An Active Role for the Ribosome in Determining the Fate of Oxidized mRNA

Chemical damage to RNA affects its functional properties and thus may pose a significant hurdle to the translational apparatus; however, the effects of damaged mRNA on the speed and accuracy of the decoding process and their interplay with quality-control processes are not known. Here, we systematically explore the effects of oxidative damage on the decoding process using a well-defined bacterial in vitro translation system. We find that the oxidative lesion 8-oxoguanosine (8-oxoG) reduces the rate of peptide-bond formation by more than three orders of magnitude independent of its position within the codon. Interestingly, 8-oxoG had little effect on the fidelity of the selection process, suggesting that the modification stalls the translational machinery. Consistent with these findings, 8-oxoG mRNAs were observed to accumulate and associate with polyribosomes in yeast strains in which no-go decay is compromised. Our data provide compelling evidence that mRNA-surveillance mechanisms have evolved to cope with damaged mRNA. [Display omitted] •Oxidized mRNA is detrimental for tRNA selection on the ribosome•8-oxoG stalls translation regardless of its position within the codon•In the absence of no-go decay factors, 8-oxoG-containing mRNAs accumulate in vivo•mRNA surveillance mechanisms have evolved to deal with damaged mRNA Oxidative damage to RNA has received relatively little attention despite evidence that it can accumulate in cells and is associated with numerous disease states. Simms et al. demonstrate that a single modified residue in an mRNA can lead to ribosomal stalling. Cells in which no-go decay is compromised show increased levels of 8-oxoG mRNA, suggesting that mRNA surveillance mechanisms may have evolved to cope with damaged mRNA.