Establishing biorientation occurs with precocious separation of the sister kinetochores, but not the arms, in the early spindle of budding yeast.
Sister kinetochores are bioriented toward the spindle poles in higher eukaryotic prometaphase before chromosome segregation. We show that, in budding yeast, the sister kinetochores are separated in the very early spindle, while the sister arms remain associated. Biorientation of the separated kinetochores is achieved already after replication. Mtw1p, a homolog of fission yeast Mis12 required for biorientation, locates at the centromeres in an Ndc10p-dependent manner. Mtw1p and the sequences 1.8 and 3.8 kb from CEN3 and CEN15, respectively, behave like the precociously separated kinetochores, whereas the sequences 23 and 35 kb distant from CEN3 and CEN5 previously used as the centromere markers behave like a part of the arm. Mtw1p and Ndc10p are identically located except for additional spindle localization of Ndc10p. A model explaining small centromeres and early spindle formation in budding yeast is proposed.
Goshima
G
G
CREST Research Project, Department of Biophysics, Graduate School of Science, Kyoto University, Japan.
Yanagida
M
M
D000970:Antineoplastic Agents / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D002470:Cell Survival / Q000502:physiology; D020090:Chromosome Segregation / Q000187:drug effects / Q000502:physiology; D015825:Chromosomes, Fungal / Q000502:physiology; D003116:Color; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics; D005656:Fungal Proteins / Q000032:analysis / Q000235:genetics; D006918:Hydroxyurea / Q000494:pharmacology; D018386:Kinetochores / Q000502:physiology*; D008677:Metaphase / Q000235:genetics; D008870:Microtubules / Q000737:chemistry / Q000235:genetics; D016296:Mutagenesis / Q000502:physiology; D015739:Nocodazole / Q000494:pharmacology; D021382:Protein Sorting Signals / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000166:cytology* / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D008941:Spindle Apparatus / Q000502:physiology*; D013194:Staining and Labeling; D013696:Temperature
D000970:Antineoplastic Agents; C081071:CBF2 protein, S cerevisiae; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C120362:MTW1 protein, S cerevisiae; D021382:Protein Sorting Signals; D029701:Saccharomyces cerevisiae Proteins; D015739:Nocodazole; D006918:Hydroxyurea