FIG 1.
Expression of rtxA in V. vulnificus with different genetic background and sequence analysis of the PrtxA regulatory region. (A) Total RNAs were isolated from the wild type (WT) and isogenic mutants grown to an A600 of 0.5 and used to determine the rtxA transcript levels. The rtxA transcript levels were determined by qRT-PCR analyses, and the rtxA transcript level in the wild type was set at 1. Error bars represent the standard deviations (SD). Statistical significance was determined by the multiple comparisons after one-way analysis of variance (ANOVA) (***, P < 0.0005; ns, not significant relative to the wild type). lrp, lrp mutant; crp, crp mutant; toxR, toxR mutant; iscR, iscR mutant; aphA, aphA mutant; aphB, aphB mutant; rpoS, rpoS mutant; smcR, smcR mutant. (B) The DNA sequence between rtxBDE and rtxHCA is shown. The transcription start site of the rtxHCA operon is indicated in boldface type and by a solid bent arrow, and the positions of the putative −10 and −35 regions are underlined. The putative translational initiation codons of rtxB and rtxH are indicated in boldface type and by the dashed bent arrow, respectively. The sequences for the binding of Lrp (LRPB1, LRPB2, and LRPB3; white boxes) and CRP (CRPB1, CRPB2, and CRPB3; gray boxes) were determined in this study. The sequences for the binding of HlyU (HLYUB) and H-NS (HNSB1, HNSB2, HNSB3, HNSB4, and HNSB5) are indicated by black box and hatched boxes, respectively.