Overlapping genes in the heat-labile enterotoxin operon originating from Escherichia coli human strain.

We have determined the nucleotide sequence at the distal end of the heat-labile enterotoxin subunit A (LT-A) gene (toxA) originating from human enterotoxigenic Escherichia coli. The sequenced region covers the entire LT-A2 region and a part of the LT-A1 region. In confirming our previous prediction based on product analysis of clones toxA regions, the data suggest the overlapping of the distal end (5'-TTA TGA) of toxA with the proximal end (5'-ATG AAT) of the LT subunit B gene (toxB), in the sequences 5'-TTATGAAT. Some additional characteristics of the LT operon as well as of the products are discussed.