RNA damage and degradation under oxidative stress

Abstract

RNA is extensively damaged under oxidative stress (OS) and becomes dysfunctional. Oxidized RNAs are presumably degraded by selective surveillance mechanisms which control the quality of cellular RNA. We have identified many proteins in Escherichia coli that bind oxidized RNA at high affinity. In this work, we have studied the role of 138 proteins, including the ones binding oxidized RNA and others function in RNA metabolism, in supporting cell viability under OS. Nearly 40 proteins showed protective effect against H2O2 treatment, including RNases, RNA helicases, poly(A) polymerase, and enzymes involved in RNA modification. Mutants lacking an RNase and another enzyme in combination are frequently more sensitive to H2O2. Under OS, cells defective in RNA degradation contain elevated 8‐hydroxyguanosine, an oxidized RNA lesion, as determined by HPLC. Ribosomal RNAs account for 80% of total RNA and are normally stable, presumably carrying the majority of oxidized nucleotides. RNA profile analysis using Agilent Bioanalyzer revealed increased fragmentation of rRNA in some of the strains upon H2O2 treatment. These data suggest that a number of proteins function in removing damaged rRNA. The specific roles of individual activities in targeting, fragmenting and degrading oxidized RNA are studied in details. This project is supported by FAU Integrative Biology Ph.D. Program to M.L. and NIH grant S06 GM073621 to Z.L.