Queuosine modification of tRNA-Tyr elicits translational reprogramming and enhances growth of Vibrio cholerae with aminoglycosides

Tgt is responsible for the queuosine (Q) modification of the guanine (G) in tRNAs with GUN anti-codon. We have previously identified tgt as being vital for growth in presence sub-lethal concentrations of aminoglycosides in Vibrio cholerae. Here we further explore the role of Q modification in translation fidelity and efficiency of codon decoding upon tobramycin exposure. We characterize the impact on codon decoding efficiency, the overall translation of the bacterial proteome, and the molecular mechanisms underlying the effects of Q modification in antibiotic stress response. Using molecular reporters, we show that Q modification impacts the efficiency of decoding at tyrosine TAT and TAC codons. Proteomics identify the anti-SoxR factor RsxA as 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 identify conditions which 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 identifies candidate genes possibly subjected to such translational regulation, among which DNA repair factors. Such transcripts, which fit the definition of modification tunable transcripts, are plausibly central in the bacterial response to antibiotic stress.