Transfer RNAs Mediate the Rapid Adaptation of Escherichia coli to Oxidative Stress

Abstract

Translational systems can respond promptly to sudden environmental changes to provide rapid adaptations to environmental stress. Unlike the well-studied translational responses to oxidative stress in eukaryotic systems, little is known regarding how prokaryotes respond rapidly to oxidative stress in terms of translation. In this study, we measured protein synthesis from the entire Escherichia coli proteome and found that protein synthesis was severely slowed down under oxidative stress. With unchanged translation initiation, this slowdown was caused by decreased translation elongation speed. We further confirmed by tRNA sequencing and qRT-PCR that this deceleration was caused by a global, enzymatic downregulation of almost all tRNA species shortly after exposure to oxidative agents. Elevation in tRNA levels accelerated translation and protected E. coli against oxidative stress caused by hydrogen peroxide and the antibiotic ciprofloxacin. Our results showed that the global regulation of tRNAs mediates the rapid adjustment of the E. coli translation system for prompt adaptation to oxidative stress.

VapCs of Mycobacterium tuberculosis cleave RNAs essential for translation

“…However, it is possible that cleavage of RNAs essential for translation similarly confers protection by inhibiting cell growth, as proposed previously by other groups (8,16,17,33). Consistent with this proposal, E. coli rapidly responds to oxidative stress by downregulating translation via tRNA degradation (34). It is also possible that the vapBC genes can prevent bacteriophages from spreading in cell populations by inducing so-called ‘abortive infection’ that has been described for type III TA modules also encoding inhibitors of translation (35,36).…”

Phosphorylation of Eukaryotic Initiation Factor-2α during Stress and Encystation in Entamoeba Species

“…histolytica [25]. It has been suggested that oxidation of components of the parasite’s translation machinery (e.g., ribosomal proteins, elongation factors) [25], and enzymatic down-regulation of almost all tRNA species [31] are responsible for reduced protein biosynthesis during H 2 O 2 exposure. Our data show that phosphorylation of eIF2α may also contribute to changes in gene expression and protein biosynthesis during oxidative stress in the pathogen.…”

Transfer RNA instability as a stress response inEscherichia coli: Rapid dynamics of the tRNA pool as a function of demand

“…This finding, together with the finding that the kinetics of tRNA decay upon amino acid starvation are similar in wild-type E. coli and a relA mutant, suggests that tRNA instability is not a unique consequence of the stringent response, but may occur as a general response to stresses that reduce translation. 14 The argument is supported by a recent report of extensive tRNA degradation during oxidative stress, 30 which causes stalling of ribosomes at 8-oxoG residues in the mRNA 31 and thereby also limits the pool of functionally intact mRNA available for translation. Since the capacity to synthesize new protein is severely reduced during amino acid starvation, a tRNA-degradation mechanism that depends on synthesis of new protein may not be feasible.…”

“…The recent studies mentioned above 14,30 suggest that tRNA degradation could play an important, but hitherto overlooked, role in the bacterial stress response to amino acid starvation as well as other stresses that affect the availability of substrates for translation. Many questions about the process and the importance of tRNA degradation during stress conditions remain to be answered.…”