Innate immune and chemically triggered oxidative stress modifies translational fidelity


Translational fidelity, essential for protein and cell function, requires accurate transfer RNA (tRNA) aminoacylation. Purified aminoacyl-tRNA synthetases exhibit a fidelity of one error per 10,000 to 100,000 couplings1,2. The accuracy of tRNA aminoacylation in vivo is uncertain, however, and might be considerably lower3,4,5,6. Here we show that in mammalian cells, approximately 1% of methionine (Met) residues used in protein synthesis are aminoacylated to non-methionyl-tRNAs. Remarkably, Met-misacylation increases up to tenfold upon exposing cells to live or non-infectious viruses, toll-like receptor ligands or chemically induced oxidative stress. Met is misacylated to specific non-methionyl-tRNA families, and these Met-misacylated tRNAs are used in translation. Met-misacylation is blocked by an inhibitor of cellular oxidases, implicating reactive oxygen species (ROS) as the misacylation trigger. Among six amino acids tested, tRNA misacylation occurs exclusively with Met. As Met residues are known to protect proteins against ROS-mediated damage7, we propose that Met-misacylation functions adaptively to increase Met incorporation into proteins to protect cells against oxidative stress. In demonstrating an unexpected conditional aspect of decoding mRNA, our findings illustrate the importance of considering alternative iterations of the genetic code.

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Figure 1: Induction of tRNA misacylation by viruses.
Figure 2: Misacylated tRNAs are used in translation.
Figure 3: tRNA misacylation induced by TLR ligands.
Figure 4: Oxidative stress induces NADPH-oxidase-dependent RNA misacylation.

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The microarray platforms are deposited in the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) database under accession numbers GPL9427 and GPL9428.


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The authors are grateful to D. Klinman for his gift of CpG oligonucleotides and advice, A. Schilling for supervision and advice on mass spectrometry experiments, and C. Nicchitta, T. Pierson, P. Cluzel, R. Levine, A. Iwasaki and S. Amigorena for insight and advice. This work was supported by the Division of Intramural Research, the National Institute of Allergy and Infectious Diseases, and by National Institutes of Health extramural pilot projects.

Author Contributions N.N., J.M.G., A.D., K.A.D., R.B.J., J.R.S., D.B., E.M.E, M.R.R., J.S.B., A.E., B.D., S.D., H.D.H., P.B. and T.P. designed and performed experiments, and analysed data. J.S.G. generated genetic constructs. J.R.B. and J.W.Y designed experiments and analysed data. J.W.Y. and T.P. conceived the project and wrote the paper. J.W.Y. and T.P. contributed equally to this paper.

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Correspondence to Jonathan W. Yewdell or Tao Pan.

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Netzer, N., Goodenbour, J., David, A. et al. Innate immune and chemically triggered oxidative stress modifies translational fidelity. Nature 462, 522–526 (2009).

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