Characterization of short ADP ribosylated oligomers developed by modification in F-actin structure

Researchers have been trying to determine the mechanism of the crossbridge cycle, containing actomyosin complex, formed by the interaction of F-actin and myosin. But, because actin forms polymers of varying lengths, it has been difficult to crystallize this complex. My research is aimed at developing a homogeneous actomyosin complex with a short actin oligomer that possesses one myosin-binding site. ADPr-oligomers are produced by chemical crosslinking of F-actin and inhibiting polymerization by ADP-ribosylation. Specifically, I determined the behavior of an ADPr-trimer and dimer with myosin and its effect on actomyosin activity. Individual myosin ATPase activities of ADPr-trimer/dimer were similar to basal myosin activity. However, in the presence of long ADPr-oligomers (tetramer, pentamer, etc.) or F-actin, ADPr-dimer/trimer show binding and activity with myosin thick filaments. Thus, I was unable to produce a short actomyosin complex through these efforts and present a model for interaction of short actin oligomers with each other in the presence of long actin filaments and myosin.