FIGURE 2.

Mechanism of increased mRNA levels of ampC in IRP41. (A) Relative mRNA levels of ampC gene in indicated strains. Total RNA was isolated from indicated strains at OD₆₀₀ of 1.0, and the relative mRNA levels of ampC were determined by real-time qPCR using rpsL as an internal control. ns, not significant, ***P < 0.001, by Student’s t-test. (B) Levels of AmpC-His in indicated strains detected with Western blot assay. Strains with an ampC-His in their chromosomes were cultured to OD₆₀₀ of 1.0. Samples from equal number of bacterial cells were loaded onto 12% SDS-PAGE gels and probed with an antibody against His-tag or RpoA. The RNA polymerase alpha subunit RpoA served as a control.