Efficient chromosome biorientation and the tension checkpoint in saccharomyces cerevisiae both require Bir1

Vasso Makrantoni, Michael J. R. Stark

    Research output: Contribution to journalArticle

    14 Citations (Scopus)

    Abstract

    Accurate chromosome segregation requires the capture of sister kinetochores by microtubules from opposite spindle poles prior to the initiation of anaphase, a state termed chromosome biorientation. In the budding yeast Saccharomyces cerevisiae, the conserved protein kinase Ipl1 (Aurora B in metazoans) is critical for ensuring correct chromosomal alignment. Ipl1 associates with its activators Sli15 (INCENP), Nbl1 (Borealin), and Bir1 (Survivin), but while Sli15 clearly functions with Ipl1 to promote chromosome biorientation, the role of Bir1 has been uncertain. Using a temperature-sensitive bir1 mutant (bir1-17), we show that Bir1 is needed to permit efficient chromosome biorientation. However, once established, chromosome biorientation is maintained in bir1-17 cells at the restrictive temperature. Ipl1 is partially delocalized in bir1-17 cells, and its protein kinase activity is markedly reduced under nonpermissive conditions. bir1-17 cells arrest normally in response to microtubule depolymerization but fail to delay anaphase when sister kinetochore tension is reduced. Thus, Bir1 is required for the tension checkpoint. Despite their robust mitotic arrest in response to nocodazole, bir1-17 cells are hypersensitive to microtubule-depolymerizing drugs and show a more severe biorientation defect on recovery from nocodazole treatment. The role of Bir1 therefore may become more critical when spindle formation is delayed.

    Original languageEnglish
    Pages (from-to)4552-4562
    Number of pages11
    JournalMolecular and Cellular Biology
    Volume29
    Issue number16
    DOIs
    Publication statusPublished - 15 Aug 2009

    Keywords

    • SPINDLE CHECKPOINT
    • PROTEIN-KINASE
    • BUDDING YEAST
    • MITOTIC SPINDLE
    • AURORA-B
    • COMPLEX
    • PHOSPHORYLATION
    • ANAPHASE
    • KINETOCHORES
    • SEGREGATION

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