Myosins

Allosteric inhibition of myosin by phenamacril: a synergistic mechanism revealed by computational and experimental approaches

“…The stabilized closed configuration and enhanced binding affinity of substrate ATP (especially its γ‐phosphate) might trap the hydrolysis products inside the pocket. Additionally, consistent with a previous study, 32 the observed weakened swing of CLD and widened actin‐binding cleft should also disfavor the transition of nucleotide state (from ATP to ADP) and subsequent cascade. Cooperating with reduced inter‐ and intra‐subdomain coupling, the allosteric inhibitor grasps the FgMyoI in the pre‐power stroke stage and hinders it from reaching the reprimed state and proceeding the upcoming power stroke stage.…”

“…From the free‐energy surface, the holo‐ATP form maintains the broadest conformational sampling space and moves along negative PC1, which involves the motion of the swing of the CLD, suggesting that the nucleotide‐binding increases the conformational flexibility as observed in RMSF profiles and might stimulate the movement of the myosin CLD. This kind of movement is necessary for the hydrolysis of nucleotides 32 . While the presence of phenamacril effectively inhibits the oscillation of the CLD.…”

“…The relatively active dynamic configuration of CLD when ATP binds to the catalytic center is essential for ATP hydrolysis during the repriming stage of the recovery stroke 32 . In contrast, the movement of CLD was substantially restricted in the presence of PHA, reporting on a stable ‘up’ configuration with CLD coming closer to the N‐terminus of the U50 domain.…”

“…Acting as an activator of myosin, actin binds to myosin and catalyzes the essential hydrolysis release step 36 . The closure of the outer cleft during the post‐recovery stroke and the conformational transition of the actin‐binding interface are critical for the actomyosin cycle to proceed 32 . At the beginning of ATPase cycle, the electrostatic interaction between the myosin HCM loop and the charged actin N‐terminus initiates the weak binding of myosin with actin and Pi release, 36 which confines the motor on actin and promotes the subsequent PPI, such as those between loop2/loop3 and the actin surface.…”