Figure 4.

Gel mobility shift assays of purified CsrA binding to sRNAs. (A) Samples containing 5′ end-labeled wild-type or mutant McaS RNA (0.25 nM) were incubated with increasing amounts of CsrA protein (at the indicated concentrations). (B) Gel mobility shift assays of CsrA binding to GcvB and RprA RNA carried out as in A. (C) CsrB competition with McaS for binding to CsrA. Samples containing a fixed concentration of labeled McaS RNA (1 nM) and either 5 nM or 50 nM CsrA protein were incubated with the indicated concentrations of unlabeled CsrB RNA.