Mechanism of activation adenylate cyclase in vitro by polymyxin-released, heat-labile enterotoxin of Escherichia coli.

Heat-labile enterotoxic material released from Escherichia coli by polymyxin B activates the adenylate cyclase of pigeon erythrocyte ghosts in a time- and concentration-dependent manner. The activation requires nicotinamide adenine dinucleotide, adenosine triphosphate, and another component of the erythrocyte supernatant. The active species has a molecular weight of about 23,000-24,000 daltons, is inhibited by antibodies to the toxin of Vibrio cholerae, and is not irreversibly denatured by sodium dodecyl sulfate. Thus in many respects the active species from E. coli behaves the same as peptide A1 of cholera toxin.