TABLE 1.

Transcriptional activities of the ltrRP2 and ltrRP1 wild-type promoters and mutated derivatives^a

Plasmid	Mean CAT sp act (μmol min−1 mg−1) for S. Typhi IMSS-1 ± SD
pKK8/ltrR-144+90	1,529 ± 101
pKK8/ltrR-144+90ΔP2	1,007 ± 6
pKK8/ltrR-144+90ΔP1	659 ± 2
pKK8/ltrRP2-471-1	521 ± 32
pKK8/ltrRP1+7+90	1,109 ± 60
pKK232-8	0 ± 0

^aThe fusions were named according to the ltrR translational initiation site; the numbers in each fusion represent the distances upstream and downstream of the ATG start site, with the fusions pKK8/ltrR-144+90ΔP1 and pKK8/ltrR-144+90ΔP2 containing individual substitutions in the −10 box. pKK232-8 was introduced into the S. Typhi wild-type strain to determine basal activity. The right column represents the expression levels of the ltrR fusions evaluated in the wild-type S. Typhi IMSS-1 strain. The activities were determined at an OD₅₉₅ of 0.6 in N-MM. The values are the means ± standard deviations from at least three independent experiments performed in duplicate (n ≥ 6).