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Accurate translation of the genetic code is maintained in part by aminoacyl-tRNA synthetases (aaRS) proofreading mechanisms that ensure correct attachment of a cognate amino acid to a transfer RNA (tRNA). During environmental stress, such as oxidative stress, demands on aaRS proofreading are altered by changes in the availability of cytoplasmic amino acids. For example, oxidative stress increases levels of cytotoxic tyrosine isomers, noncognate amino acids normally excluded from translation by the proofreading activity of phenylalanyl-tRNA synthetase (PheRS). Here we show that oxidation of PheRS induces a conformational change, generating a partially unstructured protein. This conformational change does not affect Phe or Tyr activation or the aminoacylation activity of PheRS. However, in vitro and ex vivo analyses reveal that proofreading activity to hydrolyze Tyr-tRNA Phe is increased during oxidative stress, while the cognate Phe-tRNA Phe aminoacylation activity is unchanged. In HPX − , Escherichia coli that lack reactive oxygen-scavenging enzymes and accumulate intracellular H 2 O 2 , we found that PheRS proofreading is increased by 11%, thereby providing potential protection against hazardous cytoplasmic m -Tyr accumulation. These findings show that in response to oxidative stress, PheRS proofreading is positively regulated without negative effects on the enzyme’s housekeeping activity in translation. Our findings also illustrate that while the loss of quality control and mistranslation may be beneficial under some conditions, increased proofreading provides a mechanism for the cell to appropriately respond to environmental changes during oxidative stress.
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Regulation of tRNA‐dependent translational quality control
Abstract Translation is the most error‐prone process in protein synthesis; however, it is important that accuracy is maintained because erroneous translation has been shown to affect all domains of life. Translational quality control is maintained by both proteins and RNA through intricate processes. The aminoacyl‐tRNA synthetases help maintain high levels of translational accuracy through the esterification of tRNA and proofreading mechanisms. tRNA is often recognized by an aminoacyl‐tRNA synthetase in a sequence and structurally dependent manner, sometimes involving modified nucleotides. Additionally, some proofreading mechanisms of aminoacyl‐tRNA synthetases require tRNA elements for hydrolysis of a noncognate aminoacyl‐tRNA. Finally, tRNA is also important for proper decoding of the mRNA message by codon and anticodon pairing. Here, recent developments regarding the importance of tRNA in maintenance of translational accuracy are reviewed. © 2019 IUBMB Life, 2019 © 2019 IUBMB Life, 71(8):1150–1157, 2019
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- Award ID(s):
- 1715840
- PAR ID:
- 10460656
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- IUBMB Life
- Volume:
- 71
- Issue:
- 8
- ISSN:
- 1521-6543
- Page Range / eLocation ID:
- p. 1150-1157
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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