Protein phosphatase 2A (PP2A) promotes anaphase entry after DNA replication stress in budding yeast

Mol Biol Cell. 2021 Dec 1;32(22):ar36. doi: 10.1091/mbc.E21-04-0222. Epub 2021 Oct 20.

Abstract

DNA replication stress activates the S-phase checkpoint that arrests the cell cycle, but it is poorly understood how cells recover from this arrest. Cyclin-dependent kinase (CDK) and protein phosphatase 2A (PP2A) are key cell cycle regulators, and Cdc55 is a regulatory subunit of PP2A in budding yeast. We found that yeast cells lacking functional PP2ACdc55 showed slow growth in the presence of hydroxyurea (HU), a DNA synthesis inhibitor, without obvious viability loss. Moreover, PP2A mutants exhibited delayed anaphase entry and sustained levels of anaphase inhibitor Pds1 after HU treatment. A DNA damage checkpoint Chk1 phosphorylates and stabilizes Pds1. We show that chk1Δ and mutation of the Chk1 phosphorylation sites in Pds1 largely restored efficient anaphase entry in PP2A mutants after HU treatment. In addition, deletion of SWE1, which encodes the inhibitory kinase for CDK or mutation of the Swe1 phosphorylation site in CDK (cdc28F19), also suppressed the anaphase entry delay in PP2A mutants after HU treatment. Our genetic data suggest that Swe1/CDK acts upstream of Pds1. Surprisingly, cdc55Δ showed significant suppression to the viability loss of S-phase checkpoint mutants during DNA synthesis block. Together, our results uncover a PP2A-Swe1-CDK-Chk1-Pds1 axis that promotes recovery from DNA replication stress.

Publication types

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

MeSH terms

  • Anaphase / genetics*
  • CDC2 Protein Kinase / genetics
  • CDC2 Protein Kinase / metabolism
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Checkpoint Kinase 1 / genetics
  • Checkpoint Kinase 1 / metabolism
  • DNA Replication / drug effects
  • DNA Replication / physiology*
  • Green Fluorescent Proteins / genetics
  • Hydroxyurea / pharmacology
  • Microorganisms, Genetically-Modified
  • Mutation
  • Phosphorylation
  • Protein Phosphatase 2 / genetics
  • Protein Phosphatase 2 / metabolism*
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / metabolism
  • S Phase / genetics
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Securin / genetics
  • Securin / metabolism

Substances

  • CDC55 protein, S cerevisiae
  • Cell Cycle Proteins
  • PDS1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Securin
  • Green Fluorescent Proteins
  • SWE1 protein, S cerevisiae
  • Protein-Tyrosine Kinases
  • Checkpoint Kinase 1
  • CDC2 Protein Kinase
  • PPH21 protein, S cerevisiae
  • Pph22 protein, S cerevisiae
  • Protein Phosphatase 2
  • Hydroxyurea