The Yeast DNA Damage Checkpoint Kinase Rad53 Targets the Exoribonuclease, Xrn1

G3 (Bethesda). 2018 Dec 10;8(12):3931-3944. doi: 10.1534/g3.118.200767.


The highly conserved DNA damage response (DDR) pathway monitors the genomic integrity of the cell and protects against genotoxic stresses. The apical kinases, Mec1 and Tel1 (ATR and ATM in human, respectively), initiate the DNA damage signaling cascade through the effector kinases, Rad53 and Chk1, to regulate a variety of cellular processes including cell cycle progression, DNA damage repair, chromatin remodeling, and transcription. The DDR also regulates other cellular pathways, but direct substrates and mechanisms are still lacking. Using a mass spectrometry-based phosphoproteomic screen in Saccharomyces cerevisiae, we identified novel targets of Rad53, many of which are proteins that are involved in RNA metabolism. Of the 33 novel substrates identified, we verified that 12 are directly phosphorylated by Rad53 in vitro: Xrn1, Gcd11, Rps7b, Ded1, Cho2, Pus1, Hst1, Srv2, Set3, Snu23, Alb1, and Scp160. We further characterized Xrn1, a highly conserved 5' exoribonuclease that functions in RNA degradation and the most enriched in our phosphoproteomics screen. Phosphorylation of Xrn1 by Rad53 does not appear to affect Xrn1's intrinsic nuclease activity in vitro, but may affect its activity or specificity in vivo.

Keywords: DNA Damage Response; Rad53; Xrn1; checkpoint; phosphoproteomics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Checkpoint Kinase 2 / genetics
  • Checkpoint Kinase 2 / metabolism*
  • DNA Damage / physiology
  • DNA Repair / physiology
  • Exoribonucleases / genetics
  • Exoribonucleases / metabolism
  • Phosphorylation / physiology
  • RNA Stability / physiology*
  • RNA, Fungal / genetics
  • RNA, Fungal / metabolism*
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Substrate Specificity / physiology


  • Cell Cycle Proteins
  • RNA, Fungal
  • Saccharomyces cerevisiae Proteins
  • Checkpoint Kinase 2
  • RAD53 protein, S cerevisiae
  • Exoribonucleases
  • XRN1 protein, S cerevisiae

Associated data

  • figshare/10.25387/g3.7176383