TY - JOUR
T1 - Cardiomyopathy-linked myosin regulatory light chain mutations disrupt myosin strain-dependent biochemistry
AU - Greenberg, Michael J.
AU - Kazmierczak, Katarzyna
AU - Szczesna-Cordary, Danuta
AU - Moore, Jeffrey R.
PY - 2010/10/5
Y1 - 2010/10/5
N2 - Familial hypertrophic cardiomyopathy (FHC) is caused by mutations in sarcomeric proteins including the myosin regulatory light chain (RLC). Two such FHC mutations, R58Q and N47K, located near the cationic binding site of the RLC, have been identified from population studies. To examine the molecular basis for the observed phenotypes, we exchanged endogenous RLC from native porcine cardiac myosin with recombinant human ventricular wild type (WT) or FHC mutant RLC and examined the ability of the reconstituted myosin to propel actin filament sliding using the in vitro motility assay. We find that, whereas the mutant myosins are indistinguishable from the controls (WT or native myosin) under unloaded conditions, both R58Q- and N47K-exchanged myosins show reductions in force and power output compared with WT or native myosin. We also show that the changes in loaded kinetics are a result of mutation-induced loss of myosin strain sensitivity of ADP affinity. Wepropose that the R58Q and N47K mutations alter the mechanical properties of the myosin neck region, leading to altered load-dependent kinetics that may explain the observed mutant-induced FHC phenotypes.
AB - Familial hypertrophic cardiomyopathy (FHC) is caused by mutations in sarcomeric proteins including the myosin regulatory light chain (RLC). Two such FHC mutations, R58Q and N47K, located near the cationic binding site of the RLC, have been identified from population studies. To examine the molecular basis for the observed phenotypes, we exchanged endogenous RLC from native porcine cardiac myosin with recombinant human ventricular wild type (WT) or FHC mutant RLC and examined the ability of the reconstituted myosin to propel actin filament sliding using the in vitro motility assay. We find that, whereas the mutant myosins are indistinguishable from the controls (WT or native myosin) under unloaded conditions, both R58Q- and N47K-exchanged myosins show reductions in force and power output compared with WT or native myosin. We also show that the changes in loaded kinetics are a result of mutation-induced loss of myosin strain sensitivity of ADP affinity. Wepropose that the R58Q and N47K mutations alter the mechanical properties of the myosin neck region, leading to altered load-dependent kinetics that may explain the observed mutant-induced FHC phenotypes.
KW - Familial hypertrophic cardiomyopathy
KW - In vitro motility
KW - Load-dependent kinetics
KW - N47K
KW - R58Q
UR - http://www.scopus.com/inward/record.url?scp=78049252301&partnerID=8YFLogxK
U2 - 10.1073/pnas.1009619107
DO - 10.1073/pnas.1009619107
M3 - Article
C2 - 20855589
AN - SCOPUS:78049252301
SN - 0027-8424
VL - 107
SP - 17403
EP - 17408
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 40
ER -