Endonucleolytic cleavage in the expansion segment 7 of 25S rRNA is an early marker of low-level oxidative stress in yeast

J Biol Chem. 2017 Nov 10;292(45):18469-18485. doi: 10.1074/jbc.M117.800003. Epub 2017 Sep 22.

Abstract

The ability to detect and respond to oxidative stress is crucial to the survival of living organisms. In cells, sensing of increased levels of reactive oxygen species (ROS) activates many defensive mechanisms that limit or repair damage to cell components. The ROS-signaling responses necessary for cell survival under oxidative stress conditions remain incompletely understood, especially for the translational machinery. Here, we found that drug treatments or a genetic deficiency in the thioredoxin system that increase levels of endogenous hydrogen peroxide in the yeast Saccharomyces cerevisiae promote site-specific endonucleolytic cleavage in 25S ribosomal RNA (rRNA) adjacent to the c loop of the expansion segment 7 (ES7), a putative regulatory region located on the surface of the 60S ribosomal subunit. Our data also show that ES7c is cleaved at early stages of the gene expression program that enables cells to successfully counteract oxidative stress and is not a prerequisite or consequence of apoptosis. Moreover, the 60S subunits containing ES7c-cleaved rRNA cofractionate with intact subunits in sucrose gradients and repopulate polysomes after a short starvation-induced translational block, indicating their active role in translation. These results demonstrate that ES7c cleavage in rRNA is an early and sensitive marker of increased ROS levels in yeast cells and suggest that changes in ribosomes may be involved in the adaptive response to oxidative stress.

Keywords: RNA degradation; RNA structure; Saccharomyces cerevisiae; oxidation-reduction (redox); oxidative stress; reactive oxygen species (ROS); redox signaling; ribosomal ribonucleic acid (rRNA) (ribosomal RNA); ribosome; stress response.

MeSH terms

  • Apoptosis / drug effects
  • Biomarkers / metabolism
  • Gene Deletion
  • Gene Expression Regulation, Fungal* / drug effects
  • Hormesis
  • Kinetics
  • Nucleic Acid Conformation
  • Oxidants / pharmacology
  • Oxidative Stress* / drug effects
  • Peroxidases / genetics
  • Peroxidases / metabolism
  • Polyribosomes / drug effects
  • Polyribosomes / enzymology*
  • Polyribosomes / metabolism
  • RNA Cleavage / drug effects
  • RNA Stability / drug effects
  • RNA, Fungal / chemistry
  • RNA, Fungal / metabolism*
  • RNA, Ribosomal / chemistry
  • RNA, Ribosomal / metabolism*
  • Reactive Oxygen Species / agonists
  • Reactive Oxygen Species / antagonists & inhibitors
  • Reactive Oxygen Species / metabolism*
  • Reducing Agents / pharmacology
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / physiology
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Spheroplasts / drug effects
  • Spheroplasts / enzymology
  • Spheroplasts / growth & development
  • Spheroplasts / physiology
  • Unfolded Protein Response / drug effects

Substances

  • Biomarkers
  • Oxidants
  • RNA, Fungal
  • RNA, Ribosomal
  • Reactive Oxygen Species
  • Reducing Agents
  • Saccharomyces cerevisiae Proteins
  • RNA, ribosomal, 25S
  • Peroxidases
  • Tsa1 protein, S cerevisiae