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.
Baylor College of Medicine, Department of Molecular and Cellular Biology, The Breast Center, Methodist Hospital, Houston, Texas 77030, USA.
Yingchun
Y
Li
Eric C
EC
Chang
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