Fig. 1. McaS expression is induced during entry into stationary phase and by non-preferred carbon sources.

A. Genomic context of McaS. The gene encoding McaS (shaded grey) is located downstream of abgR, encoding a transcription regulator and upstream of ydaL, encoding a small MutS-related protein.

B. Sequence of McaS. The sequence of the sRNA is shaded grey. The RNA terminates within the poly(T) stretch of the rho-independent terminator (underlined sequence). The −10 and −35 promoter elements are indicated along with a putative CRP binding site. The abgR stop codon is also indicated.

C. Levels of the McaS, CyaR and Spot 42 RNAs and σ^S throughout growth. McaS, CyaR and Spot 42 levels were assayed by northern analysis of RNA taken from wild type MG1655 grown in LB media at 37°C for 30 h. At the indicated times (corresponding to OD₆₀₀ of ~0.1, 0.2, 0.6, 0.9, 1.8, 2.5, 4.7, 5.5, 6, and 6), total RNA was extracted and 10 μg was separated on an 8% polyacrylamide-7M urea gel, transferred to a membrane and probed with a ³²P-labeled oligonucleotide specific for McaS, CyaR, Spot 42 or 5S as a control. σ^S levels were assayed by western blot analysis of cells simultaneously.

D. Levels of McaS, CyaR and Spot 42 under conditions of carbon limitation. Wild type cells were grown in M63 minimal media with 0.2% glucose or 0.4% glycerol at 37°C for 30 h (O/N). RNA was extracted at the indicated OD₆₀₀ and northern analysis was performed as in C. Upon longer exposure, some McaS expression is observed for cells grown in minimal media with glucose.