The K130L myosin mutation in Dictyostelium maintained normal ATPase and motile activities but exhibited a 4-fold increase in Km for ATP compared to wild-type myosin.
Does the K130L mutation in the myosin motor domain alter the enzymatic or motile activities of myosin in a Dictyostelium model?
The highly conserved Lys-130 residue in the myosin motor domain is not essential for enzymatic or motile activities but plays a role in the interaction with ATP.
Effect estimate: 4-fold increase in Km
We have created a mutant Dictyostelium myosin II heavy chain gene in which a highly conserved lysine residue (Lys-130) is changed to leucine. Lys-130 is a residue that is known to be trimethylated in skeletal muscle myosin and had been thought to play an integral role in the interaction of myosin with ATP during the actomyosin chemomechanical cycle. We report here the first in vivo and in vitro characterization of an engineered missense mutation in the motor domain of myosin. Expression of the K130L myosin in a Dictyostelium strain that lacks the myosin II heavy chain gene is sufficient to restore the ability of that cell line to undergo cytokinesis and multicellular development, processes that require functional myosin. The K130L myosin purified from these cells displays maximal actin-activated ATPase activities and promotes maximal sliding velocities of actin filaments in an in vitro motility assay that are comparable with those of wild-type myosin. These results demonstrate that this lysine residue is not required for the enzymatic or motile activities of myosin. However, the mutant protein exhibits a 4-fold increase in Km for ATP over wild-type myosin, indicating that this residue participates in the interaction of myosin with its nucleotide substrate.
Ruppel et al. (Fri,) reported a other. K130L myosin mutation vs. Wild-type myosin was evaluated on Enzymatic or motile activities and Km for ATP (4-fold increase in Km). The K130L myosin mutation in Dictyostelium maintained normal ATPase and motile activities but exhibited a 4-fold increase in Km for ATP compared to wild-type myosin.