Conformity between heat-labile toxin genes from human and porcine enterotoxigenic Escherichia coli

The genes encoding the heat-labile toxin of Escherichia coli were isolated by recombinant DNA methods from enterotoxigenic E. coli recovered from a human and a piglet with diarrhea. With restriction endonucleases, a fine-structure map was made for the toxin genes. Both genes were found to be highly homologous within the toxin-coding DNA, but the surrounding DNA sequences were found to be quite divergent. Analysis of in vitro-derived mutants demonstrated that the cistrons for the toxin proteins were located at the same sites on each restriction enzyme map.