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Barry ME, Rynkiewicz MJ, Pavadai E, Viana A, Lehman W, Moore JR. Glutamate 139 of tropomyosin is critical for cardiac thin filament blocked-state stabilization. J Mol Cell Cardiol 2024; 188:30-37. [PMID: 38266978 DOI: 10.1016/j.yjmcc.2024.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 12/14/2023] [Accepted: 01/20/2024] [Indexed: 01/26/2024]
Abstract
The cardiac thin filament proteins troponin and tropomyosin control actomyosin formation and thus cardiac contractility. Calcium binding to troponin changes tropomyosin position along the thin filament, allowing myosin head binding to actin required for heart muscle contraction. The thin filament regulatory proteins are hot spots for genetic mutations causing heart muscle dysfunction. While much of the thin filament structure has been characterized, critical regions of troponin and tropomyosin involved in triggering conformational changes remain unresolved. A poorly resolved region, helix-4 (H4) of troponin I, is thought to stabilize tropomyosin in a position on actin that blocks actomyosin interactions at low calcium concentrations during muscle relaxation. We have proposed that contact between glutamate 139 on tropomyosin and positively charged residues on H4 leads to blocking-state stabilization. In this study, we attempted to disrupt these interactions by replacing E139 with lysine (E139K) to define the importance of this residue in thin filament regulation. Comparison of mutant and wild-type tropomyosin was carried out using in-vitro motility assays, actin co-sedimentation, and molecular dynamics simulations to determine perturbations in troponin-tropomyosin function caused by the tropomyosin mutation. Motility assays revealed that mutant thin filaments moved at higher velocity at low calcium with increased calcium sensitivity demonstrating that tropomyosin residue 139 is vital for proper tropomyosin-mediated inhibition during relaxation. Similarly, molecular dynamic simulations revealed a mutation-induced decrease in interaction energy between tropomyosin-E139K and troponin I (R170 and K174). These results suggest that salt-bridge stabilization of tropomyosin position by troponin IH4 is essential to prevent actomyosin interactions during cardiac muscle relaxation.
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Affiliation(s)
- Meaghan E Barry
- Department of Biological Sciences, University of Massachusetts Lowell, One University Ave, Lowell, MA 01854, United States of America
| | - Michael J Rynkiewicz
- Department of Pharmacology, Physiology & Biophysics, Boston University Chobanian and Avedisan School of Medicine, 700 Albany Street, W-408E, Boston, MA 02118, United States of America
| | - Elumalai Pavadai
- Department of Pharmacology, Physiology & Biophysics, Boston University Chobanian and Avedisan School of Medicine, 700 Albany Street, W-408E, Boston, MA 02118, United States of America
| | - Alex Viana
- Department of Biological Sciences, University of Massachusetts Lowell, One University Ave, Lowell, MA 01854, United States of America
| | - William Lehman
- Department of Pharmacology, Physiology & Biophysics, Boston University Chobanian and Avedisan School of Medicine, 700 Albany Street, W-408E, Boston, MA 02118, United States of America
| | - Jeffrey R Moore
- Department of Biological Sciences, University of Massachusetts Lowell, One University Ave, Lowell, MA 01854, United States of America.
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2
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Küçükdogru R, Franz P, Worch R, Robaszkiewicz K, Siatkowska M, Tsiavaliaris G, Moraczewska J. Mechanochemical consequences of myopathy-linked mutations in Tpm2.2 on striated muscle contractility. FASEB J 2024; 38:e23400. [PMID: 38156416 DOI: 10.1096/fj.202301604r] [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: 08/07/2023] [Revised: 12/04/2023] [Accepted: 12/18/2023] [Indexed: 12/30/2023]
Abstract
Tropomyosin (Tpm) is an actin-binding protein central to muscle contraction regulation. The Tpm sequence consists of periodic repeats corresponding to seven actin-binding sites, further divided in two functionally distinct halves. To clarify the importance of the first and second halves of the actin-binding periods in regulating the interaction of myosin with actin, we introduced hypercontractile mutations D20H, E181K located in the N-terminal halves of periods 1 and 5 and hypocontractile mutations E41K, N202K located in the C-terminal halves of periods 1 and 5 of the skeletal muscle Tpm isoform Tpm2.2. Wild-type and mutant Tpms displayed similar actin-binding properties, however, as revealed by FRET experiments, the hypercontractile mutations affected the binding geometry and orientation of Tpm2.2 on actin, causing a stimulation of myosin motor performance. Contrary, the hypocontractile mutations led to an inhibition of both, actin activation of the myosin ATPase and motor activity, that was more pronounced than with wild-type Tpm2.2. Single ATP turnover kinetic experiments indicate that the introduced mutations have opposite effects on product release kinetics. While the hypercontractile Tpm2.2 mutants accelerated product release, the hypocontractile mutants decelerated product release from myosin, thus having either an activating or inhibitory influence on myosin motor performance, which agrees with the muscle disease phenotypes caused by these mutations.
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Affiliation(s)
- Recep Küçükdogru
- Department of Biochemistry and Cell Biology, Faculty of Biological Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Peter Franz
- Cellular Biophysics, Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Remigiusz Worch
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Katarzyna Robaszkiewicz
- Department of Biochemistry and Cell Biology, Faculty of Biological Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Małgorzata Siatkowska
- Department of Biochemistry and Cell Biology, Faculty of Biological Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Georgios Tsiavaliaris
- Cellular Biophysics, Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Biological Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
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Zhang Y, Lu Y, Yu M, Wang J, Du X, Zhao D, Pian H, He Z, Wu G, Li S, Wang S, Yu D. Transcriptome Profiling Identifies Differentially Expressed Genes in Skeletal Muscle Development in Native Chinese Ducks. Genes (Basel) 2023; 15:52. [PMID: 38254942 PMCID: PMC10815232 DOI: 10.3390/genes15010052] [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: 11/02/2023] [Revised: 12/20/2023] [Accepted: 12/27/2023] [Indexed: 01/24/2024] Open
Abstract
China boasts a rich diversity of indigenous duck species, some of which exhibit desirable economic traits. Here, we generated transcriptome sequencing datasets of breast muscle tissue samples from 1D of four groups: Pekin duck pure breeding group (P), Jinling White duck breeding group (J), P ♂ × J ♀ orthogonal group (PJ) and J ♂ × P ♀ reciprocal-cross group (JP) (n = 3), chosen based on the distinctive characteristics of duck muscle development during the embryonic period. We identified 5053 differentially expressed genes (DEGs) among the four groups. Network prediction analysis showed that ribosome and oxidative phosphorylation-related genes were the most enriched, and muscular protein-related genes were found in the 14-day-old embryonic group. We found that previously characterized functional genes, such as FN1, AGRN, ADNAMST3, APOB and FGF9, were potentially involved in muscle development in 14-day-old embryos. Functional enrichment analysis suggested that genes that participated in molecular function and cell component and key signaling pathways (e.g., hippo, ribosome, oxidative phosphorylation) were significantly enriched in the development of skeletal muscle at 14 days of embryonic age. These results indicate a possible role of muscle metabolism and myoglobin synthesis in skeletal muscle development in both duck parents and hybrids.
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Affiliation(s)
- Yuchen Zhang
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China; (Y.Z.)
| | - Yinglin Lu
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China; (Y.Z.)
| | - Minli Yu
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China; (Y.Z.)
| | - Jin Wang
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China; (Y.Z.)
| | - Xubin Du
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China; (Y.Z.)
| | - Dong Zhao
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China; (Y.Z.)
- School of Animal Medical, Jiangsu Agri-Animal Husbandry Vocational College, Taizhou 225300, China
| | - Huifang Pian
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China; (Y.Z.)
| | - Zongliang He
- Nanjing Academy of Animal Husbandry and Poultry, Nanjing 210095, China
| | - Guansuo Wu
- Nanjing Academy of Animal Husbandry and Poultry, Nanjing 210095, China
| | - Shiwei Li
- College of Animal Science, Xizang Agricultural and Animal Husbandry University, Linzhi 860000, China
| | - Sike Wang
- College of Animal Science, Xizang Agricultural and Animal Husbandry University, Linzhi 860000, China
| | - Debing Yu
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China; (Y.Z.)
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Lambert MR, Gussoni E. Tropomyosin 3 (TPM3) function in skeletal muscle and in myopathy. Skelet Muscle 2023; 13:18. [PMID: 37936227 PMCID: PMC10629095 DOI: 10.1186/s13395-023-00327-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: 08/11/2023] [Accepted: 10/10/2023] [Indexed: 11/09/2023] Open
Abstract
The tropomyosin genes (TPM1-4) contribute to the functional diversity of skeletal muscle fibers. Since its discovery in 1988, the TPM3 gene has been recognized as an indispensable regulator of muscle contraction in slow muscle fibers. Recent advances suggest that TPM3 isoforms hold more extensive functions during skeletal muscle development and in postnatal muscle. Additionally, mutations in the TPM3 gene have been associated with the features of congenital myopathies. The use of different in vitro and in vivo model systems has leveraged the discovery of several disease mechanisms associated with TPM3-related myopathy. Yet, the precise mechanisms by which TPM3 mutations lead to muscle dysfunction remain unclear. This review consolidates over three decades of research about the role of TPM3 in skeletal muscle. Overall, the progress made has led to a better understanding of the phenotypic spectrum in patients affected by mutations in this gene. The comprehensive body of work generated over these decades has also laid robust groundwork for capturing the multiple functions this protein plays in muscle fibers.
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Affiliation(s)
- Matthias R Lambert
- Division of Genetics and Genomics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA, 02115, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
| | - Emanuela Gussoni
- Division of Genetics and Genomics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA, 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
- The Stem Cell Program, Boston Children's Hospital, Boston, MA, 02115, USA
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5
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Karpicheva OE. Hallmark Features of the Tropomyosin
Regulatory Function in Several Variants of Congenital Myopathy. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021030133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Thin filament dysfunctions caused by mutations in tropomyosin Tpm3.12 and Tpm1.1. J Muscle Res Cell Motil 2019; 41:39-53. [PMID: 31270709 PMCID: PMC7109180 DOI: 10.1007/s10974-019-09532-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 06/26/2019] [Indexed: 12/14/2022]
Abstract
Tropomyosin is the major regulator of the thin filament. In striated muscle its function is to bind troponin complex and control the access of myosin heads to actin in a Ca2+-dependent manner. It also participates in the maintenance of thin filament length by regulation of tropomodulin and leiomodin, the pointed end-binding proteins. Because the size of the overlap between actin and myosin filaments affects the number of myosin heads which interact with actin, the filament length is one of the determinants of force development. Numerous point mutations in genes encoding tropomyosin lead to single amino acid substitutions along the entire length of the coiled coil that are associated with various types of cardiomyopathy and skeletal muscle disease. Specific regions of tropomyosin interact with different binding partners; therefore, the mutations affect diverse tropomyosin functions. In this review, results of studies on mutations in the genes TPM1 and TPM3, encoding Tpm1.1 and Tpm3.12, are described. The paper is particularly focused on mutation-dependent alterations in the mechanisms of actin-myosin interactions and dynamics of the thin filament at the pointed end.
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Moraczewska J, Robaszkiewicz K, Śliwinska M, Czajkowska M, Ly T, Kostyukova A, Wen H, Zheng W. Congenital myopathy-related mutations in tropomyosin disrupt regulatory function through altered actin affinity and tropomodulin binding. FEBS J 2019; 286:1877-1893. [PMID: 30768849 PMCID: PMC7202179 DOI: 10.1111/febs.14787] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 12/28/2018] [Accepted: 02/13/2019] [Indexed: 11/28/2022]
Abstract
Tropomyosin (Tpm) binds along actin filaments and regulates myosin binding to control muscle contraction. Tropomodulin binds to the pointed end of a filament and regulates actin dynamics, which maintains the length of a thin filament. To define the structural determinants of these Tpm functions, we examined the effects of two congenital myopathy mutations, A4V and R91C, in the Tpm gene, TPM3, which encodes the Tpm3.12 isoform, specific for slow-twitch muscle fibers. Mutation A4V is located in the tropomodulin-binding, N-terminal region of Tpm3.12. R91C is located in the actin-binding period 3 and directly interacts with actin. The A4V and R91C mutations resulted in a 2.5-fold reduced affinity of Tpm3.12 homodimers for F-actin in the absence and presence of troponin, and a two-fold decrease in actomyosin ATPase activation in the presence of Ca2+ . Actomyosin ATPase inhibition in the absence of Ca2+ was not affected. The Ca2+ sensitivity of ATPase activity was decreased by R91C, but not by A4V. In vitro, R91C altered the ability of tropomodulin 1 (Tmod1) to inhibit actin polymerization at the pointed end of the filaments, which correlated with the reduced affinity of Tpm3.12-R91C for Tmod1. Molecular dynamics simulations of Tpm3.12 in complex with F-actin suggested that both mutations reduce the affinity of Tpm3.12 for F-actin binding by perturbing the van der Waals energy, which may be attributable to two different molecular mechanisms-a reduced flexibility of Tpm3.12-R91C and an increased flexibility of Tpm3.12-A4V.
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Affiliation(s)
- Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Katarzyna Robaszkiewicz
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Małgorzata Śliwinska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Marta Czajkowska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Thu Ly
- Voiland School of Chemical Engineering and Bioengineering, University of Washington, Pullman, WA, USA
| | - Alla Kostyukova
- Voiland School of Chemical Engineering and Bioengineering, University of Washington, Pullman, WA, USA
| | - Han Wen
- Department of Physics, University at Buffalo, SUNY, NY, USA
| | - Wenjun Zheng
- Department of Physics, University at Buffalo, SUNY, NY, USA
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8
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Śliwinska M, Robaszkiewicz K, Czajkowska M, Zheng W, Moraczewska J. Functional effects of substitutions I92T and V95A in actin-binding period 3 of tropomyosin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1866:558-568. [PMID: 29496559 DOI: 10.1016/j.bbapap.2018.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 02/12/2018] [Accepted: 02/23/2018] [Indexed: 01/10/2023]
Affiliation(s)
- Małgorzata Śliwinska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Ks. J. Poniatowskiego 12 Str., 85-671 Bydgoszcz, Poland
| | - Katarzyna Robaszkiewicz
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Ks. J. Poniatowskiego 12 Str., 85-671 Bydgoszcz, Poland
| | - Marta Czajkowska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Ks. J. Poniatowskiego 12 Str., 85-671 Bydgoszcz, Poland
| | - Wenjun Zheng
- Department of Physics, University at Buffalo, SUNY, Buffalo, NY 14260, United States
| | - Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Ks. J. Poniatowskiego 12 Str., 85-671 Bydgoszcz, Poland.
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9
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Pelham JF, Mosier AE, Hurley JM. Characterizing Time-of-Day Conformational Changes in the Intrinsically Disordered Proteins of the Circadian Clock. Methods Enzymol 2018; 611:503-529. [DOI: 10.1016/bs.mie.2018.08.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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10
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Karpicheva OE, Sirenko VV, Rysev NA, Simonyan AO, Borys D, Moraczewska J, Borovikov YS. Deviations in conformational rearrangements of thin filaments and myosin caused by the Ala155Thr substitution in hydrophobic core of tropomyosin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1790-1799. [PMID: 28939420 DOI: 10.1016/j.bbapap.2017.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 09/14/2017] [Accepted: 09/18/2017] [Indexed: 12/28/2022]
Abstract
Effects of the Ala155Thr substitution in hydrophobic core of tropomyosin Tpm1.1 on conformational rearrangements of the components of the contractile system (Tpm1.1, actin and myosin heads) were studied by polarized fluorimetry technique at different stages of the actomyosin ATPase cycle. The proteins were labelled by fluorescent probes and incorporated into ghost muscle fibres. The substitution violated the blocked and closed states of thin filaments stimulating abnormal displacement of tropomyosin to the inner domains of actin, switching actin on and increasing the relative number of the myosin heads in strong-binding state. Furthermore, the mutant tropomyosin disrupted the major function of troponin to alter the distribution of the different functional states of thin filaments. At low Ca2+ troponin did not effectively switch thin filament off and the myosin head lost the ability to drive the spatial arrangement of the mutant tropomyosin. The information about tropomyosin flexibility obtained from the fluorescent probes at Cys190 indicates that this tropomyosin is generally more rigid, that obviously prevents tropomyosin to bend and adopt the appropriate conformation required for proper regulation.
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Affiliation(s)
- Olga E Karpicheva
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia
| | - Vladimir V Sirenko
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia
| | - Nikita A Rysev
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia
| | - Armen O Simonyan
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia; Saint Petersburg State University, 7/9 Universitetskaya nab, 199034 St Petersburg, Russia
| | - Danuta Borys
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, 12 Ks. J. Poniatowski St., 85-671 Bydgoszcz, Poland
| | - Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, 12 Ks. J. Poniatowski St., 85-671 Bydgoszcz, Poland
| | - Yurii S Borovikov
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia.
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11
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Minde D, Dunker AK, Lilley KS. Time, space, and disorder in the expanding proteome universe. Proteomics 2017; 17:1600399. [PMID: 28145059 PMCID: PMC5573936 DOI: 10.1002/pmic.201600399] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/16/2017] [Accepted: 01/25/2017] [Indexed: 12/31/2022]
Abstract
Proteins are highly dynamic entities. Their myriad functions require specific structures, but proteins' dynamic nature ranges all the way from the local mobility of their amino acid constituents to mobility within and well beyond single cells. A truly comprehensive view of the dynamic structural proteome includes: (i) alternative sequences, (ii) alternative conformations, (iii) alternative interactions with a range of biomolecules, (iv) cellular localizations, (v) alternative behaviors in different cell types. While these aspects have traditionally been explored one protein at a time, we highlight recently emerging global approaches that accelerate comprehensive insights into these facets of the dynamic nature of protein structure. Computational tools that integrate and expand on multiple orthogonal data types promise to enable the transition from a disjointed list of static snapshots to a structurally explicit understanding of the dynamics of cellular mechanisms.
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Affiliation(s)
- David‐Paul Minde
- Cambridge Systems Biology CentreUniversity of CambridgeCambridgeUK
- Cambridge Centre for ProteomicsDepartment of BiochemistryUniversity of CambridgeCambridgeUK
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - A. Keith Dunker
- Center for Computational Biology and BioinformaticsIndiana University School of MedicineIndianapolisINUSA
| | - Kathryn S. Lilley
- Cambridge Systems Biology CentreUniversity of CambridgeCambridgeUK
- Cambridge Centre for ProteomicsDepartment of BiochemistryUniversity of CambridgeCambridgeUK
- Department of BiochemistryUniversity of CambridgeCambridgeUK
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12
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Yuen M, Cooper ST, Marston SB, Nowak KJ, McNamara E, Mokbel N, Ilkovski B, Ravenscroft G, Rendu J, de Winter JM, Klinge L, Beggs AH, North KN, Ottenheijm CAC, Clarke NF. Muscle weakness in TPM3-myopathy is due to reduced Ca2+-sensitivity and impaired acto-myosin cross-bridge cycling in slow fibres. Hum Mol Genet 2015; 24:6278-92. [PMID: 26307083 DOI: 10.1093/hmg/ddv334] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/10/2015] [Indexed: 11/13/2022] Open
Abstract
Dominant mutations in TPM3, encoding α-tropomyosinslow, cause a congenital myopathy characterized by generalized muscle weakness. Here, we used a multidisciplinary approach to investigate the mechanism of muscle dysfunction in 12 TPM3-myopathy patients. We confirm that slow myofibre hypotrophy is a diagnostic hallmark of TPM3-myopathy, and is commonly accompanied by skewing of fibre-type ratios (either slow or fast fibre predominance). Patient muscle contained normal ratios of the three tropomyosin isoforms and normal fibre-type expression of myosins and troponins. Using 2D-PAGE, we demonstrate that mutant α-tropomyosinslow was expressed, suggesting muscle dysfunction is due to a dominant-negative effect of mutant protein on muscle contraction. Molecular modelling suggested mutant α-tropomyosinslow likely impacts actin-tropomyosin interactions and, indeed, co-sedimentation assays showed reduced binding of mutant α-tropomyosinslow (R168C) to filamentous actin. Single fibre contractility studies of patient myofibres revealed marked slow myofibre specific abnormalities. At saturating [Ca(2+)] (pCa 4.5), patient slow fibres produced only 63% of the contractile force produced in control slow fibres and had reduced acto-myosin cross-bridge cycling kinetics. Importantly, due to reduced Ca(2+)-sensitivity, at sub-saturating [Ca(2+)] (pCa 6, levels typically released during in vivo contraction) patient slow fibres produced only 26% of the force generated by control slow fibres. Thus, weakness in TPM3-myopathy patients can be directly attributed to reduced slow fibre force at physiological [Ca(2+)], and impaired acto-myosin cross-bridge cycling kinetics. Fast myofibres are spared; however, they appear to be unable to compensate for slow fibre dysfunction. Abnormal Ca(2+)-sensitivity in TPM3-myopathy patients suggests Ca(2+)-sensitizing drugs may represent a useful treatment for this condition.
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Affiliation(s)
- Michaela Yuen
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia,
| | - Sandra T Cooper
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Steve B Marston
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Kristen J Nowak
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Elyshia McNamara
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Nancy Mokbel
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Faculty of Health Sciences, St. George Health Complex, The University of Balamand, Beirut, Lebanon
| | - Biljana Ilkovski
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia
| | - Gianina Ravenscroft
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - John Rendu
- Département de Biochimie Toxicologie et Pharmacologie, Département de Biochimie Génétique et Moléculaire, Centre Hospitalier Universitaire de Grenoble, Grenoble, France
| | - Josine M de Winter
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Lars Klinge
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Neurology, Faculty of Medicine, Georg August University, Göttingen, Germany
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kathryn N North
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia, Murdoch Children's Research Institute, the Royal Children's Hospital, Parkville, Australia and Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Coen A C Ottenheijm
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Nigel F Clarke
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
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