Characterization of RNA damage under oxidative stress in Escherichia coli

Abstract

We have examined the level of 8-hydroxyguanosine (8-oxo-G), an oxidized form of guanosine, in RNA in Escherichia coli under normal and oxidative stress conditions. The level of 8-oxo-G in RNA rises rapidly and remains high for hours in response to hydrogen peroxide (H2O2) challenge in a dose-dependent manner. H2O2 induced elevation of 8-oxo-G content is much higher in RNA than that of 8-hydroxydeoxyguanosine (8-oxo-dG) in DNA. Under normal conditions, the 8-oxo-G level is low in RNA isolated from the ribosome and it is nearly three times higher in non-ribosomal RNAs. In contrast, 8-oxo-G generated by a short exposure to H2O2 is almost equally distributed in various RNA species, suggesting that although ribosomal RNAs are normally less oxidized, they are not protected against exogenous H2O2. Interestingly, highly folded RNA is not protected from oxidation because 8-oxo-G generated by H2O2 treatment in vitro increases to approximately the same levels in tRNA and rRNA in both native and denatured forms. Lastly, increased RNA oxidation is closely associated with cell death by oxidative stress. Our data suggests that RNA is a primary target for reactive oxygen species and RNA oxidation is part of the paradox that cells have to deal with under oxidative stress.

Bactericidal Antibiotics Induce Toxic Metabolic Perturbations that Lead to Cellular Damage

“…We found that the basal levels of 8-oxo-G on the RNA pool were about three times higher than the levels of 8-oxo-dG on DNA (Figure 5B). In addition, the RNA pool showed increased 8-oxo-G content in all treatment conditions ranging from a 113% increase with Kan to a 175% increase with Amp; the H 2 O 2 positive control (Liu et al, 2012) had the largest increase at 478%.…”

<b><i>Salmonella</i></b> and Reactive Oxygen Species: A Love-Hate Relationship

“…First, nucleic acids act as a target for ROS-induced damage causing strand breaks, mutagenesis, and modification of nucleotide bases [3, 78, 79]. Indeed, components of the DNA repair machinery, such as recA , lexA , and sulA appear to be of high importance for virulence and ROS tolerance in S .…”

“…Indeed, components of the DNA repair machinery, such as recA , lexA , and sulA appear to be of high importance for virulence and ROS tolerance in S . Typhimurium [79-82]. In S .…”

Quality control of chemically damaged RNA

“…Ribosomal RNA (rRNA) is generally thought to be a poor target, given its complexity of folding and association with ribosomal proteins; however, under oxidative stress conditions, this may not be the case. In contrast to measurements under normal conditions, where 8-oxoG from rRNA is lower compared with that of total RNA, after treatment with H 2 O 2, rRNA oxidation in E. coli correlated with the amount of 8-oxoG in the cell [62, 63]. The effects of oxidative stress on rRNA have also been observed in regions of the brain affected by AD.…”