FIGURE 3.

CstR regulates the expression of immediately adjacent genes. A, schematic to scale representation of the genome encompassing locus tags NWMN_0026 to NWMN_0029 in S. aureus strain Newman in the immediate vicinity of NWMN_0026.5. Trivial names and the the number of amino acid residues of each encoded protein are shown, and the number of nucleotides that separate each ORF, for reference. TauE, putative sulfite/sulfonate effluxer; CstA and CstB, CsoR-like sulfur transferase-regulated genes A and B; SQR, putative sulfide:quinone reductase. SauSQR exhibits 57% identity to bona fide SQR from Bacillus stereothermophilus (Bst) (heavy metal tolerance-2 protein, HMT-2), which has been shown to catalyze sulfide-dependent menaquinone reduction (53). B, NWMN_0027 through NWMN_0029 form an operon. cDNA from ΔcstR was subjected to PCR using primers that anneal with the sqr and cstA genes and amplify a 2.7-kb product. No cDNA (RT) was used as a negative control, whereas chromosomal (Chrm) was used as a positive control. C–F, analysis of gene expression by quantitative RT-PCR. C, NWMN_0027 through 0029 and tauE levels in ΔcstR relative to wild type. NWMN_0027 and tauE levels in ΔcsoR (D) and wild-type (E) and in the presence and absence of copper. F, expression of copA in wild-type and ΔcstR strains. Results represent the average of three or more independent experiments. *, p < 0.05 determined by Student's t test. N.S., not significant. Error bars = S.D.