TABLE 1.

tRNA modifications screened for an effect on RpoS expression

Genotypea	Biochemical activity removed by mutation	Lac
Wild type	None	+
ΔtruA	tRNA pseudouridine synthase, anticodon stem-loop specific	+
ΔtruB	tRNA pseudouridine synthase, Ψ55 specific	+
ΔrluA	Pseudouridine synthase, 23S rRNA and tRNAphe specific	+
ΔrluC	Pseudouridine synthase, 23S rRNA, positions 955, 2504, and 2580	+
ΔrsuA	Pseudouridine synthase, 16S rRNA position 516	+
ΔmiaA	UXX codon tRNA prenyl transferase at position 37	–
ΔmiaB	UXX codon tRNA methylthiolase following prenylation	+

^aThe mutations were transduced into the wild-type rpoS750-lacZ translational fusion strain (EM1050) and tested for expression phenotypes on MacConkey-lactose plates incubated overnight at 37°C. Strain names are given in Table S1 in the supplemental material.