FIG. 2.

GadX-dependent activation of gad genes. (A) Northern hybridization analysis of gad mRNAs extracted from E. coli JM109 carrying the pQE60 vector and the expression construct pQEgadX. Cells were grown at 37°C in neutral LB medium to the mid-exponential phase (OD₆₀₀ ≈ 0.8). Aliquots of 10 μg of total RNA were electrophoresed, transferred onto nylon filters, and hybridized with the gadA/B probe. Sizes of RNA standards are given on the right. (B) Immunoblot analysis of GadA and GadB expression in whole bacterial lysates (2.5 μg of protein) probed with anti-GadA/B polyclonal antibodies. The decarboxylase activity (Gad, in units per milligram) in the cell lysates and the GABA levels (millimolar) in the growth medium are given for each condition.