Pop2 phosphorylation at S39 contributes to the glucose repression of stress response genes, HSP12 and HSP26

PLoS One. 2019 Apr 11;14(4):e0215064. doi: 10.1371/journal.pone.0215064. eCollection 2019.


The S. cerevisiae Pop2 protein is an exonuclease in the Ccr4-Not complex that is a conserved regulator of gene expression. Pop2 regulates gene expression post-transcriptionally by shortening the poly(A) tail of mRNA. A previous study has shown that Pop2 is phosphorylated at threonine 97 (T97) by Yak1 protein kinase in response to glucose limitation. However, the physiological importance of Pop2 phosphorylation remains unknown. In this study, we found that Pop2 is phosphorylated at serine 39 (S39) under unstressed conditions. The dephosphorylation of S39 was occurred rapidly after glucose depletion, and the addition of glucose to the glucose-deprived culture recovered this phosphorylation, suggesting that Pop2 phosphorylation at S39 is regulated by glucose. This glucose-regulated phosphorylation of Pop2 at S39 is dependent on Pho85 kinase. We previously reported that Pop2 takes a part in the cell wall integrity pathway by regulating LRG1 mRNA; however, S39 phosphorylation of Pop2 is not involved in LRG1 expression. On the other hand, Pop2 phosphorylation at S39 is involved in the expression of HSP12 and HSP26, which encode a small heat shock protein. In the medium supplemented with glucose, Pop2 might be phosphorylated at S39 by Pho85 kinase, and this phosphorylation contributes to repress the expression of HSP12 and HSP26. Glucose starvation inactivated Pho85, which resulted in the derepression of HSP12 and HSP26, together with other glucose sensing mechanisms. Our results suggest that Pho85-dependent phosphorylation of Pop2 is a part of the glucose sensing system in yeast.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catabolite Repression
  • GTPase-Activating Proteins / genetics
  • GTPase-Activating Proteins / metabolism
  • Gene Expression Regulation, Fungal / drug effects*
  • Glucose / pharmacology*
  • Glycoproteins / genetics
  • Glycoproteins / metabolism
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism*
  • Phosphorylation
  • Ribonucleases / genetics
  • Ribonucleases / metabolism*
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Serine / chemistry
  • Serine / metabolism*


  • GTPase-Activating Proteins
  • Glycoproteins
  • HSP12 protein, S cerevisiae
  • HSP26 protein, S cerevisiae
  • Heat-Shock Proteins
  • LRG1 protein, S cerevisiae
  • Pir3 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Serine
  • Ribonucleases
  • POP2 protein, S cerevisiae
  • Glucose

Grants and funding

This research was supported by JSPS KAKENHI Grant Numbers 15K06944 and 18K06053 (to K.I.).