F-actin distribution of Dictyostelium myosin I double mutants

ABSTRACT The roles of the myosin I class of mechanoenzymes have been investigated by single and double gene knockout studies in the amoeba Dictyostelium discoideum. Cells lacking different myosin I pairs (myoA‐/myoB‐, myoB‐/myoC‐, and myoA‐/myoC‐) were examined with respect to their cytoskeletal organization. F‐actin localization by rhodamine‐phalloidin staining of cells indicates that the myoA‐/myoB‐, myoB‐/myoC‐, and myoA‐/myoC‐ cells appear to redistribute their F‐actin more slowly than wild type cells upon adhesion to a substrate. These studies suggest that Dictyostelium myoA, myoB, and myoC may have overlapping roles in maintaining the integrity or organization of the cortical membrane cytoskeleton.