indicate that replicative stress causes hyperrecombination in zim17Δ mutants. Furthermore, nuclear accumulation of pre-ribosomal particles in zim17Δ mutants reinforces the importance of iron–sulfur clusters in normal ribosome biosynthesis. We propose that compromised ribosome biosynthesis and cell-cycle progression are interconnected, together contributing to replicative stress and nuclear genome instability in zim17Δ mutants.
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Affiliation(s)
- María Del Carmen Díaz de la Loza
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, Avd Américo Vespucio, 41092 Sevilla, Spain
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30
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Zhai P, Vu MT, Hoff KG, Silberg JJ. A conserved histidine in human DNLZ/HEP is required for stimulation of HSPA9 ATPase activity. Biochem Biophys Res Commun 2011; 408:589-94. [PMID: 21530495 DOI: 10.1016/j.bbrc.2011.04.066] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 04/15/2011] [Indexed: 11/17/2022]
Abstract
The DNL-type zinc-finger protein DNLZ regulates the activity and solubility of the human mitochondrial chaperone HSPA9. To identify DNLZ residues that are critical for chaperone regulation, we carried out an alanine mutagenesis scan of charged residues in a W115I mutant of human DNLZ and assessed the effect of each mutation on interactions with HSPA9. All mutants analyzed promote the solubility of HSPA9 upon expression in Escherichia coli. However, binding studies examining the effect of DNLZ mutants on chaperone tryptophan fluorescence identified three mutations (R81A, H107A, and D111A) that decrease DNLZ binding affinity for nucleotide-free chaperone. In addition, ATPase measurements revealed that DNLZ-R81A and DNLZ-D111A both stimulate the catalytic activity HSPA9, whereas DNLZ-H107A does not elicit an increase in activity even when present at a concentration that is 10-fold higher than the level required for half-maximal stimulation by DNLZ. These findings implicate a conserved histidine as critical for DNLZ regulation of mitochondrial HSPA9 catalytic activity.
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Affiliation(s)
- Peng Zhai
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251, USA
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31
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Endo T, Yamano K, Kawano S. Structural insight into the mitochondrial protein import system. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:955-70. [DOI: 10.1016/j.bbamem.2010.07.018] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2010] [Revised: 07/13/2010] [Accepted: 07/19/2010] [Indexed: 11/28/2022]
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32
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Burbulla LF, Schelling C, Kato H, Rapaport D, Woitalla D, Schiesling C, Schulte C, Sharma M, Illig T, Bauer P, Jung S, Nordheim A, Schöls L, Riess O, Krüger R. Dissecting the role of the mitochondrial chaperone mortalin in Parkinson's disease: functional impact of disease-related variants on mitochondrial homeostasis. Hum Mol Genet 2010; 19:4437-52. [PMID: 20817635 DOI: 10.1093/hmg/ddq370] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The mitochondrial chaperone mortalin has been linked to neurodegeneration in Parkinson's disease (PD) based on reduced protein levels in affected brain regions of PD patients and its interaction with the PD-associated protein DJ-1. Recently, two amino acid exchanges in the ATPase domain (R126W) and the substrate-binding domain (P509S) of mortalin were identified in Spanish PD patients. Here, we identified a separate and novel variant (A476T) in the substrate-binding domain of mortalin in German PD patients. To define a potential role as a susceptibility factor in PD, we characterized the functions of all three variants in different cellular models. In vitro import assays revealed normal targeting of all mortalin variants. In neuronal and non-neuronal human cell lines, the disease-associated variants caused a mitochondrial phenotype of increased reactive oxygen species and reduced mitochondrial membrane potential, which were exacerbated upon proteolytic stress. These functional impairments correspond with characteristic alterations of the mitochondrial network in cells overexpressing mutant mortalin compared with wild-type (wt), which were confirmed in fibroblasts from a carrier of the A476T variant. In line with a loss of function hypothesis, knockdown of mortalin in human cells caused impaired mitochondrial function that was rescued by wt mortalin, but not by the variants. Our genetic and functional studies of novel disease-associated variants in the mortalin gene define a loss of mortalin function, which causes impaired mitochondrial function and dynamics. Our results support the role of this mitochondrial chaperone in neurodegeneration and underscore the concept of impaired mitochondrial protein quality control in PD.
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Affiliation(s)
- Lena F Burbulla
- DZNE, German Center for Neurodegenerative Diseases, Tübingen, Germany
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New Insights into the Roles of Molecular Chaperones in Chlamydomonas and Volvox. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 285:75-113. [DOI: 10.1016/b978-0-12-381047-2.00002-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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34
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Blamowska M, Sichting M, Mapa K, Mokranjac D, Neupert W, Hell K. ATPase domain and interdomain linker play a key role in aggregation of mitochondrial Hsp70 chaperone Ssc1. J Biol Chem 2009; 285:4423-31. [PMID: 20007714 DOI: 10.1074/jbc.m109.061697] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The co-chaperone Hep1 is required to prevent the aggregation of mitochondrial Hsp70 proteins. We have analyzed the interaction of Hep1 with mitochondrial Hsp70 (Ssc1) and the determinants in Ssc1 that make it prone to aggregation. The ATPase and peptide binding domain (PBD) of Hsp70 proteins are connected by a linker segment that mediates interdomain communication between the domains. We show here that the minimal Hep1 binding entity of Ssc1 consists of the ATPase domain and the interdomain linker. In the absence of Hep1, the ATPase domain with the interdomain linker had the tendency to aggregate, in contrast to the ATPase domain with the mutated linker segment or without linker, and in contrast to the PBD. The closest homolog of Ssc1, bacterial DnaK, and a Ssc1 chimera, in which a segment of the ATPase domain of Ssc1 was replaced by the corresponding segment from DnaK, did not aggregate in Delta hep1 mitochondria. The propensity to aggregate appears to be a specific property of the mitochondrial Hsp70 proteins. The ATPase domain in combination with the interdomain linker is crucial for aggregation of Ssc1. In conclusion, our results suggest that interdomain communication makes Ssc1 prone to aggregation. Hep1 counteracts aggregation by binding to this aggregation-prone conformer.
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Affiliation(s)
- Marta Blamowska
- Adolf-Butenandt-Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5, 81377 München, Germany
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35
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Abstract
Abstract
Mitochondria are two-membrane bounded organelles consisting of 1000–2000 different proteins, most of which are synthesized in the cytosol and subsequently imported into mitochondria. The imported proteins are further sorted to one of the four compartments, the outer membrane, intermembrane space, inner membrane, and matrix, mostly following one of the five major pathways. Mitochondrial protein import and sorting are mediated by the translocator complexes in the membranes and chaperones in the aqueous compartments operating along the import pathways. Here, we summarize the expanding knowledge on the roles of translocators, chaperones, and related components in the multiple pathways for mitochondrial protein trafficking.
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Tamura Y, Endo T, Iijima M, Sesaki H. Ups1p and Ups2p antagonistically regulate cardiolipin metabolism in mitochondria. ACTA ACUST UNITED AC 2009; 185:1029-45. [PMID: 19506038 PMCID: PMC2711612 DOI: 10.1083/jcb.200812018] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiolipin, a unique phospholipid composed of four fatty acid chains, is located mainly in the mitochondrial inner membrane (IM). Cardiolipin is required for the integrity of several protein complexes in the IM, including the TIM23 translocase, a dynamic complex which mediates protein import into the mitochondria through interactions with the import motor presequence translocase–associated motor (PAM). In this study, we report that two homologous intermembrane space proteins, Ups1p and Ups2p, control cardiolipin metabolism and affect the assembly state of TIM23 and its association with PAM in an opposing manner. In ups1Δ mitochondria, cardiolipin levels were decreased, and the TIM23 translocase showed altered conformation and decreased association with PAM, leading to defects in mitochondrial protein import. Strikingly, loss of Ups2p restored normal cardiolipin levels and rescued TIM23 defects in ups1Δ mitochondria. Furthermore, we observed synthetic growth defects in ups mutants in combination with loss of Pam17p, which controls the integrity of PAM. Our findings provide a novel molecular mechanism for the regulation of cardiolipin metabolism.
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Affiliation(s)
- Yasushi Tamura
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Deocaris CC, Kaul SC, Wadhwa R. From proliferative to neurological role of an hsp70 stress chaperone, mortalin. Biogerontology 2008; 9:391-403. [PMID: 18770009 DOI: 10.1007/s10522-008-9174-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2008] [Accepted: 08/18/2008] [Indexed: 12/21/2022]
Abstract
Although the brain makes up approximately 2% of a person's body weight, it consumes more than 15% of total cardiac output and has a per capita caloric requirement of 10 times more than the rest of the body. Such continuous metabolic demand that supports the generation of action potentials in neuronal cells relies on the mitochondria, the main organelle for power generation. The phenomenon of mitochondrial biogenesis, although has long been a neglected theme in neurobiology, can be regarded as critical to brain physiology. The present review emphasizes the role of a key molecular player of mitochondrial biogenesis, the mortalin/mthsp70. Brain mortalin is discussed in relation to its aptitude to impact on mitochondrial function and homeostasis, to its interfacing energy metabolic functions with synaptic plasticity, and to its modulation of brain aging via the cellular senescence pathways. Recently, this chaperone has been implicated in Alzheimer's (AD) and Parkinson's (PD) diseases, with proteomic studies consistently identifying oxidatively-damaged mortalin as potential biomarker. Hence, it is possible that mitochondrial dysfunction coincides with the collapse in the mitochondrial chaperone network that aim not only to import, sort and maintain integrity of protein components within the mitochondria, but also to act as buffer to the molecular heterogeneity of damaged and aging mitochondrial proteins within a ROS-rich microenvironment. Inversely, it may also seem that vulnerability to mitochondrial dysfunction could be precipitated by malevolent (anti-chaperone) gain-of-function of a 'sick mortalin'.
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Affiliation(s)
- Custer C Deocaris
- Institute of Health and Sports Science, University of Tsukuba, Ibaraki, 305-8574, Japan
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Zhai P, Stanworth C, Liu S, Silberg JJ. The human escort protein Hep binds to the ATPase domain of mitochondrial hsp70 and regulates ATP hydrolysis. J Biol Chem 2008; 283:26098-106. [PMID: 18632665 DOI: 10.1074/jbc.m803475200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hsp70 escort proteins (Hep) have been implicated as essential for maintaining the function of yeast mitochondrial hsp70 molecular chaperones (mtHsp70), but the role that escort proteins play in regulating mammalian chaperone folding and function has not been established. We present evidence that human mtHsp70 exhibits limited solubility due to aggregation mediated by its ATPase domain and show that human Hep directly enhances chaperone solubility through interactions with this domain. In the absence of Hep, mtHsp70 was insoluble when expressed in Escherichia coli, as was its isolated ATPase domain and a chimera having this domain fused to the peptide-binding domain of HscA, a soluble monomeric chaperone. In contrast, these proteins all exhibited increased solubility when expressed in the presence of Hep. In vitro studies further revealed that purified Hep regulates the interaction of mtHsp70 with nucleotides. Full-length mtHsp70 exhibited slow intrinsic ATP hydrolysis activity (6.8+/-0.2 x 10(-4) s(-1)) at 25 degrees C, which was stimulated up to 49-fold by Hep. Hep also stimulated the activity of the isolated ATPase domain, albeit to a lower maximal extent (11.5-fold). In addition, gel-filtration studies showed that formation of chaperone-escort protein complexes inhibited mtHsp70 self-association, and they revealed that Hep binding to full-length mtHsp70 and its isolated ATPase domain is strongest in the absence of nucleotides. These findings provide evidence that metazoan escort proteins regulate the catalytic activity and solubility of their cognate chaperones, and they indicate that both forms of regulation arise from interactions with the mtHsp70 ATPase domain.
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Affiliation(s)
- Peng Zhai
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251, USA
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39
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Willmund F, Hinnenberger M, Nick S, Schulz-Raffelt M, Mühlhaus T, Schroda M. Assistance for a Chaperone. J Biol Chem 2008; 283:16363-73. [DOI: 10.1074/jbc.m708431200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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40
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Becker T, Pfannschmidt S, Guiard B, Stojanovski D, Milenkovic D, Kutik S, Pfanner N, Meisinger C, Wiedemann N. Biogenesis of the Mitochondrial TOM Complex. J Biol Chem 2008; 283:120-127. [DOI: 10.1074/jbc.m706997200] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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41
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Momose T, Ohshima C, Maeda M, Endo T. Structural basis of functional cooperation of Tim15/Zim17 with yeast mitochondrial Hsp70. EMBO Rep 2007; 8:664-70. [PMID: 17571076 PMCID: PMC1905897 DOI: 10.1038/sj.embor.7400990] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 04/26/2007] [Accepted: 04/26/2007] [Indexed: 11/08/2022] Open
Abstract
Mitochondrial heat-shock protein 70 (mtHsp70) and its partner proteins drive protein import into the matrix. Tim15/Zim17/Hep1 is a mtHsp70 partner protein on the matrix side of the inner mitochondrial membrane. We determined the nuclear magnetic resonance (NMR) structure of the core domain of Tim15. On the basis of the NMR structure, we created Tim15 mutants and tested their ability to complement the functional defects of Tim15 depletion and to suppress self-aggregation of mtHsp70 in vivo. A pair of basic residues, Arg 106 and His 107, conserved Asp 111 and flexible loop 133-137, and were important (Arg 106-His 107 pair and Asp 111) or partly important (the loop 133-137) for yeast cell growth, mitochondrial protein import and the suppression of mtHsp70 aggregation. Therefore, the function of Tim15 in yeast cell growth is well correlated with its ability to suppress mtHsp70 aggregation, although it is still unknown whether inhibition of mtHsp70 aggregation is the primary function of Tim15.
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Affiliation(s)
| | - Chié Ohshima
- Department of Chemistry, Graduate School of Science
| | | | - Toshiya Endo
- Department of Chemistry, Graduate School of Science
- Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation
- Institute for Advanced Research, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
- Tel: +81 52 789 2490; Fax: +81 52 789 2947; E-mail:
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42
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Bohnert M, Pfanner N, van der Laan M. A dynamic machinery for import of mitochondrial precursor proteins. FEBS Lett 2007; 581:2802-10. [PMID: 17376437 DOI: 10.1016/j.febslet.2007.03.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Accepted: 03/04/2007] [Indexed: 10/23/2022]
Abstract
Mitochondria contain approximately 1000 different proteins, which are located in four different compartments, outer membrane, inner membrane, intermembrane space and matrix. The vast majority of these proteins has to be imported from the cytosol. Therefore, sophisticated molecular machineries have evolved that mediate protein translocation across or insertion into mitochondrial membranes and subsequent assembly into multi-subunit complexes. While the initial entry of virtually all mitochondrial proteins is mediated by the general import pore of the outer membrane, at least four different downstream pathways are dedicated to import and assembly of proteins into a specific compartment.
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Affiliation(s)
- Maria Bohnert
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany
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43
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Szabadkai G, Bianchi K, Várnai P, De Stefani D, Wieckowski MR, Cavagna D, Nagy AI, Balla T, Rizzuto R. Chaperone-mediated coupling of endoplasmic reticulum and mitochondrial Ca2+ channels. ACTA ACUST UNITED AC 2007; 175:901-11. [PMID: 17178908 PMCID: PMC2064700 DOI: 10.1083/jcb.200608073] [Citation(s) in RCA: 1039] [Impact Index Per Article: 61.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The voltage-dependent anion channel (VDAC) of the outer mitochondrial membrane mediates metabolic flow, Ca(2+), and cell death signaling between the endoplasmic reticulum (ER) and mitochondrial networks. We demonstrate that VDAC1 is physically linked to the endoplasmic reticulum Ca(2+)-release channel inositol 1,4,5-trisphosphate receptor (IP(3)R) through the molecular chaperone glucose-regulated protein 75 (grp75). Functional interaction between the channels was shown by the recombinant expression of the ligand-binding domain of the IP(3)R on the ER or mitochondrial surface, which directly enhanced Ca(2+) accumulation in mitochondria. Knockdown of grp75 abolished the stimulatory effect, highlighting chaperone-mediated conformational coupling between the IP(3)R and the mitochondrial Ca(2+) uptake machinery. Because organelle Ca(2+) homeostasis influences fundamentally cellular functions and death signaling, the central location of grp75 may represent an important control point of cell fate and pathogenesis.
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Affiliation(s)
- György Szabadkai
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, Interdisciplinary Center for the Study of Inflammation, Emilia Romagna Laboratory for Genomics and Biotechnology, University of Ferrara, Ferrara 44100, Italy
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44
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Osorio C, Sullivan PM, He DN, Mace BE, Ervin JF, Strittmatter WJ, Alzate O. Mortalin is regulated by APOE in hippocampus of AD patients and by human APOE in TR mice. Neurobiol Aging 2006; 28:1853-62. [PMID: 17050040 DOI: 10.1016/j.neurobiolaging.2006.08.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Revised: 06/22/2006] [Accepted: 08/24/2006] [Indexed: 12/15/2022]
Abstract
Mortalin is a chaperone protein associated with cell survival, stress response, intracellular trafficking, control of cell proliferation, mitochondrial biogenesis, and cell fate determination. Human APOE targeted replacement (TR) mice have been used to elucidate the role of APOE4 in Alzheimer's disease (AD), since these animals express the APOE4 gene without the classical pathological signatures of AD. Using proteomics we found that mortalin isoforms are differentially expressed in the hippocampus of APOE4 TR mice compared with the APOE3 (control) TR mice. We also observed that these mortalin isoforms are differentially phosphorylated. Then we studied mortalin expression in patients with AD (genotypes APOE 3/3 and APOE 4/4) compared with patients without AD (genotype APOE 3/3). We observed that mortalin isoforms are also differentially expressed in the hippocampi of patients with AD, and that the expression of these mortalin isoforms is regulated by the APOE genotype. We propose that the differential regulation of mortalin in AD and by the APOE genotype is a cellular defense mechanism responding to increases in oxidative stress.
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Affiliation(s)
- Cristina Osorio
- Neuroproteomics Laboratory, Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
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45
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van der Laan M, Rissler M, Rehling P. Mitochondrial preprotein translocases as dynamic molecular machines. FEMS Yeast Res 2006; 6:849-61. [PMID: 16911507 DOI: 10.1111/j.1567-1364.2006.00134.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Proteomic studies have demonstrated that yeast mitochondria contain roughly 1000 different proteins. Only eight of these proteins are encoded by the mitochondrial genome and are synthesized on mitochondrial ribosomes. The remaining 99% of mitochondrial precursors are encoded within the nuclear genome and after their synthesis on cytosolic ribosomes must be imported into the organelle. Targeting of these proteins to mitochondria and their import into one of the four mitochondrial subcompartments--outer membrane, intermembrane space (IMS), inner membrane and matrix--requires various membrane-embedded protein translocases, as well as numerous chaperones and cochaperones in the aqueous compartments. During the last years, several novel protein components involved in the import and assembly of mitochondrial proteins have been identified. The picture that emerges from these exciting new findings is that of highly dynamic import machineries, rather than of regulated, but static protein complexes. In this review, we will give an overview on the recent progress in our understanding of mitochondrial protein import. We will focus on the presequence translocase of the inner mitochondrial membrane, the TIM23 complex and the presequence translocase-associated motor, the PAM complex. These two molecular machineries mediate the multistep import of preproteins with cleavable N-terminal signal sequences into the matrix or inner membrane of mitochondria.
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Affiliation(s)
- Martin van der Laan
- Institut für Biochemie und Molekularbiologie, Universität Freiburg, Freiburg, Germany
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46
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Gallas MR, Dienhart MK, Stuart RA, Long RM. Characterization of Mmp37p, a Saccharomyces cerevisiae mitochondrial matrix protein with a role in mitochondrial protein import. Mol Biol Cell 2006; 17:4051-62. [PMID: 16790493 PMCID: PMC1556384 DOI: 10.1091/mbc.e06-04-0366] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Many mitochondrial proteins are encoded by nuclear genes and after translation in the cytoplasm are imported via translocases in the outer and inner membranes, the TOM and TIM complexes, respectively. Here, we report the characterization of the mitochondrial protein, Mmp37p (YGR046w) and demonstrate its involvement in the process of protein import into mitochondria. Haploid cells deleted of MMP37 are viable but display a temperature-sensitive growth phenotype and are inviable in the absence of mitochondrial DNA. Mmp37p is located in the mitochondrial matrix where it is peripherally associated with the inner membrane. We show that Mmp37p has a role in the translocation of proteins across the mitochondrial inner membrane via the TIM23-PAM complex and further demonstrate that substrates containing a tightly folded domain in close proximity to their mitochondrial targeting sequences display a particular dependency on Mmp37p for mitochondrial import. Prior unfolding of the preprotein, or extension of the region between the targeting signal and the tightly folded domain, relieves their dependency for Mmp37p. Furthermore, evidence is presented to show that Mmp37 may affect the assembly state of the TIM23 complex. On the basis of these findings, we hypothesize that the presence of Mmp37p enhances the early stages of the TIM23 matrix import pathway to ensure engagement of incoming preproteins with the mtHsp70p/PAM complex, a step that is necessary to drive the unfolding and complete translocation of the preprotein into the matrix.
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Affiliation(s)
- Michelle R. Gallas
- *Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226; and
| | - Mary K. Dienhart
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201
| | - Rosemary A. Stuart
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201
| | - Roy M. Long
- *Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226; and
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47
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Stojanovski D, Rissler M, Pfanner N, Meisinger C. Mitochondrial morphology and protein import—A tight connection? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:414-21. [PMID: 16624427 DOI: 10.1016/j.bbamcr.2006.02.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 02/17/2006] [Accepted: 02/22/2006] [Indexed: 11/20/2022]
Abstract
Although the field of mitochondrial protein import and assembly may have initially been viewed as a completely distinct area of investigation to that of mitochondrial morphology and dynamics, recent findings have noted a clear influence on organelle morphology by perturbations in protein import pathways. This review aims to provide an overview of the mitochondrial import machinery in context of the recent link between translocation components and organelle structure, in addition to conferring the questions and challenges that have surfaced due to these observations.
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Affiliation(s)
- Diana Stojanovski
- Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany
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Prokisch H, Andreoli C, Ahting U, Heiss K, Ruepp A, Scharfe C, Meitinger T. MitoP2: the mitochondrial proteome database--now including mouse data. Nucleic Acids Res 2006; 34:D705-11. [PMID: 16381964 PMCID: PMC1347489 DOI: 10.1093/nar/gkj127] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The MitoP2 database () integrates information on mitochondrial proteins, their molecular functions and associated diseases. The central database features are manually annotated reference proteins localized or functionally associated with mitochondria supplied for yeast, human and mouse. MitoP2 enables (i) the identification of putative orthologous proteins between these species to study evolutionarily conserved functions and pathways; (ii) the integration of data from systematic genome-wide studies such as proteomics and deletion phenotype screening; (iii) the prediction of novel mitochondrial proteins using data integration and the assignment of evidence scores; and (iv) systematic searches that aim to find the genes that underlie common and rare mitochondrial diseases. The data and analysis files are referenced to data sources in PubMed and other online databases and can be easily downloaded. MitoP2 users can explore the relationship between mitochondrial dysfunctions and disease and utilize this information to conduct systems biology approaches on mitochondria.
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Affiliation(s)
- H Prokisch
- Institute of Human Genetics, Technical University of Munich, Munich, Germany.
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Lewandowska A, Gierszewska M, Marszalek J, Liberek K. Hsp78 chaperone functions in restoration of mitochondrial network following heat stress. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:141-51. [PMID: 16545993 DOI: 10.1016/j.bbamcr.2006.01.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Revised: 01/13/2006] [Accepted: 01/17/2006] [Indexed: 11/17/2022]
Abstract
Under physiological conditions mitochondria of yeast Saccharomyces cerevisiae form a branched tubular network, the continuity of which is maintained by balanced membrane fusion and fission processes. Here, we show using mitochondrial matrix targeted green fluorescent protein that exposure of cells to extreme heat shock led to dramatic changes in mitochondrial morphology, as tubular network disintegrated into several fragmented vesicles. Interestingly, this fragmentation did not affect mitochondrial ability to maintain the membrane potential. Cells subjected to recovery at physiological temperature were able to restore the mitochondrial network, as long as an active matrix chaperone, Hsp78, was present. Deletion of HSP78 gene did not affect fragmentation of mitochondria upon heat stress, but significantly inhibited ability to restore mitochondrial network. Changes of mitochondrial morphology correlated with aggregation of mitochondrial proteins. On the other hand, recovery of mitochondrial network correlated with disappearance of protein aggregates and reactivation of enzymatic activity of a model thermo-sensitive protein: mitochondrial DNA polymerase. Since protein disaggregation and refolding is mediated by Hsp78 chaperone collaborating with Hsp70 chaperone system, we postulate that effect of Hsp78 on mitochondrial morphology upon recovery after heat shock is mediated by its ability to restore activity of unknown protein(s) responsible for maintenance of mitochondrial morphology.
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Affiliation(s)
- Agnieszka Lewandowska
- Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland.
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von Janowsky B, Major T, Knapp K, Voos W. The disaggregation activity of the mitochondrial ClpB homolog Hsp78 maintains Hsp70 function during heat stress. J Mol Biol 2006; 357:793-807. [PMID: 16460754 DOI: 10.1016/j.jmb.2006.01.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 12/22/2005] [Accepted: 01/04/2006] [Indexed: 10/25/2022]
Abstract
Molecular chaperones are important components of mitochondrial protein biogenesis and are required to maintain the organellar function under normal and stress conditions. We addressed the functional role of the Hsp100/ClpB homolog Hsp78 during aggregation reactions and its functional cooperation with the main mitochondrial Hsp70, Ssc1, in mitochondria of the yeast Saccharomyces cerevisiae. By establishing an aggregation/disaggregation assay in intact mitochondria we demonstrated that Hsp78 is indispensable for the resolubilization of protein aggregates generated by heat stress under in vivo conditions. The ATP-dependent disaggregation activity of Hsp78 was capable of reversing the preprotein import defect of a destabilized mutant form of Ssc1. This role in disaggregation of Ssc1 is unique for Hsp78, since the recently identified, Hsp70-specific chaperone Zim17 had no effect on the resolubilization reaction. We observed only a minor effect of the second mitochondrial Hsp100 family member Mcx1 on protein disaggregation. A "holding" activity of the mitochondrial Hsp70 system was a prerequisite for a successful resolubilization of aggregated proteins. We conclude that the protective role of Hsp78 in thermotolerance is mainly based on maintaining the molecular chaperone Ssc1 in a soluble and functional state.
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Affiliation(s)
- Birgit von Janowsky
- Institut für Biochemie und Molekularbiologie, Hermann-Herder-Str. 7, Universität Freiburg, 79104 Freiburg, Germany
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