The polo-box-dependent induction of ectopic septal structures by a mammalian polo kinase, plk, in Saccharomyces cerevisiae.
Members of the polo subfamily of protein kinases play pivotal roles in cell-cycle control and proliferation. In addition to a high degree of sequence similarity in the kinase domain, polo kinases contain a strikingly conserved motif termed "polo-box" in the noncatalytic C-terminal domain. We have previously shown that the mammalian polo-like kinase Plk is a functional homolog of Saccharomyces cerevisiae Cdc5. Here, we show that, in a polo-box- and kinase activity-dependent manner, ectopic expression of Plk in budding yeast can induce a class of cells with abnormally elongated buds. In addition to localization at spindle poles and cytokinetic neck filaments, Plk induces and localizes to ectopic septin ring structures within the elongated buds. In contrast, mutations in the polo-box abolish both localization to, and induction of, septal structures. Consistent with the polo-box-dependent subcellular localization, the C-terminal domain of Plk, but not its polo-box mutant, is sufficient for subcellular localization. Our data suggest that Plk may contribute a signal to initiate or promote cytokinetic event(s) and that an intact polo-box is required for regulation of these cellular processes.
Lee
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Laboratory of Metabolism, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Building 37, Room 3D25, Bethesda, MD 20892, USA.
Song
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Erikson
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D000199:Actins / Q000737:chemistry; D020816:Amino Acid Motifs; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000502:physiology; D029721:Drosophila Proteins; D009154:Mutation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000502:physiology*; D016601:RNA-Binding Proteins; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins
D000199:Actins; C513239:CEF1 protein, S cerevisiae; D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases