The carboxyl terminus of myosin binding protein C (MyBP-C, C-protein) specifies incorporation into the A-band of striated muscle

1996 ◽  
Vol 109 (1) ◽  
pp. 101-111 ◽  
Author(s):  
R. Gilbert ◽  
M.G. Kelly ◽  
T. Mikawa ◽  
D.A. Fischman
Keyword(s):  
Amino Acids ◽  
Protein C ◽  
Binding Protein ◽  
Thick Filament ◽  
Binding Domain ◽  
C Protein ◽  
Amino Terminal ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Myosin Binding

Myosin binding protein-C (MyBP-C), also known as C-protein, is a major constituent of the thick filaments of vertebrate striated muscles. The protein, approximately 130 kDa, consists of a series of 10 globular motifs (numbered I to X) each of approximately 90–100 amino acids, bearing resemblance to the C2-set of immunoglobins (Ig C2) and to the fibronectin type III (FnIII) motifs. Using pure preparations of myosin and MyBP-C, it has been demonstrated that the major myosin binding domain of MyBP-C resides within the C-terminal Ig C2 motif (motif X). However, in the context of the in vivo thick filament, it is uncertain if the latter domain is sufficient to target MyBP-C correctly to the A-band or if other regions of the molecule are required for this process. To answer this question, cultures of skeletal muscle myoblasts were transfected with expression plasmids encoding seven truncation mutants of MyBP-C, and their targeting to the A-band investigated by immunofluorescence microscopy. To distinguish the recombinant proteins from endogenous MyBP-C, a myc epitope was inserted at each amino terminus. Recombinant MyBP-C exhibited an identical distribution in the sarcomere to that of native MyBP-C; i.e. it was found exclusively in the C-zone of the A-band. A mutant encoding the C-terminal 372 amino acids, but lacking motifs I-VI (termed delta 1–6), also targeted correctly to the A-band. This fragment, which is composed of two Ig C2 and two FnIII motifs, was the minimal protein fragment required for correct A-band incorporation. Larger amino-terminal deletions or deletion of motif X, the myosin binding domain, abolished all localization to the A-band. One construct (delta 10) lacking only motif X strongly inhibited myofibril assembly. We conclude that the myosin binding domain of MyBP-C, although essential, is not sufficient for correct incorporation into the A-band and that motifs VII to IX are required for this process. The data suggest a topological model in which MyBP-C is associated with the thick filament through its C terminus.

Abstract 376: Amino Terminal C0-C1f Region of Cardiac Myosin Binding Protein-C is Essential for Normal Cardiac Function

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Thomas L Lynch ◽  
Diederik W Kuster ◽  
David Barefield ◽  
Mayandi Sivaguru ◽  
Michael J Previs ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Protein C ◽  
Binding Protein ◽  
Cardiac Myosin ◽  
Amino Terminal ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Thick Filaments ◽  
Myosin Binding

Rationale: Cardiac myosin binding protein-C (cMyBP-C) is a trans-filament protein that has been shown to regulate cardiac function via its amino terminal (N’) regions. However, it is unknown whether the first 271 residues (C0-C1f region) are necessary to regulate contractile function in vivo. Hypothesis: The N’-region of cMyBP-C is critical for proper cardiac function in vivo. Methods and Results: Transgenic mice with approximately 80% expression of mutant truncated cMyBP-C missing C0-C1f (cMyBP-C 110kDa ), compared to endogenous cMyBP-C, were generated and characterized at 3-months of age. cMyBP-C 110kDa hearts had significantly elevated heart weight/body weight ratio, fibrosis, nuclear area and collagen content compared to hearts from non-transgenic (NTG) littermates. Electron microscopic analysis revealed normal sarcomere structure in cMyBP-C 110kDa hearts but with apparently weaker cMyBP-C stripes. Furthermore, the ability of cMyBP-C to slow actin-filament sliding within the C-zone of native thick filaments isolated from NTG hearts was lost on thick filaments from cMyBP-C 110kDa hearts. Short axis M-mode echocardiography revealed a significant increase in left ventricular (LV) internal diameter during diastole in cMyBP-C 110kDa hearts. Importantly, cMyBP-C 110kDa hearts displayed a significant reduction in fractional shortening compared to hearts from NTG littermates. We further observed a decrease in the thickness of the LV interventricular septum and free wall during systole in cMyBP-C 110kDa hearts. Strain analysis using images acquired from ECG-Gated Kilohertz Visualization identified a significant deficit in global longitudinal strain in cMyBP-C 110kDa hearts compared to NTG hearts. Conclusion: The N’-region of cMyBP-C is indispensable for maintaining normal cardiac morphology and function and loss of this region promotes contractile dysfunction both at the molecular and tissue levels.

scholarly journals Cardiac Myosin Binding Protein-C Is Essential for Thick-Filament Stability and Flexural Rigidity

2009 ◽  
Vol 96 (8) ◽  
pp. 3273-3280 ◽  
Author(s):  
Lori R. Nyland ◽  
Bradley M. Palmer ◽  
Zengyi Chen ◽  
David W. Maughan ◽  
Christine E. Seidman ◽  
...  
Keyword(s):  
Protein C ◽  
Flexural Rigidity ◽  
Binding Protein ◽  
Thick Filament ◽  
Cardiac Myosin ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Myosin Binding

scholarly journals 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

2021 ◽  
Vol 22 (21) ◽  
pp. 11949
Author(s):  
Frederic V. Schwäbe ◽  
Emanuel K. Peter ◽  
Manuel H. Taft ◽  
Dietmar J. Manstein
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Protein Interactions ◽  
Protein C ◽  
Binding Protein ◽  
Thick Filament ◽  
C2 Domain ◽  
Double Mutation ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Myosin Binding

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.

Effect of cardiac myosin-binding protein C on stability of the thick filament

2004 ◽  
Vol 37 (4) ◽  
pp. 823-835 ◽  
Author(s):  
G. McClellan ◽  
I. Kulikovskaya ◽  
J. Flavigny ◽  
L. Carrier ◽  
S. Winegrad
Keyword(s):  
Protein C ◽  
Binding Protein ◽  
Thick Filament ◽  
Cardiac Myosin ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Myosin Binding

scholarly journals Localization of the binding site of the C-terminal domain of cardiac myosin-binding protein-C on the myosin rod

2006 ◽  
Vol 401 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Emily Flashman ◽  
Hugh Watkins ◽  
Charles Redwood
Keyword(s):  
Binding Site ◽  
Protein C ◽  
Binding Protein ◽  
Thick Filament ◽  
Full Length ◽  
Terminal Domain ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Myosin Binding ◽  
Myosin Rod

cMyBP-C [cardiac (MyBP-C) myosin-binding protein-C)] is a sarcomeric protein involved both in thick filament structure and in the regulation of contractility. It is composed of eight IgI-like and three fibronectin-3-like domains (termed C0–C10). Mutations in the gene encoding cMyBP-C are a principal cause of HCM (hypertrophic cardiomyopathy). cMyBP-C binds to the LMM (light meromyosin) portion of the myosin rod via its C-terminal domain, C10. We investigated this interaction in detail to determine whether HCM mutations in β myosin heavy chain located within the LMM portion alter the binding of cMyBP-C, and to define the precise region of LMM that binds C10 to aid in developing models of the arrangement of MyBP-C on the thick filament. In co-sedimentation experiments recombinant C10 bound full-length LMM with a Kd of 3.52 μM and at a stoichiometry of 1.14 C10 per LMM. C10 was also shown to bind with similar affinity to LMM containing either the HCM mutations A1379T or S1776G, suggesting that these HCM mutations do not perturb C10 binding. Using a range of N-terminally truncated LMM fragments, the cMyBP-C-binding site on LMM was shown to lie between residues 1554 and 1581. Since it had been reported previously that acidic residues on myosin mediate the C10 interaction, three clusters of acidic amino acids (Glu1554/Glu1555, Glu1571/Glu1573 and Glu1578/Asp1580/Glu1581/Glu1582) were mutated in full-length LMM and the proteins tested for C10 binding. No effect of these mutations on C10 binding was however detected. We interpret our results with respect to the localization of the proposed trimeric collar on the thick filament.

scholarly journals Inotropic interventions do not change the resting state of myosin motors during cardiac diastole

2018 ◽  
Vol 151 (1) ◽  
pp. 53-65 ◽  
Author(s):  
Marco Caremani ◽  
Francesca Pinzauti ◽  
Joseph D. Powers ◽  
Serena Governali ◽  
Theyencheri Narayanan ◽  
...  
Keyword(s):  
Protein C ◽  
Thin Filament ◽  
Sarcomere Length ◽  
Binding Protein ◽  
Thick Filament ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Filament Activation ◽  
Myosin Binding ◽  
Myosin Motors

When striated (skeletal and cardiac) muscle is in its relaxed state, myosin motors are packed in helical tracks on the surface of the thick filament, folded toward the center of the sarcomere, and unable to bind actin or hydrolyze ATP (OFF state). This raises the question of whatthe mechanism is that integrates the Ca2+-dependent thin filament activation, making myosin heads available for interaction with actin. Here we test the interdependency of the thin and thick filament regulatory mechanisms in intact trabeculae from the rat heart. We record the x-ray diffraction signals that mark the state of the thick filament during inotropic interventions (increase in sarcomere length from 1.95 to 2.25 µm and addition of 10−7 M isoprenaline), which potentiate the twitch force developed by an electrically paced trabecula by up to twofold. During diastole, none of the signals related to the OFF state of the thick filament are significantly affected by these interventions, except the intensity of both myosin-binding protein C– and troponin-related meridional reflections, which reduce by 20% in the presence of isoprenaline. These results indicate that recruitment of myosin motors from their OFF state occurs independently and downstream from thin filament activation. This is in agreement with the recently discovered mechanism based on thick filament mechanosensing in which the number of motors available for interaction with actin rapidly adapts to the stress on the thick filament and thus to the loading conditions of the contraction. The gain of this positive feedback may be modulated by both sarcomere length and the degree of phosphorylation of myosin-binding protein C.

Sign in / Sign up

Export Citation Format

Share Document