NUCLEOTIDE-SEQUENCE OF THE SALMONELLA-TYPHIMURIUM TRPR GENE

The sequence of the Salmonella typhimurium trpR gene and flanking DNA was determined on both strands. The DNA sequence predicts a polypeptid e product of 108 amino acids with a molecular weight of 12,274 daltons . The TrpR protein of S. typhimurium differs by three amino acid resid ues from that of E. coli. The promoter/operator region of trpR is comp letely conserved between E. coli and S. typhimurium. The nucleotide se quence of the trpR sector of the S. typhimurium genome was 87.4% ident ical to the corresponding region of the E. coli genome. Within the pro tein coding segments of the two organisms, 94.4% of the amino acid res idues were identical. In S. typhimurium, as in E. coli, there is a Pal indromic Unit element (PU) between the translation termination triplet of trpR and that of a divergently oriented unidentified reading frame (URF-143). However, the PU segment of S. typhimurium is 85 nucleotide s shorter than its E. coli counterpart.