Myosin-II tails confer unique functions in Schizosaccharomyces pombe: characterization of a novel myosin-II tail.
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.
Bezanilla
M
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Biochemistry Cellular and Molecular Biology Graduate Program, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Pollard
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TD
D000818:Animals; D001665:Binding Sites; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D018995:Myosin Heavy Chains; D024462:Myosin Type II; D024701:Myosin Type V; D009218:Myosins / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000235:genetics / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins
D005656:Fungal Proteins; C077512:MYO2 protein, S cerevisiae; C434211:MYO2 protein, S pombe; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D024462:Myosin Type II; D024701:Myosin Type V; D018995:Myosin Heavy Chains; D009218:Myosins