FIG. 3.

Amounts of pdxA-ksgA cotranscript and ksgA- and pdxB-specific transcripts in exponentially growing E. coli K-12. (A) Autoradiograph of RNase T₂ protection assays. Equal amounts (50 μg) of RNA prepared from cultures of prototrophic strain NU426 grown in MMGly (lane 2), minimal salts-glucose medium (lane 3), enriched minimal salts-glycerol medium (lane 4), EMMG (lane 5), and LB (lane 6) were probed as described in Materials and Methods. Positions of bands corresponding to the pdxA-ksgA cotranscript (labeled pdxA) and the ksgA- and pdxB-specific transcripts are indicated. Lanes 1 and 7 show the undigested pdxA-ksgA and pdxB probes, respectively. The results were from at least three independent cultures at each growth rate. (B) Counts per minute corresponding to the pdxA-ksgA cotranscript (filled triangles), the ksgA-specific transcript (open rectangles), and the pdxB-specific transcript (open circles) were determined from gels such as the one in panel A by direct counting and plotted as a function of the growth rate.