FIG. 4.
Effect of σB on arlRS expression. (A) Schematic representation of the arlRS region of S. aureus COL. ORFs, promoters, terminators, and the regions used as probes are indicated. ORF notations and nucleotide (nt) numbers correspond to those of the respective genomic regions of strain COL (RefSeq accession no. NC_002951). (B) Northern blot analyses of the arlR and arlS transcriptions in strains GP268, COL, and Newman and their isogenic ΔrsbUVW-sigB mutants after 8 h of growth in LB at 37°C. Relevant transcript sizes and the probes used are indicated. Ethidium bromide-stained 16S rRNA patterns are shown as an indication of RNA loading.