title: Bub3 promotes Cdc20-dependent activation of the APC/C in S. cerevisiae.
abstract: The spindle checkpoint ensures accurate chromosome segregation by sending a signal from an unattached kinetochore to inhibit anaphase onset. Numerous studies have described the role of Bub3 in checkpoint activation, but less is known about its functions apart from the spindle checkpoint. In this paper, we demonstrate that Bub3 has an unexpected role promoting metaphase progression in budding yeast. Loss of Bub3 resulted in a metaphase delay that was not a consequence of aneuploidy or the activation of a checkpoint. Instead, bub3Δ cells had impaired binding of the anaphase-promoting complex/cyclosome (APC/C) with its activator Cdc20, and the delay could be rescued by Cdc20 overexpression. Kinetochore localization of Bub3 was required for normal mitotic progression, and Bub3 and Cdc20 colocalized at the kinetochore. Although Bub1 binds Bub3 at the kinetochore, bub1Δ cells did not have compromised APC/C and Cdc20 binding. The results demonstrate that Bub3 has a previously unknown function at the kinetochore in activating APC/C-Cdc20 for normal mitotic progression.
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405.
authors.forename: Dai
authors.initials: D
authors.lastname: Tsuchiya
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405 sonil@indiana.edu.
authors.forename: Soni
authors.initials: S
authors.lastname: Lacefield
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome / Q000378:metabolism*; D064199:Cdc20 Proteins / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000502:physiology*; D008938:Mitosis; D011485:Protein Binding; D021381:Protein Transport; D059748:Proteolysis; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*
chemical_list: C070352:BUB3 protein, S cerevisiae; C577495:CDC20 protein, S cerevisiae; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D029701:Saccharomyces cerevisiae Proteins; D064173:Anaphase-Promoting Complex-Cyclosome