Analysis of kinesin motor function at budding yeast kinetochores.
Accurate chromosome segregation during mitosis requires biorientation of sister chromatids on the microtubules (MT) of the mitotic spindle. Chromosome-MT binding is mediated by kinetochores, which are multiprotein structures that assemble on centromeric (CEN) DNA. The simple CENs of budding yeast are among the best understood, but the roles of kinesin motor proteins at yeast kinetochores have yet to be determined, despite evidence of their importance in higher eukaryotes. We show that all four nuclear kinesins in Saccharomyces cerevisiae localize to kinetochores and function in three distinct processes. Kip1p and Cin8p, which are kinesin-5/BimC family members, cluster kinetochores into their characteristic bilobed metaphase configuration. Kip3p, a kinesin-8,-13/KinI kinesin, synchronizes poleward kinetochore movement during anaphase A. The kinesin-14 motor Kar3p appears to function at the subset of kinetochores that become detached from spindle MTs. These data demonstrate roles for structurally diverse motors in the complex processes of chromosome segregation and reveal important similarities and intriguing differences between higher and lower eukaryotes.
Tytell
Jessica D
JD
Department of Biology and 2Biological Engineering Division Massachusetts Institute of Technology Cambridge MA 02139, USA.
Sorger
Peter K
PK
D020090:Chromosome Segregation / Q000502:physiology*; D019143:Evolution, Molecular; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D016547:Kinesins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018386:Kinetochores / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D020409:Molecular Motor Proteins / Q000502:physiology*; D009154:Mutation / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D013045:Species Specificity; D008941:Spindle Apparatus
C075342:CIN8 protein, S cerevisiae; C063504:KAR3 protein, S cerevisiae; C431747:KIP1 protein, S cerevisiae; C108256:KIP3 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D020409:Molecular Motor Proteins; D029701:Saccharomyces cerevisiae Proteins; D016547:Kinesins