TrmB, a tRNA m7G46 methyltransferase, plays a role in hydrogen peroxide resistance and positively modulates the translation of katA and katB mRNAs in Pseudomonas aeruginosa.

Abstract

Cellular response to oxidative stress is a crucial mechanism that promotes the survival of Pseudomonas aeruginosa during infection. However, the translational regulation of oxidative stress response remains largely unknown. Here, we reveal a tRNA modification-mediated translational response to H2O2 in P. aeruginosa. We demonstrated that the P. aeruginosa trmB gene encodes a tRNA guanine (46)-N7-methyltransferase that catalyzes the formation of m7G46 in the tRNA variable loop. Twenty-three tRNA substrates of TrmB with a guanosine residue at position 46 were identified, including 11 novel tRNA substrates. We showed that loss of trmB had a strong negative effect on the translation of Phe- and Asp-enriched mRNAs. The trmB-mediated m7G modification modulated the expression of the catalase genes katA and katB, which are enriched with Phe/Asp codons at the translational level. In response to H2O2 exposure, the level of m7G modification increased, consistent with the increased translation efficiency of Phe- and Asp-enriched mRNAs. Inactivation of trmB led to decreased KatA and KatB protein abundance and decreased catalase activity, resulting in H2O2-sensitive phenotype. Taken together, our observations reveal a novel role of m7G46 tRNA modification in oxidative stress response through translational regulation of Phe- and Asp-enriched genes, such as katA and katB.