The control region of the metH gene of Salmonella typhimurium LT2: an atypical met promoter.

The control region of the Salmonella typhimurium metH gene was sequenced and the transcription start point was determined by S1 nuclease mapping experiments. Activation of the metH gene by the metR gene product was shown to occur at the level of transcription. The translation start site was determined by amino acid sequence analysis of the amino terminus of a chimeric Met-Lac fusion protein encoded by a metH-lacZ gene fusion. Analysis of the nucleotide sequence of the metH promoter region showed that two sequence elements, present in the promoters of all other met biosynthetic genes thus far examined, are not present in the metH promoter region, namely, the repeated MetJ repressor recognition sequence 5'-AGACGTCT-3' and a highly conserved sequence 5'-TGGA----TAAAC-3' of unknown function.