Locations of the opp and supX genes of Salmonella typhimurium and Escherichia coli.

The chromosomal locations of the supX and opp loci of Salmonella typhimurium LT2 and Escherichia coli K-12 were identified and found to result in the same gene sequence in both species, namely, pyrF-cysB-supX-trpPOLEDCBA-tonB(chr)-opp. These results differ from a previously reported location of the opp gene on the E. coli chromosome. Evidence indicates that the opp gene lies between chr(tonB) and galU in S. typhimurium.