Beyond RNA modification: a novel role for tRNA modifying enzyme in oxidative stress response and metabolism.

RNA modifications play a fundamental role in regulating essential cellular processes, including translation fidelity and stress adaptation. While these modifications are installed post-transcriptionally by specialized enzymes, their broader functional roles remain largely unexplored. Here, we uncover an unexpected function for the Vibrio cholerae tRNA dihydrouridine synthase B (VcDusB) beyond its canonical role in tRNA dihydrouridylation. We show that deletion of dusB severely compromises V. cholerae resistance to oxidative stress, not through the loss of tRNA modification, but via disruption of an intrinsic NADPH oxidase activity. Mutational analyses reveal that DusB redox function is essential for survival under oxidative stress. Proteomic and transposon insertion sequencing analysis further linked DusB to NADPH homeostasis and metabolic reprogramming during stress adaptation. These findings redefine DusB as a bifunctional enzyme coupling tRNA modification to redox regulation, expanding the functional repertoire of RNA-modifying enzymes in stress adaptation. More broadly, this work paves the way for exploring the evolutionary versatility of tRNA-modifying enzymes, suggesting that their functions extend far beyond RNA metabolism to direct integration of translational control with cellular redox state.