FIG 6.

Effect of SigB on rbsR. (A) Northern blot analysis. Total RNAs were prepared from 4-h cultures (OD₆₀₀, ∼4.0) of S. aureus CYL11481 or the sigB1(Am) mutant (CYL13113; contains an amber mutation in sigB) and hybridized with an rbsR-specific probe. (B) E. coli bacterial two-plasmid system. A promoter region of rbsR, PrbsR1 (153 bp) or PrbsR2 (756 bp), was cloned into the promoter probe plasmid pSB40N (giving pML4261 or pML4262, respectively) and transformed into E. coli XL1-Blue containing pAC7-sigB or pAC7. Clones were selected on LBACX-ARA plates. Positive transformants (containing pAC7-sigB) were blue, whereas negative controls (containing the pAC7 vector) were colorless. The longer PrbsR2 region was used in the study to include potential unknown upstream promoters.