title: Impact of familial hypertrophic cardiomyopathy-linked mutations in the NH2 terminus of the RLC on β-myosin cross-bridge mechanics.
abstract: Familial hypertrophic cardiomyopathy (HCM) is associated with mutations in sarcomeric proteins, including the myosin regulatory light chain (RLC). Here we studied the impact of three HCM mutations located in the NH2 terminus of the RLC on the molecular mechanism of β-myosin heavy chain (MHC) cross-bridge mechanics using the in vitro motility assay. To generate mutant β-myosin, native RLC was depleted from porcine cardiac MHC and reconstituted with mutant (A13T, F18L, and E22K) or wild-type (WT) human cardiac RLC. We characterized the mutant myosin force and motion generation capability in the presence of a frictional load. Compared with WT, all three mutants exhibited reductions in maximal actin filament velocity when tested under low or no frictional load. The actin-activated ATPase showed no significant difference between WT and HCM-mutant-reconstituted myosins. The decrease in velocity has been attributed to a significantly increased duty cycle, as was measured by the dependence of actin sliding velocity on myosin surface density, for all three mutant myosins. These results demonstrate a mutation-induced alteration in acto-myosin interactions that may contribute to the pathogenesis of HCM.
authors.affiliation: Department of Physiology and Biophysics, Boston University, Boston, Massachusetts; and.
authors.forename: Gerrie P
authors.initials: GP
authors.lastname: Farman
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami, Miami, Florida.
authors.forename: Priya
authors.initials: P
authors.lastname: Muthu
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami, Miami, Florida.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kazmierczak
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami, Miami, Florida.
authors.forename: Danuta
authors.initials: D
authors.lastname: Szczesna-Cordary
authors.affiliation: Department of Physiology and Biophysics, Boston University, Boston, Massachusetts; and jxmoore@bu.edu.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Moore
mesh_terms: D000818:Animals; D024722:Cardiac Myosins / Q000378:metabolism*; D024741:Cardiomyopathy, Hypertrophic, Familial / Q000235:genetics* / Q000378:metabolism* / Q000503:physiopathology; D020022:Genetic Predisposition to Disease; D006801:Humans; D007700:Kinetics; D009154:Mutation; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000378:metabolism*; D018994:Myosin Light Chains / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000378:metabolism; D013552:Swine
chemical_list: D018994:Myosin Light Chains; D011994:Recombinant Proteins; D024722:Cardiac Myosins; D018995:Myosin Heavy Chains
keywords: cardiac ventricular myosin; hypertrophic cardiomyopathy; in vitro motility; myosin regulatory light chain