Bub1 is essential for assembly of the functional inner centromere.
During mitosis, the inner centromeric region (ICR) recruits protein complexes that regulate sister chromatid cohesion, monitor tension, and modulate microtubule attachment. Biochemical pathways that govern formation of the inner centromere remain elusive. The kinetochore protein Bub1 was shown to promote assembly of the outer kinetochore components, such as BubR1 and CENP-F, on centromeres. Bub1 was also implicated in targeting of Shugoshin (Sgo) to the ICR. We show that Bub1 works as a master organizer of the ICR. Depletion of Bub1 from Xenopus laevis egg extract or from HeLa cells resulted in both destabilization and displacement of chromosomal passenger complex (CPC) from the ICR. Moreover, soluble Bub1 controls the binding of Sgo to chromatin, whereas the CPC restricts loading of Sgo specifically onto centromeres. We further provide evidence that Bub1 kinase activity is pivotal for recruitment of all of these components. Together, our findings demonstrate that Bub1 acts at multiple points to assure the correct kinetochore formation.
Boyarchuk
Yekaterina
Y
Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Salic
Adrian
A
Dasso
Mary
M
Arnaoutov
Alexei
A
D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism* / Q000648:ultrastructure; D020090:Chromosome Segregation / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008297:Male; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D008938:Mitosis / Q000502:physiology*; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D013094:Spermatozoa; D008941:Spindle Apparatus / Q000378:metabolism / Q000648:ultrastructure; D014981:Xenopus
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C496644:SGO1 protein, human; D011494:Protein Kinases; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases