Dictyostelium myosin II as a model to study the actin–myosin interactions during force generation

摘要: During steady-state ATP hydrolysis by actomyosin, myosin cyclically passes through strong actin-binding states and weak states, depending on the nature of a nucleotide in ATPase site. This cyclic change actin-myosin affinity is coupled with lever-arm swing critical for sliding motion force generation actomyosin. To understand structure-function relationship this ATPase-dependent interaction, Dictyostelium II has been extensively used site-directed mutagenesis. By generating large number mutant myosins, two hydrophobic sites have revealed, located at tip upper lower 50 K subdomains myosin, one which 'cardiomyopathy loop'. Furthermore, slight relative orientation these around 'strut loop' shown to work as switch turn off binding actin. Once turned off, enters weak-binding state, where ionic interactions between actin 'loop 2' become dominant maintain association. The details revealed system can serve framework further examinations superfamily proteins.