FIG 2.
PBP1a and LpoA play important roles in cell growth and blaA expression. (A) PBP1a pathway mutants have impaired cell growth. The generation times for different strains were calculated from the OD600 values. ΔmrcAc and ΔlpoAc represent the ΔmrcA and ΔlpoA strains, respectively, complemented with pHG101 in trans. Results are averages for at least three replicates, and the error bars represent standard deviations (SD) (* and **, P < 0.05 and 0.01, respectively; two-tailed t test). (B) Enhanced β-lactam resistance in mrcA and lpoA mutants is dependent on blaA expression. PblaA promoter activities were determined by measuring β-galactosidase activity (in Miller units) by use of the PblaA-lacZ reporter system in different strains in the absence and presence of AMP at 50 μg/ml and 2.5 μg/ml. Results are averages for at least three replicates, and the error bars represent SD.