FIG. 4.

RNase T2 protection assays of transcripts from the pdxH-tyrS-pdxY-gst region of the E. coli K-12 chromosome. Total RNA was purified from strain NU426 growing exponentially in LB medium at 37°C, and RNase T2 protection assays were performed as described in Materials and Methods. The positions of RNA probes 1 to 5 used for this assay are indicated in Fig. 2. Probes 1 to 5 correspond to the pdxH, tyrS, and pdxY noncoding strands and hybridized with pdxH, tyrS, and pdxY transcripts. Probes 4o and 5o are complementary to probes 4 and 5, respectively, and hybridized to gst transcripts. See the text for additional details. a, unhybridized RNA probes; b, RNA probes hybridized with 50 μg of tRNA (self-hybridization control); c, RNA probes hybridized with 50 μg of total cellular RNA; s, RNA size standards (see Materials and Methods) (37); arrowheads, protected RNA species described in Results and Discussion.