F-ACTIN DISTRIBUTION OF DICTYOSTELIUM MYOSIN-I DOUBLE MUTANTS

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.