The E93K mutation of the Act88F gene affected in vitro motility of F-actin and myosin binding, supporting the proposal that actin residue Glu93 is part of the secondary myosin binding site.
Does the E93K mutation in Drosophila Act88F actin affect myosin binding and motility?
The E93K mutation in actin residue Glu93 affects myosin binding, supporting its role in the secondary myosin binding site.
Many mutants have been described that affect the function of the actin encoded by the Drosophila melanogaster indirect flight muscle-specific actin gene, Act88F. We describe the development of procedures for purification of this actin from the other isoforms expressed in the fly as well as in vitro motility, single molecule force/displacement measurements, and stop-flow solution kinetic studies of the wild-type actin and that of the E93K mutation of the Act88F gene. We show that this mutation affects in vitro motility of F-actin, in both the presence and absence of methylcellulose, and the ability of the ACT88F actin to bind the S1 fragment of rabbit skeletal myosin. However, optical tweezer measurements of the actomyosin working stroke and the force transmitted from the rabbit heavy meromyosin to and through F-actin are unchanged by the mutation. These results support the proposal (Holmes, K. C. (1995) Biophys J. 68, (suppl.) 2-7) that actin residue Glu(93) is part of the secondary myosin binding site and suggest that myosin binding occurs first at the primary myosin binding site and then at the secondary site.
Razzaq et al. (Fri,) reported a other. E93K mutation of the Act88F gene vs. Wild-type actin was evaluated on In vitro motility of F-actin and ability to bind the S1 fragment of rabbit skeletal myosin. The E93K mutation of the Act88F gene affected in vitro motility of F-actin and myosin binding, supporting the proposal that actin residue Glu93 is part of the secondary myosin binding site.
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