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Kim H, Park J, Roh SH. The structural basis of eukaryotic chaperonin TRiC/CCT: Action and folding. Mol Cells 2024; 47:100012. [PMID: 38280673 PMCID: PMC11004407 DOI: 10.1016/j.mocell.2024.100012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/26/2023] [Accepted: 12/26/2023] [Indexed: 01/29/2024] Open
Abstract
Accurate folding of proteins in living cells often requires the cooperative support of molecular chaperones. Eukaryotic group II chaperonin Tailless complex polypeptide 1-Ring Complex (TRiC) accomplishes this task by providing a folding chamber for the substrate that is regulated by an Adenosine triphosphate (ATP) hydrolysis-dependent cycle. Once delivered to and recognized by TRiC, the nascent substrate enters the folding chamber and undergoes folding and release in a stepwise manner. During the process, TRiC subunits and cochaperones such as prefoldin and phosducin-like proteins interact with the substrate to assist the overall folding process in a substrate-specific manner. Coevolution between the components is supposed to consult the binding specificity and ultimately expand the substrate repertoire assisted by the chaperone network. This review describes the TRiC chaperonin and the substrate folding process guided by the TRiC network in cooperation with cochaperones, specifically focusing on recent progress in structural analyses.
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Affiliation(s)
- Hyunmin Kim
- Department of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Republic of Korea
| | - Junsun Park
- Department of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Republic of Korea
| | - Soung-Hun Roh
- Department of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Republic of Korea.
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2
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van Zwam MC, Dhar A, Bosman W, van Straaten W, Weijers S, Seta E, Joosten B, van Haren J, Palani S, van den Dries K. IntAct: A nondisruptive internal tagging strategy to study the organization and function of actin isoforms. PLoS Biol 2024; 22:e3002551. [PMID: 38466773 PMCID: PMC10957077 DOI: 10.1371/journal.pbio.3002551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 03/21/2024] [Accepted: 02/16/2024] [Indexed: 03/13/2024] Open
Abstract
Mammals have 6 highly conserved actin isoforms with nonredundant biological functions. The molecular basis of isoform specificity, however, remains elusive due to a lack of tools. Here, we describe the development of IntAct, an internal tagging strategy to study actin isoforms in fixed and living cells. We identified a residue pair in β-actin that permits tag integration and used knock-in cell lines to demonstrate that IntAct β-actin expression and filament incorporation is indistinguishable from wild type. Furthermore, IntAct β-actin remains associated with common actin-binding proteins (ABPs) and can be targeted in living cells. We demonstrate the usability of IntAct for actin isoform investigations by showing that actin isoform-specific distribution is maintained in human cells. Lastly, we observed a variant-dependent incorporation of tagged actin variants into yeast actin patches, cables, and cytokinetic rings demonstrating cross species applicability. Together, our data indicate that IntAct is a versatile tool to study actin isoform localization, dynamics, and molecular interactions.
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Affiliation(s)
- Maxime C. van Zwam
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Anubhav Dhar
- Department of Biochemistry, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
| | - Willem Bosman
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Wendy van Straaten
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Suzanne Weijers
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Emiel Seta
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Ben Joosten
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | - Saravanan Palani
- Department of Biochemistry, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
| | - Koen van den Dries
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
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Park J, Kim H, Gestaut D, Lim S, Opoku-Nsiah KA, Leitner A, Frydman J, Roh SH. A structural vista of phosducin-like PhLP2A-chaperonin TRiC cooperation during the ATP-driven folding cycle. Nat Commun 2024; 15:1007. [PMID: 38307855 PMCID: PMC10837153 DOI: 10.1038/s41467-024-45242-x] [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: 03/16/2023] [Accepted: 01/16/2024] [Indexed: 02/04/2024] Open
Abstract
Proper cellular proteostasis, essential for viability, requires a network of chaperones and cochaperones. ATP-dependent chaperonin TRiC/CCT partners with cochaperones prefoldin (PFD) and phosducin-like proteins (PhLPs) to facilitate folding of essential eukaryotic proteins. Using cryoEM and biochemical analyses, we determine the ATP-driven cycle of TRiC-PFD-PhLP2A interaction. PhLP2A binds to open apo-TRiC through polyvalent domain-specific contacts with its chamber's equatorial and apical regions. PhLP2A N-terminal H3-domain binding to subunits CCT3/4 apical domains displace PFD from TRiC. ATP-induced TRiC closure rearranges the contacts of PhLP2A domains within the closed chamber. In the presence of substrate, actin and PhLP2A segregate into opposing chambers, each binding to positively charged inner surface residues from CCT1/3/6/8. Notably, actin induces a conformational change in PhLP2A, causing its N-terminal helices to extend across the inter-ring interface to directly contact a hydrophobic groove in actin. Our findings reveal an ATP-driven PhLP2A structural rearrangement cycle within the TRiC chamber to facilitate folding.
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Affiliation(s)
- Junsun Park
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Hyunmin Kim
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Daniel Gestaut
- Dept of Biology and Genetics, Stanford University, Stanford, CA, 94305, USA
| | - Seyeon Lim
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | | | - Alexander Leitner
- Institute of Molecular Systems Biology, Dept of Biology, ETH Zurich, Zurich, 8093, Switzerland
| | - Judith Frydman
- Dept of Biology and Genetics, Stanford University, Stanford, CA, 94305, USA.
| | - Soung-Hun Roh
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea.
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Park J, Kim H, Gestaut D, Lim S, Leitner A, Frydman J, Roh SH. A structural vista of phosducin-like PhLP2A-chaperonin TRiC cooperation during the ATP-driven folding cycle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.25.534239. [PMID: 37016670 PMCID: PMC10071816 DOI: 10.1101/2023.03.25.534239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Proper cellular proteostasis, essential for viability, requires a network of chaperones and cochaperones. ATP-dependent chaperonin TRiC/CCT partners with cochaperones prefoldin (PFD) and phosducin-like proteins (PhLPs) to facilitate the folding of essential eukaryotic proteins. Using cryoEM and biochemical analyses, we determine the ATP-driven cycle of TRiC-PFD-PhLP2A interaction. In the open TRiC state, PhLP2A binds to the chamber's equator while its N-terminal H3-domain binds to the apical domains of CCT3/4, thereby displacing PFD from TRiC. ATP-induced TRiC closure rearranges the contacts of PhLP2A domains within the closed chamber. In the presence of substrate, actin and PhLP2A segregate into opposing chambers, each binding to the positively charged inner surfaces formed by CCT1/3/6/8. Notably, actin induces a conformational change in PhLP2A, causing its N-terminal helices to extend across the inter-ring interface to directly contact a hydrophobic groove in actin. Our findings reveal an ATP-driven PhLP2A structural rearrangement cycle within the TRiC chamber to facilitate folding.
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Affiliation(s)
- Junsun Park
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Hyunmin Kim
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Daniel Gestaut
- Dept of Biology, Stanford University, Stanford, CA 94305, USA
| | - Seyeon Lim
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Alexander Leitner
- Institute of Molecular Systems Biology, Dept of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Judith Frydman
- Dept of Biology, Stanford University, Stanford, CA 94305, USA
- Dept of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Soung-Hun Roh
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
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Cancer type-specific alterations in actin genes: Worth a closer look? INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 360:133-184. [PMID: 33962749 DOI: 10.1016/bs.ircmb.2021.02.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Actins form a strongly conserved family of proteins that are central to the functioning of the actin cytoskeleton partaking in natural processes such as cell division, adhesion, contraction and migration. These processes, however, also occur during the various phases of cancer progression. Yet, surprisingly, alterations in the six human actin genes in cancer studies have received little attention and the focus was mostly on deregulated expression levels of actins and even more so of actin-binding or regulatory proteins. Starting from the early mutation work in the 1980s, we propose based on reviewing literature and data from patient cancer genomes that alterations in actin genes are different in distinct cancer subtypes, suggesting some specificity. These actin gene alterations include (missense) mutations, gene fusions and copy number alterations (deletions and amplifications) and we illustrate their occurrence for a limited number of examples including actin mutations in lymphoid cancers and nonmelanoma skin cancer and actin gene copy number alterations for breast, prostate and liver cancers. A challenge in the future will be to further sort out the specificity per actin gene, alteration type and cancer subtype. Even more challenging is (experimentally) distinguishing between cause and consequence: which alterations are passengers and which are involved in tumor progression of particular cancer subtypes?
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Witjes L, Van Troys M, Verhasselt B, Ampe C. Prevalence of Cytoplasmic Actin Mutations in Diffuse Large B-Cell Lymphoma and Multiple Myeloma: A Functional Assessment Based on Actin Three-Dimensional Structures. Int J Mol Sci 2020; 21:ijms21093093. [PMID: 32349449 PMCID: PMC7247664 DOI: 10.3390/ijms21093093] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 04/24/2020] [Accepted: 04/26/2020] [Indexed: 02/06/2023] Open
Abstract
Mutations in actins have been linked to several developmental diseases. Their occurrence across different cancers has, however, not been investigated. Using the cBioPortal database we show that human actins are infrequently mutated in patient samples of various cancers types. Nevertheless, ranking these studies by mutational frequency suggest that some have a higher percentage of patients with ACTB and ACTG1 mutations. Within studies on hematological cancers, mutations in ACTB and ACTG1 are associated with lymphoid cancers since none have currently been reported in myeloid cancers. Within the different types of lymphoid cancers ACTB mutations are most frequent in diffuse large B-cell lymphoma (DLBCL) and ACTG1 mutations in multiple myeloma. We mapped the ACTB and ACTG1 mutations found in these two cancer types on the 3D-structure of actin showing they are in regions important for actin polymer formation or binding to myosin. The potential effects of the mutations on actin properties imply that mutations in cytoplasmic actins deserve dedicated research in DLBCL and multiple myeloma.
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Affiliation(s)
- Laura Witjes
- Department of Biomolecular Medicine, Ghent University, Albert Baertsoenkaai 3, B-9000 Ghent, Belgium
- Department of Diagnostic Sciences, Ghent University Hospital, Ghent University, Corneel Heymanslaan 10, B-9000 Ghent, Belgium
| | - Marleen Van Troys
- Department of Biomolecular Medicine, Ghent University, Albert Baertsoenkaai 3, B-9000 Ghent, Belgium
| | - Bruno Verhasselt
- Department of Diagnostic Sciences, Ghent University Hospital, Ghent University, Corneel Heymanslaan 10, B-9000 Ghent, Belgium
| | - Christophe Ampe
- Department of Biomolecular Medicine, Ghent University, Albert Baertsoenkaai 3, B-9000 Ghent, Belgium
- Correspondence:
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Chen XM, Feng MJ, Shen CJ, He B, Du XF, Yu YB, Liu J, Chu HM. A novel approach to select differential pathways associated with hypertrophic cardiomyopathy based on gene co‑expression analysis. Mol Med Rep 2017; 16:773-777. [PMID: 28586052 PMCID: PMC5482204 DOI: 10.3892/mmr.2017.6667] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 03/20/2017] [Indexed: 02/02/2023] Open
Abstract
The present study was designed to develop a novel method for identifying significant pathways associated with human hypertrophic cardiomyopathy (HCM), based on gene co-expression analysis. The microarray dataset associated with HCM (E-GEOD-36961) was obtained from the European Molecular Biology Laboratory-European Bioinformatics Institute database. Informative pathways were selected based on the Reactome pathway database and screening treatments. An empirical Bayes method was utilized to construct co-expression networks for informative pathways, and a weight value was assigned to each pathway. Differential pathways were extracted based on weight threshold, which was calculated using a random model. In order to assess whether the co-expression method was feasible, it was compared with traditional pathway enrichment analysis of differentially expressed genes, which were identified using the significance analysis of microarrays package. A total of 1,074 informative pathways were screened out for subsequent investigations and their weight values were also obtained. According to the threshold of weight value of 0.01057, 447 differential pathways, including folding of actin by chaperonin containing T-complex protein 1 (CCT)/T-complex protein 1 ring complex (TRiC), purine ribonucleoside monophosphate biosynthesis and ubiquinol biosynthesis, were obtained. Compared with traditional pathway enrichment analysis, the number of pathways obtained from the co-expression approach was increased. The results of the present study demonstrated that this method may be useful to predict marker pathways for HCM. The pathways of folding of actin by CCT/TRiC and purine ribonucleoside monophosphate biosynthesis may provide evidence of the underlying molecular mechanisms of HCM, and offer novel therapeutic directions for HCM.
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Affiliation(s)
- Xiao-Min Chen
- Department of Cardiology, Ningbo First Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Ming-Jun Feng
- Department of Cardiology, Ningbo First Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Cai-Jie Shen
- Department of Cardiology, Ningbo Seventh Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Bin He
- Department of Cardiology, Ningbo First Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Xian-Feng Du
- Department of Cardiology, Ningbo First Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Yi-Bo Yu
- Department of Cardiology, Ningbo First Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Jing Liu
- Department of Cardiology, Ningbo First Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Hui-Min Chu
- Department of Cardiology, Ningbo First Hospital, Ningbo, Zhejiang 315000, P.R. China
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Lee JY, Duan L, Iverson TM, Dima RI. Exploring the role of topological frustration in actin refolding with molecular simulations. J Phys Chem B 2012; 116:1677-86. [PMID: 22243338 DOI: 10.1021/jp209340y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Actin plays crucial roles in the life of the cell while being notorious for its inability to reach a functional conformation without the help of assistant proteins. In eukaryotes, for example, the cytosolic chaperonin containing TCP-1 (CCT) and prefoldin (PFD) are required for actin folding assistance and prevention of protein aggregation in the crowded cellular environment. The folding of non-native actin is known to occur in a number of steps, but the reasons underlying its folding difficulty are unknown. Because a full, atomistic-level, investigation of the kinetics and thermodynamics of folding of such a large molecule is beyond computational reach, we focused our investigation on the role of topological frustration on the folding of actin. Namely, we studied the (re)folding of actin using simulations of a variant self-organized polymer model (SOP-DH) starting from a stretched state, leading to results that correlate well with experimentally driven conclusions and allowing us to make a number of testable predictions. Primarily, our simulations reveal that the successful refolding of the C-terminus end of actin occurs through a zipping process in which the α-helices wind up turn by turn upon formation of their native tertiary contacts. In turn, an early formation of the helical structure in this region of the chain has deleterious effects for actin's refolding fitness. Moreover, the C-terminus refolding is a very rare event in our simulations, in agreement with the large activation barrier predicted on the basis of experimental studies of actin unfolding in EDTA. We also discovered that subdomain 4 has a low refolding probability, which can help explain why many of the non-native actin target binding sites for CCT and PFD are located within this subdomain.
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Affiliation(s)
- Ji Young Lee
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, USA
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Popp D, Xu W, Narita A, Brzoska AJ, Skurray RA, Firth N, Goshdastider U, Maéda Y, Robinson RC, Schumacher MA. Structure and filament dynamics of the pSK41 actin-like ParM protein: implications for plasmid DNA segregation. J Biol Chem 2010; 285:10130-10140. [PMID: 20106979 DOI: 10.1074/jbc.m109.071613] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type II plasmid partition systems utilize ParM NTPases in coordination with a centromere-binding protein called ParR to mediate accurate DNA segregation, a process critical for plasmid retention. The Staphylococcus aureus pSK41 plasmid is a medically important plasmid that confers resistance to multiple antibiotics, disinfectants, and antiseptics. In the first step of partition, the pSK41 ParR binds its DNA centromere to form a superhelical partition complex that recruits ParM, which then mediates plasmid separation. pSK41 ParM is homologous to R1 ParM, a known actin homologue, suggesting that it may also form filaments to drive partition. To gain insight into the partition function of ParM, we examined its ability to form filaments and determined the crystal structure of apoParM to 1.95 A. The structure shows that pSK41 ParM belongs to the actin/Hsp70 superfamily. Unexpectedly, however, pSK41 ParM shows the strongest structural homology to the archaeal actin-like protein Thermoplasma acidophilum Ta0583, rather than its functional homologue, R1 ParM. Consistent with this divergence, we find that regions shown to be involved in R1 ParM filament formation are not important in formation of pSK41 ParM polymers. These data are also consonant with our finding that pSK41 ParM forms 1-start 10/4 helices very different from the 37/17 symmetry of R1 ParM. The polymerization kinetics of pSK41 ParM also differed from that of R1 ParM. These results indicate that type II NTPases utilize different polymeric structures to drive plasmid segregation.
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Affiliation(s)
- David Popp
- ERATO "Actin Filament Dynamics" Project, Japan Science and Technology Corporation, c/o RIKEN, Harima Institute at Spring 8, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos 138673, Singapore.
| | - Weijun Xu
- Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Akihiro Narita
- ERATO "Actin Filament Dynamics" Project, Japan Science and Technology Corporation, c/o RIKEN, Harima Institute at Spring 8, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Nagoya University Graduate School of Science, Structural Biology Research Center and Division of Biological Sciences, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Anthony J Brzoska
- School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Ronald A Skurray
- School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Neville Firth
- School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Umesh Goshdastider
- Nagoya University Graduate School of Science, Structural Biology Research Center and Division of Biological Sciences, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yuichiro Maéda
- ERATO "Actin Filament Dynamics" Project, Japan Science and Technology Corporation, c/o RIKEN, Harima Institute at Spring 8, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Nagoya University Graduate School of Science, Structural Biology Research Center and Division of Biological Sciences, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Robert C Robinson
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos 138673, Singapore
| | - Maria A Schumacher
- Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030.
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Vandamme D, Lambert E, Waterschoot D, Cognard C, Vandekerckhove J, Ampe C, Constantin B, Rommelaere H. alpha-Skeletal muscle actin nemaline myopathy mutants cause cell death in cultured muscle cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1259-71. [PMID: 19393268 DOI: 10.1016/j.bbamcr.2009.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 03/24/2009] [Accepted: 04/14/2009] [Indexed: 11/24/2022]
Abstract
Nemaline myopathy is a neuromuscular disorder, characterized by muscle weakness and hypotonia and is, in 20% of the cases, caused by mutations in the gene encoding alpha-skeletal muscle actin, ACTA1. It is a heterogeneous disease with various clinical phenotypes and severities. In patients the ultrastructure of muscle cells is often disturbed by nemaline rods and it is thought this is the cause for muscle weakness. To search for possible defects during muscle cell differentiation we expressed alpha-actin mutants in myoblasts and allowed these cells to differentiate into myotubes. Surprisingly, we observed two striking new phenotypes in differentiating myoblasts: rounding up of cells and bleb formation, two features reminiscent of apoptosis. Indeed expression of these mutants induced cell death with apoptotic features in muscle cell culture, using AIF and endonuclease G, in a caspase-independent but calpain-dependent pathway. This is the first report on a common cellular defect induced by NM causing actin mutants, independent of their biochemical phenotypes or rod and aggregate formation capacity. These data suggest that lack of type II fibers or atrophy observed in nemaline myopathy patients may be also due to an increased number of dying muscle cells.
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Affiliation(s)
- Drieke Vandamme
- Department of Biochemistry, Ghent University, A. Baertsoenkaai 3, B-9000, Gent, Belgium
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Vandamme D, Rommelaere H, Lambert E, Waterschoot D, Vandekerckhove J, Constantin B, Ampe C. α-Skeletal muscle actin mutants causing different congenital myopathies induce similar cytoskeletal defects in cell line cultures. ACTA ACUST UNITED AC 2009; 66:179-92. [DOI: 10.1002/cm.20340] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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12
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Phenotypes induced by NM causing alpha-skeletal muscle actin mutants in fibroblasts, Sol 8 myoblasts and myotubes. BMC Res Notes 2009; 2:40. [PMID: 19284548 PMCID: PMC2657152 DOI: 10.1186/1756-0500-2-40] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Accepted: 03/10/2009] [Indexed: 11/15/2022] Open
Abstract
Background Nemaline myopathy is a neuromuscular disorder characterized by the presence of nemaline bodies in patient muscles. 20% of the cases are associated with α-skeletal muscle actin mutations. We previously showed that actin mutations can cause four different biochemical phenotypes and that expression of NM associated actin mutants in fibroblasts, myoblasts and myotubes induces a range of cellular defects. Findings We conducted the same biochemical experiments for twelve new actin mutants associated with nemaline myopathy. We observed folding and polymerization defects. Immunostainings of these and eight other mutants in transfected cells revealed typical cellular defects such as nemaline rods or aggregates, decreased incorporation in F-actin structures, membrane blebbing, the formation of thickened actin fibres and cell membrane blebbing in myotubes. Conclusion Our results confirm that NM associated α-actin mutations induce a range of defects at the biochemical level as well as in cultured fibroblasts and muscle cells.
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Feng JJ, Marston S. Genotype–phenotype correlations in ACTA1 mutations that cause congenital myopathies. Neuromuscul Disord 2009; 19:6-16. [DOI: 10.1016/j.nmd.2008.09.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 09/08/2008] [Accepted: 09/09/2008] [Indexed: 12/01/2022]
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Neirynck K, Waterschoot D, Vandekerckhove J, Ampe C, Rommelaere H. Actin Interacts with CCT via Discrete Binding Sites: A Binding transition-release Model for CCT-Mediated Actin Folding. J Mol Biol 2006; 355:124-38. [PMID: 16300788 DOI: 10.1016/j.jmb.2005.10.051] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Revised: 09/29/2005] [Accepted: 10/18/2005] [Indexed: 11/28/2022]
Abstract
The chaperones prefoldin and the cytosolic chaperonin CCT-containing TCP-1 (CCT) guide the cytoskeletal protein actin to its native conformation. Performing an alanine scan of actin, we identified discrete recognition determinants for CCT interaction. Interestingly, one of these is similar and functional in the non-homologous protein Cdc20, suggesting that some of the binding information in the CCT target proteins is shared. The information in actin for recognition by CCT and for folding is different, as all but one of the mutants in the recognition determinants are folding-competent. In addition, some other actin mutants remain CCT-arrested and are not released in a native conformation, whereas others do fold but remain bound to CAP. Kinetic experiments provide evidence that CCT-mediated folding of non-native actin occurs in at least two steps, in which initially the recognition determinant 245-249 contacts CCT and the other determinants interact at later stages. Actin mutants that are CCT-arrested demonstrate that some regions neighbouring the recognition determinants are involved in modulating the correct folding transitions of actin on CCT, or its release from this chaperonin. Further, we found that the ATP binding of actin is not a prerequisite for its release, and we suggest that CAP may be involved in charging the nucleotide. Based on the kinetics of CCT binding and folding of actin and actin mutants, we propose a multi-step recognition-transition-release model. This also implies that the currently accepted notion of CCT-mediated actin folding is probably more complex.
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Affiliation(s)
- Katrien Neirynck
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. A. Baertsoenkaai 3, 9000 Gent, Belgium
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Vang S, Corydon TJ, Børglum AD, Scott MD, Frydman J, Mogensen J, Gregersen N, Bross P. Actin mutations in hypertrophic and dilated cardiomyopathy cause inefficient protein folding and perturbed filament formation. FEBS J 2005; 272:2037-49. [PMID: 15819894 DOI: 10.1111/j.1742-4658.2005.04630.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are the most common hereditary cardiac conditions. Both are frequent causes of sudden death and are often associated with an adverse disease course. Alpha-cardiac actin is one of the disease genes where different missense mutations have been found to cause either HCM or DCM. We have tested the hypothesis that the protein-folding pathway plays a role in disease development for two actin variants associated with DCM and six associated with HCM. Based on a cell-free coupled translation assay the actin variants could be graded by their tendency to associate with the chaperonin TCP-1 ring complex/chaperonin containing TCP-1 (TRiC/CCT) as well as their propensity to acquire their native conformation. Some variant proteins are completely stalled in a complex with TRiC and fail to fold into mature globular actin and some appear to fold as efficiently as the wild-type protein. A fraction of the translated polypeptide became ubiquitinated and detergent insoluble. Variant actin proteins overexpressed in mammalian cell lines fail to incorporate into actin filaments in a manner correlating with the degree of misfolding observed in the cell-free assay; ranging from incorporation comparable to wild-type actin to little or no incorporation. We propose that effects of mutations on folding and fiber assembly may play a role in the molecular disease mechanism.
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Affiliation(s)
- Søren Vang
- Research Unit for Molecular Medicine, Aarhus University Hospital and Faculty of Health Sciences, Denmark.
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16
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Costa CF, Rommelaere H, Waterschoot D, Sethi KK, Nowak KJ, Laing NG, Ampe C, Machesky LM. Myopathy mutations in alpha-skeletal-muscle actin cause a range of molecular defects. J Cell Sci 2005; 117:3367-77. [PMID: 15226407 DOI: 10.1242/jcs.01172] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutations in the gene encoding alpha-skeletal-muscle actin, ACTA1, cause congenital myopathies of various phenotypes that have been studied since their discovery in 1999. Although much is now known about the clinical aspects of myopathies resulting from over 60 different ACTA1 mutations, we have very little evidence for how mutations alter the behavior of the actin protein and thus lead to disease. We used a combination of biochemical and cell biological analysis to classify 19 myopathy mutants and found a range of defects in the actin. Using in vitro expression systems, we probed actin folding and actin's capacity to interact with actin-binding proteins and polymerization. Only two mutants failed to fold; these represent recessive alleles, causing severe myopathy, indicating that patients produce nonfunctional actin. Four other mutants bound tightly to cyclase-associated protein, indicating a possible instability in the nucleotide-binding pocket, and formed rods and aggregates in cells. Eleven mutants showed defects in the ability to co-polymerize with wild-type actin. Some of these could incorporate into normal actin structures in NIH 3T3 fibroblasts, but two of the three tested also formed aggregates. Four mutants showed no defect in vitro but two of these formed aggregates in cells, indicating functional defects that we have not yet tested for. Overall, we found a range of defects and behaviors of the mutants in vitro and in cultured cells, paralleling the complexity of actin-based muscle myopathy phenotypes.
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Affiliation(s)
- Céline F Costa
- School of Biosciences, Division of Molecular Cell Biology, University of Birmingham, B15 2TT, UK
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17
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Muhlrad A, Kudryashov D, Michael Peyser Y, Bobkov AA, Almo SC, Reisler E. Cofilin induced conformational changes in F-actin expose subdomain 2 to proteolysis. J Mol Biol 2004; 342:1559-67. [PMID: 15364581 DOI: 10.1016/j.jmb.2004.08.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2004] [Revised: 08/03/2004] [Accepted: 08/05/2004] [Indexed: 10/26/2022]
Abstract
Cofilin/ADF affects strongly the structure of actin filaments and especially the intermolecular contacts of the DNase I binding loop (D-loop) in subdomain 2. In G-actin, the D-loop is cleaved by subtilisin between Met47 and Gly48, while in F-actin this cleavage is inhibited. Here, we report that yeast cofilin, which is resistant to both subtilisin and trypsin, accelerates greatly the rate of subtilisin cleavage of this loop in F-actin at pH 6.8 and at pH 8.0. Similarly, cofilin accelerates strongly the tryptic cleavage in F-actin of loop 60-69 in subdomain 2, at Arg62 and Lys68. The acceleration of the loops' proteolysis cannot be attributed to an increased treadmilling of F-actin for the following reasons: (i) the rate of subtilisin cleavage is independent of pH between pH 6.8 and 8.0, unlike F-actin depolymerization, which is pH-dependent; (ii) at high concentrations of protease the cleavage rate of F-actin in the presence of cofilin is faster than the rate of monomer dissociation from the pointed end of TRC-labeled F-actin, which limits the rate of treadmilling; and (iii) cofilin also accelerates the rate of subtilisin cleavage of F-actin in which the treadmilling is blocked by interprotomer cross-linking of the D-loop to the C terminus on an adjacent protomer. This suggests a substantial flexibility of the D-loop in the cross-linked F-actin. The increased cleavage rates of the D-loop and loop 60-69 reveal extensive exposure of subdomain 2 in F-actin to proteolytic enzymes by cofilin.
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Affiliation(s)
- Andras Muhlrad
- Institute of Dental Sciences, School of Dental Medicine, Hebrew University of Jerusalem, P.O. Box 12272, Jerusalem 91120, Israel.
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18
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Rommelaere H, Waterschoot D, Neirynck K, Vandekerckhove J, Ampe C. A method for rapidly screening functionality of actin mutants and tagged actins. Biol Proced Online 2004; 6:235-249. [PMID: 15514698 PMCID: PMC524212 DOI: 10.1251/bpo94] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2004] [Revised: 09/23/2004] [Accepted: 10/01/2004] [Indexed: 11/26/2022] Open
Abstract
Recombinant production and biochemical analysis of actin mutants has been hampered by the fact that actin has an absolute requirement for the eukaryotic chaperone CCT to reach its native state. We therefore have developed a method to rapidly screen the folding capacity and functionality of actin variants, by combining in vitro expression of labelled actin with analysis on native gels, band shift assays or copolymerization tests. Additionally, we monitor, using immuno-fluorescence, incorporation of actin variants in cytoskeletal structures in transfected cells. We illustrate the method by two examples. In one we show that tagged versions of actin do not always behave native-like and in the other we study some of the molecular defects of three beta-actin mutants that have been associated with diseases.
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Affiliation(s)
- Heidi Rommelaere
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
| | - Davy Waterschoot
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
| | - Katrien Neirynck
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
| | - Joël Vandekerckhove
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
| | - Christophe Ampe
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
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19
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Mattila PK, Quintero-Monzon O, Kugler J, Moseley JB, Almo SC, Lappalainen P, Goode BL. A high-affinity interaction with ADP-actin monomers underlies the mechanism and in vivo function of Srv2/cyclase-associated protein. Mol Biol Cell 2004; 15:5158-71. [PMID: 15356265 PMCID: PMC524793 DOI: 10.1091/mbc.e04-06-0444] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cyclase-associated protein (CAP), also called Srv2 in Saccharomyces cerevisiae, is a conserved actin monomer-binding protein that promotes cofilin-dependent actin turnover in vitro and in vivo. However, little is known about the mechanism underlying this function. Here, we show that S. cerevisiae CAP binds with strong preference to ADP-G-actin (Kd 0.02 microM) compared with ATP-G-actin (Kd 1.9 microM) and competes directly with cofilin for binding ADP-G-actin. Further, CAP blocks actin monomer addition specifically to barbed ends of filaments, in contrast to profilin, which blocks monomer addition to pointed ends of filaments. The actin-binding domain of CAP is more extensive than previously suggested and includes a recently solved beta-sheet structure in the C-terminus of CAP and adjacent sequences. Using site-directed mutagenesis, we define evolutionarily conserved residues that mediate binding to ADP-G-actin and demonstrate that these activities are required for CAP function in vivo in directing actin organization and polarized cell growth. Together, our data suggest that in vivo CAP competes with cofilin for binding ADP-actin monomers, allows rapid nucleotide exchange to occur on actin, and then because of its 100-fold weaker binding affinity for ATP-actin compared with ADP-actin, allows other cellular factors such as profilin to take the handoff of ATP-actin and facilitate barbed end assembly.
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Affiliation(s)
- Pieta K Mattila
- Program in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
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20
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Moraczewska J, Gruszczynska-Biegala J, Redowicz MJ, Khaitlina SY, Strzelecka-Golaszewska H. The DNase-I binding loop of actin may play a role in the regulation of actin-myosin interaction by tropomyosin/troponin. J Biol Chem 2004; 279:31197-204. [PMID: 15159400 DOI: 10.1074/jbc.m400794200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Various lines of evidence suggest that communication between tropomyosin and myosin in the regulation of vertebrate-striated muscle contraction involves yet unknown changes in actin conformation. Possible participation of loop 38-52 in this communication has recently been questioned based on unimpaired Ca(2+) regulation of myosin interaction, in the presence of the tropomyosin-troponin complex, with actin cleaved by subtilisin between Met(47) and Gly(48). We have compared the effects of actin cleavage by subtilisin and by protease ECP32, between Gly(42) and Val(43), on its interaction with myosin S1 in the presence and absence of tropomyosin or tropomyosin-troponin. Both individual modifications reduced activation of S1 ATPase by actin to a similar extent. The effect of ECP cleavage, but not of subtilisin cleavage, was partially reversed by stabilization of interprotomer contacts with phalloidin, indicating different pathways of signal transmission from the N- and C-terminal parts of loop 38-52 to myosin binding sites. ECP cleavage diminished the affinity to tropomyosin and reduced its inhibition of acto-S1 ATPase at low S1 concentrations, but increased the tropomyosin-mediated cooperative enhancement of the ATPase by S1 binding to actin. These effects were reversed by phalloidin. Subtilisin-cleaved actin more closely resembled unmodified actin than the ECP-modified actin. Limited proteolysis of the modified and unmodified F-actins revealed an allosteric effect of ECP cleavage on the conformation of the actin subdomain 4 region that is presumably involved in tropomyosin binding. Our results point to a possible role of the N-terminal part of loop 38-52 of actin in communication between tropomyosin and myosin through changes in actin structure.
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Affiliation(s)
- Joanna Moraczewska
- Department of Muscle Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland
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21
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Sparrow JC. Exploring actin five steps at a time. Structure 2003; 11:1196-7. [PMID: 14527387 DOI: 10.1016/j.str.2003.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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