Figure 1.

MiaA promotes ExPEC fitness and virulence within diverse host niches. (A) MiaA and MiaB act sequentially to modify tRNA molecules that recognize UNN codons; modified from (28). HDMAPP, mono[(2E)-hydroxy-3-methyl-2-butenyl] ester diphosphoric acid; DMAPP, dimethylallyl diphosphate; SAM, S-adenosylmethionine; SAH, S-adenosylhomocysteine; Cys, cysteine. (B and C) To assess gut colonization, adult BALB/c mice were inoculated via oral gavage with ∼10⁹ CFU of a 1:1 mixture of (B) UTI89 and UTI89ΔmiaA or (C) UTI89 and UTI89ΔmiaB. Fecal titers were determined at the indicated time points and used to calculate competitive indices (CI). ***P< 0.001; ****P < 0.0001 by one sample t-tests. n = 7–8 mice from two independent experiments. (D) The bladders of adult female CBA/J mice were inoculated via transurethral catheterization with ∼10⁷ CFU of UTI89, UTI89ΔmiaA, or UTI89ΔmiaB. Mice were sacrificed 3 days later and bacterial titers within the bladders were determined by plating tissue homogenates. **P < 0.01 by Mann–Whitney U tests; n≥ 19 mice per group from at least three independent experiments. In (B), (C) and (D), bars indicate median values; dots represent individual mice. (E) Kaplan–Meier survival curves of C57Bl/6 mice inoculated via i.p. injections with ∼10⁷ CFU of UTI89 (black line), UTI89ΔmiaA (blue) or UTI89ΔmiaB (orange). ****P < 0.0001 by log-rank Mantel Cox test for UTI89 versus UTI89ΔmiaA; n= 13 mice per group from two independent experiments.