FIG. 3.

(A) Activity of the ompS2 gene depends on the length of the regulatory region and on the ompB operon. β-Galactosidase-specific activities rendered by pFM fusion plasmids, containing various lengths of the 5′ regulatory region as indicated by their numeral denomination (Fig. 2), harbored in S. enterica serovar Typhi are shown. The gray bars depict activities in the wild-type (WT) strain; black bars show activity in the isogenic S. enterica serovar Typhi 81 (ΔompB::Km) strain. (B) Mapping by primer extension of the first (+1) transcribed G residue of the ompS2 gene. The initiation of transcription is shown from pFM413, in the absence (−) and in the presence (+) of the leuO gene (cloned in ptrcleuO); from pFM97, lacking 317 bp between −413 and −97; and from pFM34. The Shine-Dalgarno (SD) sequence, the first methionine of the ORF, and the GATC sequence ladder of the complementary strand are shown.