Role of myosin II tail sequences in its function and localization at the cleavage furrow in Dictyostelium

Cytoplasmic myosin II accumulates in the cleavage furrow and provides the f orce for cytokinesis in animal and amoeboid cells. One model proposes that a specific domain in the myosin II tail is responsible for its localization , possibly by interacting with a factor concentrated in the equatorial regi on. To test this possibility, we have expressed myosins carrying mutations in the tail domain in a strain of Dictyostelium cells from which the endoge nous myosin heavy chain gene has been deleted. The mutations used in this s tudy include four internal tail deletions: My Delta 824-941, My Delta 943-1 464, My Delta 943-1194 and My Delta 1156-1464, Contrary to the prediction o f the hypothesis, immunofluorescence staining demonstrated that all mutant myosins were able to move toward the furrow region. Chimeric myosins, which consisted of a Dictyostelium myosin head and chicken skeletal myosin tail, also efficiently localized to the cleavage furrow All these deletion and c himeric mutant myosins, except for My Delta 943-1464, the largest deletion mutant, were able to support cytokinesis in suspension. Our data suggest th at there is no single specific domain in the tail of Dictyostelium myosin I I that is required for its functioning at and localization to the cleavage furrow.