Molecular basis of force-pCa relation in <i>MYL2</i> cardiomyopathy mice: Role of the super-relaxed state of myosin

Abstract

activation. The HCM-D166V model also disrupted the SRX state and promoted an SRX-to-DRX (super-relaxed to disordered relaxed) transition that correlated with an HCM-linked phenotype of hypercontractility. While this dysregulation of SRX ↔ DRX equilibrium was consistent with repositioning of myosin motors closer to the thin filaments and with increased force-pCa dependence for HCM-D166V, the DCM-D94A model favored the energy-conserving SRX state, but the structure/function-pCa data were similar to WT. Our results suggest that the mutation-induced redistribution of myosin energetic states is one of the key mechanisms contributing to the development of complex clinical phenotypes associated with human HCM-D166V and DCM-D94A mutations.