SdsR affects expression of genes within the CRP regulon. (A) Wild-type and ΔsdsR Salmonella carrying either a control vector, or the constitutive SdsR-expression plasmid pPL-SdsR were grown in LB, and RNA isolated at different time-points over growth (OD600 of 0.5 (lanes 1, 5, 9); 1.0 (lanes 2, 6, 10); 2.0 (lanes 3, 7, 11); 3 h after cells had reached an OD600 of 2.0 (lanes 4, 8, 12)) was analyzed on Northern blots. The two sRNAs Spot42 and CyaR were probed with sequence-specific oligos. SdsR and crp mRNA were detected using riboprobes. 5S rRNA served as loading control. (B) Wild-type and ΔsdsR Salmonella carrying either a control vector, or the constitutive SdsR-expression plasmid pPL-SdsR were grown in M9 minimal medium supplemented with 0.4% glucose. At OD600 of 0.5, cells were harvested by centrifugation, washed in M9, and resuspended in M9 supplemented either with 0.4% glucose or 0.2% maltose, respectively, as sole carbon source. RNA was prepared from samples collected prior to, and at 15 and 30 min post carbon source shift. Spot42, CyaR, SdsR and 5S rRNA were detected as described in (A).