Mutational analysis of phosphorylation sites in the Dictyostelium myosin II tail: disruption of myosin function by a single charge change

The dynamic assembly/disassembly of non-muscle myosin II filaments is criti cal for the regulation of enzymatic activities and localization, Phosphoryl ation of three threonines, 1823, 1833 and 2029, in the tail of Dictyosteliu m discoideum myosin II has been implicated in control of myosin filament as sembly. By systematically replacing the three threonines to aspartates, mim icking a phosphorylated residue, we found that position 1823 is the most cr itical one for the regulation of myosin filament formation and in vivo func tion, Surprisingly, a single charge change is able to perturb filament form ation and in vivo function of myosin II. (C) 2000 Federation of European Bi ochemical Societies.