Repression of yeast RNA polymerase III by stress leads to ubiquitylation and proteasomal degradation of its largest subunit, C160

Biochim Biophys Acta Gene Regul Mech. 2019 Jan;1862(1):25-34. doi: 10.1016/j.bbagrm.2018.10.007. Epub 2018 Oct 19.

Abstract

Respiratory growth and various stress conditions repress RNA polymerase III (Pol III) transcription in Saccharomyces cerevisiae. Here we report a degradation of the largest Pol III catalytic subunit, C160 as a consequence of Pol III transcription repression. We observed C160 degradation in response to transfer of yeast from fermentation to respiration conditions, as well as treatment with rapamycin or inhibition of nucleotide biosynthesis. We also detected ubiquitylated forms of C160 and demonstrated that C160 protein degradation is dependent on proteasome activity. A comparable time-course study of Pol III repression upon metabolic shift from fermentation to respiration shows that the transcription inhibition is correlated with Pol III dissociation from chromatin but that the degradation of C160 subunit is a downstream event. Despite blocking degradation of C160 by proteasome, Pol III-transcribed genes are under proper regulation. We postulate that the degradation of C160 is activated under stress conditions to reduce the amount of existing Pol III complex and prevent its de novo assembly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Proteasome Endopeptidase Complex / metabolism
  • Protein Subunits / metabolism*
  • RNA Polymerase III / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / physiology
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Stress, Physiological / physiology*
  • Transcription, Genetic
  • Ubiquitination

Substances

  • Protein Subunits
  • Saccharomyces cerevisiae Proteins
  • RNA Polymerase III
  • Proteasome Endopeptidase Complex