Properties of Cardiac Myosin with Cardiomyopathic Mutations in Essential Light Chains

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Daria S. Yampolskaya¹, Galina V. Kopylova², Daniil V. Shchepkin², Sergey Y. Bershitsky², Alexander M. Matyushenko¹, and Dmitrii I. Levitsky^1,a*

¹Bach Institute of Biochemistry, Biotechnology Research Center, Russian Academy of Sciences, 119071 Moscow, Russia

²Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia

^* To whom correspondence should be addressed.

Received September 9, 2022; Revised October 5, 2022; Accepted October 5, 2022

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The effects of cardiomyopathic mutations E56G, M149V, and E177G in the MYL3 gene encoding essential light chain of human ventricular myosin (ELCv), on the functional properties of cardiac myosin and its isolated head (myosin subfragment 1, S1) were investigated. Only the M149V mutation upregulated the actin-activated ATPase activity of S1. All mutations significantly increased the Ca²⁺-sensitivity of the sliding velocity of thin filaments on the surface with immobilized myosin in the in vitro motility assay, while mutations E56G and M149V (but not E177G) reduced the sliding velocity of regulated thin filaments and F-actin filaments almost twice. Therefore, despite the fact that all studied mutations in ELCv are involved in the development of hypertrophic cardiomyopathy, the mechanisms of their influence on the actin–myosin interaction are different.

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KEY WORDS: myosin, essential light chains, cardiomyopathic mutations, cardiac muscle, molecular mechanism of muscle contraction

DOI: 10.1134/S0006297922110050

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