Schizosaccharomyces pombe Ras1 effector, Scd1, interacts with Klp5 and Klp6 kinesins to mediate cytokinesis.
Fission yeast Scd1 is an exchange factor for Cdc42 and an effector of Ras1. In a screen for scd1 interacting genes, we isolated klp5 and klp6, which encode presumptive kinesins. Klp5 and Klp6 form a complex to control the same processes, which so far include microtubule dynamics and chromosome segregation. We showed that klp5 or klp6 inactivation in combination with the scd1 deletion (scd1delta) created a synthetic temperature-dependent growth defect. Further genetic analysis demonstrated that Klp5 and Klp6 interacted specifically with the Ras1-Scd1 pathway, but not with the Ras1-Byr2 pathway. In addition, Klp5 and Klp6 can stably associate with Scd1 and Cdc42. A deletion in the Scd1 C terminus, which contains the PB1 domain, prevented Scd1 binding to Klp5/6 and caused a growth defect in Klp5/6 mutant cells that is indistinguishable from that induced by scd1delta. Analysis of the double-mutant phenotype indicated that at the nonpermissive temperature, cells failed to undergo cytokinesis efficiently. These cells contained abnormal contractile rings in which F-actin and Mid1, a key regulator of F-actin ring formation and positioning, are mispositioned and fragmented. These data suggest that Klp5/6 cooperate with the Ras1-Scd1 pathway to influence proper formation of the contractile ring for cytokinesis.
Li
Yingchun
Y
Baylor College of Medicine, Department of Molecular and Cellular Biology, The Breast Center, Methodist Hospital, Houston, Texas 77030, USA.
Chang
Eric C
EC
D000199:Actins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology; D019204:GTP-Binding Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000166:cytology / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D018631:ras Proteins
D000199:Actins; D018797:Cell Cycle Proteins; D020662:Guanine Nucleotide Exchange Factors; D008869:Microtubule-Associated Proteins; D011518:Proto-Oncogene Proteins; D029702:Schizosaccharomyces pombe Proteins; C089769:scd1 protein, S pombe; C077892:BYR2 protein, S pombe; D020930:MAP Kinase Kinase Kinases; D019204:GTP-Binding Proteins; C469734:Klp5 protein, S pombe; C459102:Klp6 protein, S pombe; D016547:Kinesins; C492657:Ras1 protein, S pombe; D018631:ras Proteins