# Interplay between mistranslation and oxidative stress in Escherichia coli

## TL;DR

The paper shows that mistranslation in E. coli can slightly help bacterial growth under oxidative stress, but only under specific conditions.

## Contribution

The study reveals a modest adaptive effect of isoleucine mistranslation in oxidative stress under specific growth conditions.

## Key findings

- Mistranslation with valine or norvaline did not benefit E. coli under oxidative stress when pre-incubated.
- Mistranslation slightly improved growth when E. coli was grown in valine-supplemented medium before oxidative stress.
- The study highlights a delicate balance between harmful and beneficial effects of mistranslation.

## Abstract

Mistakes in translation are mostly associated with toxic effects in the cell due to the production of functionally aberrant and misfolded proteins. However, under certain circumstances mistranslation can have beneficial effects and enable cells to preadapt to other stress conditions. Mistranslation may be caused by mistakes made by aminoacyl-tRNA synthetases, essential enzymes that link amino acids to cognate tRNAs. There is an Escherichia coli strain expressing isoleucyl-tRNA synthetase mutant variant with inactivated editing domain which produces mistranslated proteomes where valine (Val) and norvaline (Nva) are misincorporated into proteins instead of isoleucine. We compared this strain with the wild-type to determine the effects of such mistranslation on bacterial growth in oxidative stress conditions. When the cells were pre-incubated with 0.75 mmol/L Nva or 1.5 mmol/L Val or Nva and exposed to hydrogen peroxide, no beneficial effect of mistranslation was observed. However, when the editing-deficient strain was cultivated in medium supplemented with 0.75 mmol/L Val up to the early or mid-exponential phase of growth and then exposed to oxidative stress, it slightly outgrew the wild-type grown in the same conditions. Our results therefore show a modest adaptive effect of isoleucine mistranslation on bacterial growth in oxidative stress, but only in specific conditions. This points to a delicate balance between deleterious and beneficial effects of mistranslation.