Figure 2. Substitutions in the stem-loop and U-stretch of the trp attenuator.

(A) Diagram depicting the WT and mutant trp attenuators with altered bases in the stem-loop structure or U-stretch. Substitutions are indicated in bold and are underlined. Numbers adjacent to structure names indicate fold TRAP regulation observed in vivo using β-galactosidase assays (results in Table 1). (B) Schematic representation of the transcriptional reporter fusions with lacZ that were used to examine TRAP-mediated regulation of transcription termination in vivo. The arrow represents the trp promoter and trpL refers to the regulatory leader region (See Methods for details about each gene fusion). Each trpE′-′lacZ fusion was integrated into the B. subtilis genome at the amyE locus.