Figure 1.
Repression of rpoS expression by CyaR. (A) Schematic presenting the rpoS-lacZ translational fusion. PBAD, the arabinose-inducible pBAD promoter; +1, the rpoS transcription start site; ATG, the rpoS translation start codon. The sequence encoding the 5ʹ-upstream 606 nt of the rpoS mRNA was fused in frame to lacZ. (B-D) Repression of rpoS by overexpression of CyaR in PM1409 (WT) cells carrying the rpoS-lacZ translational fusion. (B) LacZ activity, (C) rpoS mRNA level, and (D) rpoS-lacZ mRNA level were measured. mRNA levels were analysed by qRT-PCR and were normalized to rrsA expression. (E-G) rpoS activation in the absence of CyaR. (E) LacZ activity, (F) rpoS-lacZ mRNA level, and (G) rpoS mRNA level for WT and ΔcyaR cells were measured. The ratios of LacZ activity, and rpoS-lacZ and rpoS mRNA levels to those of WT are shown. Values are means ± SD; n = 3; **P < 0.01, *P < 0.05; ns, not significant (Student’s t-test, equal variance with the control vector across expression values). pCyaR, a plasmid overexpressing CyaR; V, vector control; ΔcyaR, PM1409ΔcyaR.