Aminoglycoside tolerance inVibrio choleraeengages translational reprogramming associated to queuosine tRNA modification

Tgt is the enzyme modifying the guanine (G) in tRNAs with GUN anticodon to queuosine (Q).tgtis required for optimal growth ofVibrio choleraein 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 oftgt. RsxA displays a codon bias towards tyrosine TAT and overabundance of RsxA leads to decreased expression of genes belonging to SoxR oxidative stress regulon. We also identified conditions that regulatetgtexpression. 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 silicoanalysis 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.