Mutations in the cardiac myosin regulatory light chain (RLC, MYL2 gene) are known to cause inherited cardiomyopathies with variable phenotypes. In this study, we investigated the impact of a mutation in the RLC (K104E) that is associated with hypertrophic cardiomyopathy (HCM). Previously in a mouse model of K104E, older animals were found to develop cardiac hypertrophy, fibrosis, and diastolic dysfunction, suggesting a slow development of HCM. However, variable penetrance of the mutation in human populations suggests that the impact of K104E may be subtle. Therefore, we generated human cardiac myosin subfragment-1 (M2β-S1) and exchanged on either the wild type (WT) or K104E human ventricular RLC in order to assess the impact of the mutation on the mechanochemical properties of cardiac myosin. The maximum actin-activated ATPase activity and actin sliding velocities in the in vitro motility assay were similar in M2β-S1 WT and K104E, as were the detachment kinetic parameters, including the rate of ATP-induced dissociation and the ADP release rate constant. We also examined the mechanical performance of α-cardiac myosin extracted from transgenic (Tg) mice expressing human wild type RLC (Tg WT) or mutant RLC (Tg K104E). We found that α-cardiac myosin from Tg K104E animals demonstrated enhanced actin sliding velocities in the motility assay compared with its Tg WT counterpart. Furthermore, the degree of incorporation of the mutant RLC into α-cardiac myosin in the transgenic animals was significantly reduced compared with wild type. Therefore, we conclude that the impact of the K104E mutation depends on either the length or the isoform of the myosin heavy chain backbone and that the mutation may disrupt RLC interactions with the myosin lever arm domain.
|Journal||Journal of General Physiology|
|State||Published - Jul 5 2021|
Bibliographical noteFunding Information:
Henk L. Granzier served as editor. We would like to acknowledge Rohini Desetty for her outstanding technical assistance in the Yengo laboratory at Penn State College of Medicine. We also acknowledge C. Kurtis Mann, Hossein Sharifi, and Alexus Rockward at the University of Kentucky for their assistance with the Tg mouse colonies. This work was supported by National Institutes of Health grants HL127699 (to C.M. Yengo), HL133359 (to K.S. Campbell and J.F. Wenk), HL124041 (to M.J. Previs), and HL143830 (to D. Szczesna-Cordary).
This work was supported by National Institutes of Health grants HL127699 (to C.M. Yengo), HL133359 (to K.S. Campbell and J.F. Wenk), HL124041 (to M.J. Previs), and HL143830 (to D. Szczesna-Cordary). The authors declare no competing financial interests.
© 2021 Rasicci et al.
- Contraction and cell motility
- Molecular physiology
- Myofilament special issue
ASJC Scopus subject areas