Spindle alignment regulates the dynamic association of checkpoint proteins with yeast spindle pole bodies.
In many polarized cells, the accuracy of chromosome segregation depends on the correct positioning of the mitotic spindle. In budding yeast, the spindle positioning checkpoint (SPOC) delays mitotic exit when the anaphase spindle fails to extend toward the mother-daughter axis. However it remains to be established how spindle orientation is translated to SPOC components at the yeast spindle pole bodies (SPB). Here, we used photobleaching techniques to show that the dynamics with which Bub2-Bfa1 turned over at SPBs significantly increased upon SPOC activation. A version of Bfa1 that was stably associated with SPBs rendered the cells SPOC deficient without affecting other Bub2-Bfa1 functions, demonstrating the functional importance of regulating the dynamics of Bfa1 SPB association. In addition, we established that the SPOC kinase Kin4 is the major regulator of Bfa1 residence time at SPBs. We suggest that upon SPOC activation Bfa1-Bub2 spreads throughout the cytoplasm, thereby inhibiting mitotic exit.
Caydasi
Ayse Koca
AK
DKFZ-ZMBH Alliance, German Cancer Research Centre (DKFZ), Heidelberg, Germany.
Pereira
Gislene
G
D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D008870:Microtubules / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism* / Q000648:ultrastructure
C119117:BFA1 protein, S cerevisiae; C070351:BUB2 protein, S cerevisiae; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C503719:KIN4 kinase, S cerevisiae; D017346:Protein Serine-Threonine Kinases