FIG. 1.
Organization and transcription of the ilv-leu operon and deletion analysis of its promoter region. The gene organization of the ilv-leu region has been determined previously (9, 11). The ilv-leu operon, consisting of seven genes (ilvBHC and leuABCD), was transcribed from 482 bp upstream of the coding region for ilvB as a 8.5-kb mRNA; Pilv-leu is the promoter of ilv-leu. The ilv-leu terminator, designated Ter, is located in the leader region upstream of ilvB, and its presence resulted in a 0.4-kb transcript. The locations of the TnrA box and the introduced base substitutions (A to C and C to T) are indicated. The ysnD gene divergent with respect to ilv-leu was transcribed from the ysnD promoter (PysnD); the transcription initiation base corresponds to base −222 (base 1 is the transcription initiation base for ilv-leu). For deletion analysis of the promoter region, promoter regions at bases −248 to 26, −187 to 26, and −667 to 26 were fused with lacZ and then integrated into the amyE locus of B. subtilis, resulting in strains FU676, FU709, and FU710, respectively. The position of the DNA probe used for Northern analysis (l-ilvB) is also indicated.