Balanced Input from the tRNA Prenyltransferase MiaA Controls the Stress Resistance and Virulence Potential of Extraintestinal Pathogenic Escherichia coli

In Escherichia coli, the highly conserved enzymes MiaA and MiaB mediate the sequential prenylation and methylthiolation of adenosine-37 within tRNAs that decode UNN codons. We found that MiaA, but not MiaB, is critical to the fitness and virulence of extraintestinal pathogenic E. coli (ExPEC), a major cause of urinary tract and bloodstream infections. Deletion of miaA has pleiotropic effects, attenuating bacterial fitness and virulence within diverse host environments and rendering ExPEC especially sensitive to stressors like nitrogen and oxygen radicals and osmotic shock. We find that stress can stimulate striking changes in miaA expression. To assess how changing MiaA levels affect the pathogen proteome, we used MS to analyze the proteins express by the reference ExPEC isolate UTI89 and derivatives that either lack or overexpress MiaA.