1
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Thomasen FE, Skaalum T, Kumar A, Srinivasan S, Vanni S, Lindorff-Larsen K. Rescaling protein-protein interactions improves Martini 3 for flexible proteins in solution. Nat Commun 2024; 15:6645. [PMID: 39103332 DOI: 10.1038/s41467-024-50647-9] [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: 05/29/2023] [Accepted: 07/15/2024] [Indexed: 08/07/2024] Open
Abstract
Multidomain proteins with flexible linkers and disordered regions play important roles in many cellular processes, but characterizing their conformational ensembles is difficult. We have previously shown that the coarse-grained model, Martini 3, produces too compact ensembles in solution, that may in part be remedied by strengthening protein-water interactions. Here, we show that decreasing the strength of protein-protein interactions leads to improved agreement with experimental data on a wide set of systems. We show that the 'symmetry' between rescaling protein-water and protein-protein interactions breaks down when studying interactions with or within membranes; rescaling protein-protein interactions better preserves the binding specificity of proteins with lipid membranes, whereas rescaling protein-water interactions preserves oligomerization of transmembrane helices. We conclude that decreasing the strength of protein-protein interactions improves the accuracy of Martini 3 for IDPs and multidomain proteins, both in solution and in the presence of a lipid membrane.
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Affiliation(s)
- F Emil Thomasen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, DK-2200, Copenhagen N, Denmark.
| | - Tórur Skaalum
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, DK-2200, Copenhagen N, Denmark
| | - Ashutosh Kumar
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- Swiss National Center for Competence in Research (NCCR) Bio-inspired Materials, University of Fribourg, Chemin des Verdiers 4, CH-1700, Fribourg, Switzerland
| | | | - Stefano Vanni
- Department of Biology, University of Fribourg, Fribourg, Switzerland.
- Swiss National Center for Competence in Research (NCCR) Bio-inspired Materials, University of Fribourg, Chemin des Verdiers 4, CH-1700, Fribourg, Switzerland.
| | - Kresten Lindorff-Larsen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, DK-2200, Copenhagen N, Denmark.
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2
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Doh CY, Schmidt AV, Chinthalapudi K, Stelzer JE. Bringing into focus the central domains C3-C6 of myosin binding protein C. Front Physiol 2024; 15:1370539. [PMID: 38487262 PMCID: PMC10937550 DOI: 10.3389/fphys.2024.1370539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 02/19/2024] [Indexed: 03/17/2024] Open
Abstract
Myosin binding protein C (MyBPC) is a multi-domain protein with each region having a distinct functional role in muscle contraction. The central domains of MyBPC have often been overlooked due to their unclear roles. However, recent research shows promise in understanding their potential structural and regulatory functions. Understanding the central region of MyBPC is important because it may have specialized function that can be used as drug targets or for disease-specific therapies. In this review, we provide a brief overview of the evolution of our understanding of the central domains of MyBPC in regard to its domain structures, arrangement and dynamics, interaction partners, hypothesized functions, disease-causing mutations, and post-translational modifications. We highlight key research studies that have helped advance our understanding of the central region. Lastly, we discuss gaps in our current understanding and potential avenues to further research and discovery.
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Affiliation(s)
- Chang Yoon Doh
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Alexandra V. Schmidt
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Krishna Chinthalapudi
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart & Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH, United States
| | - Julian E. Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
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3
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Pearce A, Ponnam S, Holt MR, Randall T, Beckingham R, Kho AL, Kampourakis T, Ehler E. Missense mutations in the central domains of cardiac myosin binding protein-C and their potential contribution to hypertrophic cardiomyopathy. J Biol Chem 2024; 300:105511. [PMID: 38042491 PMCID: PMC10772716 DOI: 10.1016/j.jbc.2023.105511] [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: 06/01/2023] [Revised: 11/05/2023] [Accepted: 11/20/2023] [Indexed: 12/04/2023] Open
Abstract
Myosin binding protein-C (MyBP-C) is a multidomain protein that regulates muscle contraction. Mutations in MYBPC3, the gene encoding for the cardiac variant (henceforth called cMyBP-C), are amongst the most frequent causes of hypertrophic cardiomyopathy. Most mutations lead to a truncated version of cMyBP-C, which is most likely unstable. However, missense mutations have also been reported, which tend to cluster in the central domains of the cMyBP-C molecule. This suggests that these central domains are more than just a passive spacer between the better characterized N- and C-terminal domains. Here, we investigated the potential impact of four different missense mutations, E542Q, G596R, N755K, and R820Q, which are spread over the domains C3 to C6, on the function of MyBP-C on both the isolated protein level and in cardiomyocytes in vitro. Effect on domain stability, interaction with thin filaments, binding to myosin, and subcellular localization behavior were assessed. Our studies show that these missense mutations result in slightly different phenotypes at the molecular level, which are mutation specific. The expected functional readout of each mutation provides a valid explanation for why cMyBP-C fails to work as a brake in the regulation of muscle contraction, which eventually results in a hypertrophic cardiomyopathy phenotype. We conclude that missense mutations in cMyBP-C must be evaluated in context of their domain localization, their effect on interaction with thin filaments and myosin, and their effect on protein stability to explain how they lead to disease.
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Affiliation(s)
- Amy Pearce
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Saraswathi Ponnam
- British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics (School of Basic and Biosciences), King's College London, London, United Kingdom
| | - Mark R Holt
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Thomas Randall
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Rylan Beckingham
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Ay Lin Kho
- British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics (School of Basic and Biosciences), King's College London, London, United Kingdom
| | - Thomas Kampourakis
- British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics (School of Basic and Biosciences), King's College London, London, United Kingdom
| | - Elisabeth Ehler
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics (School of Basic and Biosciences), King's College London, London, United Kingdom.
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4
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Doh CY, Bharambe N, Holmes JB, Dominic KL, Swanberg CE, Mamidi R, Chen Y, Bandyopadhyay S, Ramachandran R, Stelzer JE. Molecular characterization of linker and loop-mediated structural modulation and hinge motion in the C4-C5 domains of cMyBPC. J Struct Biol 2022; 214:107856. [PMID: 35427781 PMCID: PMC9942529 DOI: 10.1016/j.jsb.2022.107856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 03/16/2022] [Accepted: 04/01/2022] [Indexed: 10/18/2022]
Abstract
INTRODUCTION The central C4 and C5 domains (C4C5) of cardiac myosin binding protein C (cMyBPC) contain a flexible interdomain linker and a cardiac-isoform specific loop. However, their importance in the functional regulation of cMyBPC has not been extensively studied. METHODS AND RESULTS We expressed recombinant C4C5 proteins with deleted linker and loop regions and performed biophysical experiments to determine each of their structural and dynamic roles. We show that the linker and C5 loop regions modulate the secondary structure and thermal stability of C4C5. Furthermore, we provide evidence through extended molecular dynamics simulations and principle component analyses that C4C5 can adopt a completely bent or latched conformation. The simulation trajectory and interaction network analyses reveal that the completely bent conformation of C4C5 exhibits a specific pattern of residue-level interactions. Therefore, we propose a "hinge-and-latch" mechanism where the linker allows a great degree of flexibility and bending, while the loop aids in achieving a completely bent and latched conformation. Although this may be one of many bent positions that C4C5 can adopt, we illustrate for the first time in molecular detail that this type of large scale conformational change can occur in the central domains of cMyBPC. CONCLUSIONS Our hinge-and-latch mechanism demonstrates that the linker and loop regions participate in dynamic modulation of cMyBPC's motion and global conformation. These structural and dynamic features may contribute to muscle isoform-specific regulation of actomyosin activity, and have potential implications regarding its ability to propagate or retract cMyBPC's regulatory N-terminal domains.
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Affiliation(s)
- Chang Yoon Doh
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Nikhil Bharambe
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Joshua B. Holmes
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Katherine L. Dominic
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Caitlin E. Swanberg
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Yinghua Chen
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Smarajit Bandyopadhyay
- Molecular Biotechnology Core, Shared Laboratory Resources, Cleveland Clinic, Cleveland, OH, USA
| | - Rajesh Ramachandran
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Julian E. Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA,Corresponding author at: Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 2109 Adelbert Rd, Robbins E522, Cleveland, OH 44106, USA. (J.E. Stelzer)
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5
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Microscale thermophoresis suggests a new model of regulation of cardiac myosin function via interaction with cardiac myosin-binding protein C. J Biol Chem 2021; 298:101485. [PMID: 34915024 PMCID: PMC8733265 DOI: 10.1016/j.jbc.2021.101485] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 11/24/2021] [Accepted: 12/03/2021] [Indexed: 12/02/2022] Open
Abstract
The cardiac isoform of myosin-binding protein C (cMyBP-C) is a key regulatory protein found in cardiac myofilaments that can control the activation state of both the actin-containing thin and myosin-containing thick filaments. However, in contrast to thin filament–based mechanisms of regulation, the mechanism of myosin-based regulation by cMyBP-C has yet to be defined in detail. To clarify its function in this process, we used microscale thermophoresis to build an extensive interaction map between cMyBP-C and isolated fragments of β-cardiac myosin. We show here that the regulatory N-terminal domains (C0C2) of cMyBP-C interact with both the myosin head (myosin S1) and tail domains (myosin S2) with micromolar affinity via phosphorylation-independent and phosphorylation-dependent interactions of domain C1 and the cardiac-specific m-motif, respectively. Moreover, we show that the interaction sites with the highest affinity between cMyBP-C and myosin S1 are localized to its central domains, which bind myosin with submicromolar affinity. We identified two separate interaction regions in the central C2C4 and C5C7 segments that compete for the same binding site on myosin S1, suggesting that cMyBP-C can crosslink the two myosin heads of a single myosin molecule and thereby stabilize it in the folded OFF state. Phosphorylation of the cardiac-specific m-motif by protein kinase A had no effect on the binding of either the N-terminal or the central segments to the myosin head domain, suggesting this might therefore represent a constitutively bound state of myosin associated with cMyBP-C. Based on our results, we propose a new model of regulation of cardiac myosin function by cMyBP-C.
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6
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Schwäbe FV, Peter EK, Taft MH, Manstein DJ. Assessment of the Contribution of a Thermodynamic and Mechanical Destabilization of Myosin-Binding Protein C Domain C2 to the Pathomechanism of Hypertrophic Cardiomyopathy-Causing Double Mutation MYBPC3Δ25bp/D389V. Int J Mol Sci 2021; 22:ijms222111949. [PMID: 34769381 PMCID: PMC8584774 DOI: 10.3390/ijms222111949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/31/2021] [Accepted: 11/02/2021] [Indexed: 01/01/2023] Open
Abstract
Mutations in the gene encoding cardiac myosin-binding protein-C (MyBPC), a thick filament assembly protein that stabilizes sarcomeric structure and regulates cardiac function, are a common cause for the development of hypertrophic cardiomyopathy. About 10% of carriers of the Δ25bp variant of MYBPC3, which is common in individuals from South Asia, are also carriers of the D389V variant on the same allele. Compared with noncarriers and those with MYBPC3Δ25bp alone, indicators for the development of hypertrophic cardiomyopathy occur with increased frequency in MYBPC3Δ25bp/D389V carriers. Residue D389 lies in the IgI-like C2 domain that is part of the N-terminal region of MyBPC. To probe the effects of mutation D389V on structure, thermostability, and protein–protein interactions, we produced and characterized wild-type and mutant constructs corresponding to the isolated 10 kDa C2 domain and a 52 kDa N-terminal fragment that includes subdomains C0 to C2. Our results show marked reductions in the melting temperatures of D389V mutant constructs. Interactions of construct C0–C2 D389V with the cardiac isoforms of myosin-2 and actin remain unchanged. Molecular dynamics simulations reveal changes in the stiffness and conformer dynamics of domain C2 caused by mutation D389V. Our results suggest a pathomechanism for the development of HCM based on the toxic buildup of misfolded protein in young MYBPC3Δ25bp/D389V carriers that is supplanted and enhanced by C-zone haploinsufficiency at older ages.
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Affiliation(s)
- Frederic V. Schwäbe
- Fritz Hartmann Centre for Medical Research, Institute for Biophysical Chemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany; (F.V.S.); (E.K.P.); (M.H.T.)
| | - Emanuel K. Peter
- Fritz Hartmann Centre for Medical Research, Institute for Biophysical Chemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany; (F.V.S.); (E.K.P.); (M.H.T.)
| | - Manuel H. Taft
- Fritz Hartmann Centre for Medical Research, Institute for Biophysical Chemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany; (F.V.S.); (E.K.P.); (M.H.T.)
| | - Dietmar J. Manstein
- Fritz Hartmann Centre for Medical Research, Institute for Biophysical Chemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany; (F.V.S.); (E.K.P.); (M.H.T.)
- Division for Structural Biochemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany
- Correspondence:
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7
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Oldt RF, Bussey KJ, Settles ML, Fass JN, Roberts JA, Reader JR, Komandoor S, Abrich VA, Kanthaswamy S. MYBPC3 Haplotype Linked to Hypertrophic Cardiomyopathy in Rhesus Macaques ( Macaca mulatta). Comp Med 2020; 70:358-367. [PMID: 32753092 PMCID: PMC7574221 DOI: 10.30802/aalas-cm-19-000108] [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: 11/07/2019] [Revised: 01/13/2020] [Accepted: 02/07/2020] [Indexed: 11/05/2022]
Abstract
In humans, abnormal thickening of the left ventricle of the heart clinically defines hypertrophic cardiomyopathy (HCM), a common inherited cardiovascular disorder that can precede a sudden cardiac death event. The wide range of clinical presentations in HCM obscures genetic variants that may influence an individual's susceptibility to sudden cardiac death. Although exon sequencing of major sarcomere genes can be used to detect high-impact causal mutations, this strategy is successful in only half of patient cases. The incidence of left ventricular hypertrophy (LVH) in a managed research colony of rhesus macaques provides an excellent comparative model in which to explore the genomic etiology of severe HCM and sudden cardiac death. Because no rhesus HCM-associated mutations have been reported, we used a next-generation genotyping assay that targets 7 sarcomeric rhesus genes within 63 genomic sites that are orthologous to human genomic regions known to harbor HCM disease variants. Amplicon sequencing was performed on 52 macaques with confirmed LVH and 42 unrelated, unaffected animals representing both the Indian and Chinese rhesus macaque subspecies. Bias-reduced logistic regression uncovered a risk haplotype in the rhesus MYBPC3 gene, which is frequently disrupted in both human and feline HCM; this haplotype implicates an intronic variant strongly associated with disease in either homozygous or carrier form. Our results highlight that leveraging evolutionary genomic data provides a unique, practical strategy for minimizing population bias in complex disease studies.
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Affiliation(s)
- Robert F Oldt
- School of Mathematical and Natural Sciences, Arizona State University at the West Campus, Glendale, Arizona; Evolutionary Biology Graduate Program, School of Life Sciences, Arizona State University at the West Campus, Glendale, Arizona;,
| | - Kimberly J Bussey
- School of Mathematical and Natural Sciences, Arizona State University at the West Campus, Glendale, Arizona; BEYOND Center for Fundamental Concepts in Science, Arizona State University at the West Campus, Glendale, Arizona
| | - Matthew L Settles
- Bioinformatics Core, UC Davis Genome Center, University of California, Davis, California
| | - Joseph N Fass
- Bioinformatics Core, UC Davis Genome Center, University of California, Davis, California
| | - Jeffrey A Roberts
- California National Primate Research Center, University of California, Davis, California
| | - J Rachel Reader
- California National Primate Research Center, University of California, Davis, California
| | | | - Victor A Abrich
- Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, Arizona
| | - Sreetharan Kanthaswamy
- School of Mathematical and Natural Sciences, Arizona State University at the West Campus, Glendale, Arizona; Evolutionary Biology Graduate Program, School of Life Sciences, Arizona State University at the West Campus, Glendale, Arizona; California National Primate Research Center, University of California, Davis, California
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8
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Pricolo MR, Herrero-Galán E, Mazzaccara C, Losi MA, Alegre-Cebollada J, Frisso G. Protein Thermodynamic Destabilization in the Assessment of Pathogenicity of a Variant of Uncertain Significance in Cardiac Myosin Binding Protein C. J Cardiovasc Transl Res 2020; 13:867-877. [PMID: 32034629 DOI: 10.1007/s12265-020-09959-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 01/20/2020] [Indexed: 12/29/2022]
Abstract
In the era of next generation sequencing (NGS), genetic testing for inherited disorders identifies an ever-increasing number of variants whose pathogenicity remains unclear. These variants of uncertain significance (VUS) limit the reach of genetic testing in clinical practice. The VUS for hypertrophic cardiomyopathy (HCM), the most common familial heart disease, constitute over 60% of entries for missense variants shown in ClinVar database. We have studied a novel VUS (c.1809T>G-p.I603M) in the most frequently mutated gene in HCM, MYBPC3, which codes for cardiac myosin-binding protein C (cMyBPC). Our determinations of pathogenicity integrate bioinformatics evaluation and functional studies of RNA splicing and protein thermodynamic stability. In silico prediction and mRNA analysis indicated no alteration of RNA splicing induced by the variant. At the protein level, the p.I603M mutation maps to the C4 domain of cMyBPC. Although the mutation does not perturb much the overall structure of the C4 domain, the stability of C4 I603M is severely compromised as detected by circular dichroism and differential scanning calorimetry experiments. Taking into account the highly destabilizing effect of the mutation in the structure of C4, we propose reclassification of variant p.I603M as likely pathogenic. Looking into the future, the workflow described here can be used to refine the assignment of pathogenicity of variants of uncertain significance in MYBPC3.
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Affiliation(s)
- Maria Rosaria Pricolo
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain. .,Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Naples, Italy.
| | - Elías Herrero-Galán
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
| | - Cristina Mazzaccara
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Naples, Italy.,CEINGE Biotecnologie Avanzate s.c. a r.l., Naples, Italy
| | - Maria Angela Losi
- Dipartimento di Scienze Biomediche Avanzate, Università Federico II, Naples, Italy
| | | | - Giulia Frisso
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Naples, Italy.,CEINGE Biotecnologie Avanzate s.c. a r.l., Naples, Italy
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9
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Smelter DF, de Lange WJ, Cai W, Ge Y, Ralphe JC. The HCM-linked W792R mutation in cardiac myosin-binding protein C reduces C6 FnIII domain stability. Am J Physiol Heart Circ Physiol 2018; 314:H1179-H1191. [PMID: 29451820 DOI: 10.1152/ajpheart.00686.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cardiac myosin-binding protein C (cMyBP-C) is a functional sarcomeric protein that regulates contractility in response to contractile demand, and many mutations in cMyBP-C lead to hypertrophic cardiomyopathy (HCM). To gain insight into the effects of disease-causing cMyBP-C missense mutations on contractile function, we expressed the pathogenic W792R mutation (substitution of a highly conserved tryptophan residue by an arginine residue at position 792) in mouse cardiomyocytes lacking endogenous cMyBP-C and studied the functional effects using three-dimensional engineered cardiac tissue constructs (mECTs). Based on complete conservation of tryptophan at this location in fibronectin type II (FnIII) domains, we hypothesized that the W792R mutation affects folding of the C6 FnIII domain, destabilizing the mutant protein. Adenoviral transduction of wild-type (WT) and W792R cDNA achieved equivalent mRNA transcript abundance, but not equivalent protein levels, with W792R compared with WT controls. mECTs expressing W792R demonstrated abnormal contractile kinetics compared with WT mECTs that were nearly identical to cMyBP-C-deficient mECTs. We studied whether common pathways of protein degradation were responsible for the rapid degradation of W792R cMyBP-C. Inhibition of both ubiquitin-proteasome and lysosomal degradation pathways failed to increase full-length mutant protein abundance to WT equivalence, suggesting rapid cytosolic degradation. Bacterial expression of WT and W792R protein fragments demonstrated decreased mutant stability with altered thermal denaturation and increased susceptibility to trypsin digestion. These data suggest that the W792R mutation destabilizes the C6 FnIII domain of cMyBP-C, resulting in decreased full-length protein expression. This study highlights the vulnerability of FnIII-like domains to mutations that alter domain stability and further indicates that missense mutations in cMyBP-C can cause disease through a mechanism of haploinsufficiency. NEW & NOTEWORTHY This study is one of the first to describe a disease mechanism for a missense mutation in cardiac myosin-binding protein C linked to hypertrophic cardiomyopathy. The mutation decreases stability of the fibronectin type III domain and results in substantially reduced mutant protein expression dissonant to transcript abundance.
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Affiliation(s)
- Dan F Smelter
- Department of Pediatrics, University of Wisconsin-Madison , Madison, Wisconsin
| | - Willem J de Lange
- Department of Pediatrics, University of Wisconsin-Madison , Madison, Wisconsin
| | - Wenxuan Cai
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison , Madison, Wisconsin.,Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison , Madison, Wisconsin
| | - Ying Ge
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison , Madison, Wisconsin.,Human Proteomics Program, University of Wisconsin-Madison , Madison, Wisconsin.,Department of Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison , Madison, Wisconsin
| | - J Carter Ralphe
- Department of Pediatrics, University of Wisconsin-Madison , Madison, Wisconsin
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10
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Small-angle scattering and 3D structure interpretation. Curr Opin Struct Biol 2016; 40:1-7. [DOI: 10.1016/j.sbi.2016.05.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 05/12/2016] [Accepted: 05/12/2016] [Indexed: 12/29/2022]
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11
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Németh E, Balogh RK, Borsos K, Czene A, Thulstrup PW, Gyurcsik B. Intrinsic protein disorder could be overlooked in cocrystallization conditions: An SRCD case study. Protein Sci 2016; 25:1977-1988. [PMID: 27508941 DOI: 10.1002/pro.3010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Accepted: 08/08/2016] [Indexed: 12/21/2022]
Abstract
X-ray diffractometry dominates protein studies, as it can provide 3D structures of these diverse macromolecules or their molecular complexes with interacting partners: substrates, inhibitors, and/or cofactors. Here, we show that under cocrystallization conditions the results could reflect induced protein folds instead of the (partially) disordered original structures. The analysis of synchrotron radiation circular dichroism spectra revealed that the Im7 immunity protein stabilizes the native-like solution structure of unfolded NColE7 nuclease mutants via complex formation. This is consistent with the fact that among the several available crystal structures with its inhibitor or substrate, all NColE7 structures are virtually the same. Our results draw attention to the possible structural consequence of protein modifications, which is often hidden by compensational effects of intermolecular interactions. The growing evidence on the importance of protein intrinsic disorder thus, demands more extensive complementary experiments in solution phase with the unligated form of the protein of interest.
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Affiliation(s)
- Eszter Németh
- Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged, 6720, Hungary.,MTA-SZTE, Bioinorganic Chemistry Research Group, Hungarian Academy of Sciences, Szeged, 6720, Hungary
| | - Ria K Balogh
- Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged, 6720, Hungary
| | - Katalin Borsos
- Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged, 6720, Hungary
| | - Anikó Czene
- MTA-SZTE, Bioinorganic Chemistry Research Group, Hungarian Academy of Sciences, Szeged, 6720, Hungary
| | - Peter W Thulstrup
- Department of Chemistry, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Béla Gyurcsik
- Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged, 6720, Hungary. .,MTA-SZTE, Bioinorganic Chemistry Research Group, Hungarian Academy of Sciences, Szeged, 6720, Hungary.
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