Yeast Fin1-PP1 dephosphorylates an Ipl1 substrate, Ndc80, to remove Bub1-Bub3 checkpoint proteins from the kinetochore during anaphase

PLoS Genet. 2021 May 25;17(5):e1009592. doi: 10.1371/journal.pgen.1009592. eCollection 2021 May.

Abstract

The spindle assembly checkpoint (SAC) prevents anaphase onset in response to chromosome attachment defects, and SAC silencing is essential for anaphase onset. Following anaphase onset, activated Cdc14 phosphatase dephosphorylates the substrates of cyclin-dependent kinase to facilitate anaphase progression and mitotic exit. In budding yeast, Cdc14 dephosphorylates Fin1, a regulatory subunit of protein phosphatase 1 (PP1), to enable kinetochore localization of Fin1-PP1. We previously showed that kinetochore-localized Fin1-PP1 promotes the removal of the SAC protein Bub1 from the kinetochore during anaphase. We report here that Fin1-PP1 also promotes kinetochore removal of Bub3, the Bub1 partner, but has no effect on another SAC protein Mad1. Moreover, the kinetochore localization of Bub1-Bub3 during anaphase requires Aurora B/Ipl1 kinase activity. We further showed that Fin1-PP1 facilitates the dephosphorylation of kinetochore protein Ndc80, a known Ipl1 substrate. This dephosphorylation reduces kinetochore association of Bub1-Bub3 during anaphase. In addition, we found that untimely Ndc80 dephosphorylation causes viability loss in response to tensionless chromosome attachments. These results suggest that timely localization of Fin1-PP1 to the kinetochore controls the functional window of SAC and is therefore critical for faithful chromosome segregation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anaphase*
  • Aurora Kinases / metabolism*
  • Cell Cycle Proteins / metabolism*
  • Chromosome Segregation
  • Cytoskeletal Proteins / metabolism*
  • Kinetochores / chemistry
  • Kinetochores / drug effects
  • Kinetochores / metabolism*
  • Microbial Viability / genetics
  • Mutation
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / deficiency
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phosphorylation
  • Protein Phosphatase 1 / metabolism*
  • Protein Serine-Threonine Kinases / metabolism*
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae* / cytology
  • Saccharomyces cerevisiae* / enzymology
  • Saccharomyces cerevisiae* / metabolism
  • Spindle Apparatus / drug effects
  • Time Factors

Substances

  • BUB3 protein, S cerevisiae
  • Bub1 protein, S cerevisiae
  • Cell Cycle Proteins
  • Cytoskeletal Proteins
  • FIN1 protein, S cerevisiae
  • NDC80 protein, S cerevisiae
  • Nuclear Proteins
  • Saccharomyces cerevisiae Proteins
  • Aurora Kinases
  • IPL1 protein, S cerevisiae
  • Protein Serine-Threonine Kinases
  • Protein Phosphatase 1