Aminoglycoside tolerance inVibrio choleraeengages translational reprogramming associated to queuosine tRNA modification

Abstract

Tgt is the enzyme modifying the guanine (G) in tRNAs with GUN anti-codon to queuosine (Q). tgt is required for optimal growth of Vibrio cholerae in the presence of sub-lethal aminoglycoside concentrations. We further explored here the role of the Q in the efficiency of codon decoding upon tobramycin exposure. We characterized its impact on the overall bacterial proteome, and elucidated the molecular mechanisms underlying the effects of Q modification in antibiotic translational stress response. Using molecular reporters, we showed that Q impacts the efficiency of decoding at tyrosine TAT and TAC codons. Proteomics analyses revealed that the anti-SoxR factor RsxA is better translated in the absence of tgt. RsxA displays a codon bias towards tyrosine TAT and its overabundance leads to decreased expression of genes belonging to SoxR oxidative stress regulon. We also identified conditions that regulate tgt expression. We propose that regulation of Q modification in response to environmental cues leads to translational reprogramming of genes bearing a biased tyrosine codon usage. In silico analysis further identified candidate genes possibly subject to such translational regulation, among which DNA repair factors. Such transcripts, fitting the definition of modification tunable transcripts, are plausibly central in the bacterial response to antibiotics.

Escherichia coli Aggregates Mediated by Native or Synthetic Adhesins Exhibit Both Core and Adhesin-Specific Transcriptional Responses

“…Decreased expression of these different translational modifiers might increase the rate of mistranslation and, thus, enhance tolerance toward several antibiotics ( 30 ). Notably, some recent works have shown that specific tRNA modifications could be directly involved in enhanced tolerance of aminoglycosides ( 31 , 32 ).…”

Beyond the Anticodon: tRNA Core Modifications and Their Impact on Structure, Translation and Stress Adaptation

“…Most importantly, this study showed that the effect on fitness in the presence of sub-MIC antibiotics in tRNA modification deletion strains also impacts tolerance to lethal doses of the antibiotics. Although the molecular mechanisms underlying the effects of the queuosine Q34 modification in the antibiotic translational stress response have subsequently been described in detail [ 169 ], the mechanisms by which tRNA core modification affects antibiotic tolerance are still elusive, and their study may certainly shed new light on the subtle functions of this group of modifications.…”

Escherichia coliaggregates mediated by native or synthetic adhesins exhibit both core and adhesin-specific transcriptional responses

“…Decreased expression of these different translational modifiers might be increasing the rate of mistranslation and thus enhanced tolerance towards several antibiotics (Witzky et al, 2019). Notably some recent works have shown that specific tRNA modification could be directly involved in enhanced tolerance to aminoglycosides (Babosan et al, 2022;Fruchard et al, 2022).…”