Myosin-II Tails Confer Unique Functions in Schizosaccharomyces pombe: Characterization of a Novel Myosin-II Tail

AUTOR(ES)

Bezanilla, Magdalena

FONTE

The American Society for Cell Biology

RESUMO

Schizosaccharomyces pombe has two myosin-IIs, Myo2p and Myp2p, which both concentrate in the cleavage furrow during cytokinesis. We studied the phenotype of mutant myosin-II strains to examine whether these myosins have overlapping functions in the cell. myo2+ is essential. myp2+ cannot rescue loss of myo2+ even at elevated levels of expression. myp2+ is required under specific nutritional conditions; thus myo2+ cannot rescue under these conditions. Studies with chimeras show that the tails rather than the structurally similar heads determine the gene-specific functions of myp2+ and myo2+. The Myo2p tail is a rod-shaped coiled-coil dimer that aggregates in low salt like other myosin-II tails. The Myp2p tail is monomeric in high salt and is insoluble in low salt. Biophysical properties of the full-length Myp2p tail and smaller subdomains indicate that two predicted coiled-coil regions fold back on themselves to form a rod-shaped antiparallel coiled coil. This suggests that Myp2p is the first type II myosin with only one head. The C-terminal two-thirds of Myp2p tail are essential for function in vivo and may interact with components of the salt response pathway.

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