Document Type

Article

Version Deposited

Published Version

Publication Date

9-14-2018

Publication Title

The Journal of Biological Chemistry

DOI

10.1074/jbc.RA118.004174

Abstract

Stress-induced strand breaks in rRNA have been observed in many organisms, but the mechanisms by which they originate are not well-understood. Here we show that a chemical rather than an enzymatic mechanism initiates rRNA cleavages during oxidative stress in yeast (Saccharomyces cerevisiae). We used cells lacking the mitochondrial glutaredoxin Grx5 to demonstrate that oxidant-induced cleavage formation in 25S rRNA correlates with intracellular iron levels. Sequestering free iron by chemical or genetic means decreased the extent of rRNA degradation and relieved the hypersensitivity of grx5Δ cells to the oxidants. Importantly, subjecting purified ribosomes to an in vitro iron/ascorbate reaction precisely recapitulated the 25S rRNA cleavage pattern observed in cells, indicating that redox activity of the ribosome-bound iron is responsible for the strand breaks in the rRNA. In summary, our findings provide evidence that oxidative stress-associated rRNA cleavages can occur through rRNA strand scission by redox-active, ribosome-bound iron that potentially promotes Fenton reaction-induced hydroxyl radical production, implicating intracellular iron as a key determinant of the effects of oxidative stress on ribosomes. We propose that iron binding to specific ribosome elements primes rRNA for cleavages that may play a role in redox-sensitive tuning of the ribosome function in stressed cells.

Comments

“Authors are allowed to do the following:…to post the final edited PDFs, created by ASBMB, to their own departmental/university websites, provided that the posting does not happen until 12 months after publication of the work, and that a link to the article on the journal site is included.”

This research was originally published in the Journal of Biological Chemistry. Zinskie JA, Ghosh A, Trainor BM, Shedlovskiy D, Pestov DG, Shcherbik N. Iron-dependent cleavage of ribosomal RNA during oxidative stress in the yeast Saccharomyces cerevisiae. J Biol Chem. 2018; 293:14237-14248. © the Author(s).

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