Pseudo-acetylation of actin K326 and K328 increases duration and force of contraction in mouse cardiomyocytes

Abstract

Myosin motors bind to F-actin-based thin filaments to generate muscle force, but under relaxed conditions these binding sites are sterically blocked by tropomyosin. During muscle activation, calcium binding to the troponin complex alters the position of tropomyosin such that myosin heads can bind to actin and initiate muscle contraction. The location of tropomyosin along F-actin is partially determined by electrostatic interactions. In particular, positively charged lysine residues K326 and K328 along the actin filament form highly favorable electrostatic contacts with tropomyosin, which along with troponin are critical for establishing its inhibitory binding position.