Enterotoxins of Escherichia coli and vibriocholerae: tools for the molecular biologist.

With the independent discovery in several different laboratories that Vibrio cholerae and heat-labile Escherichia coli enterotoxins activated an enzyme (adenylate cyclase) in small intestinal epithealial cells to cause an enhanced intestinal secretion mediated by cyclic adenosine 3',5'-monophosphate (cyclic AMP), a molecular mechanism was provided for these disease states. As agents that also elevate intracellular concentrations of cyclic AMP in virtually every mammalian tissue tested, the enterotoxins are potentially invaluable tools in investigation of the molecular sequence of events of all cyclic AMP-related cellular phenomena. Cyclic AMP has been known for some time to be the central regulator in the cellular expression of the effects of hormones and has become known more recently as an agent that controls cellular growth by corrdinately influencing several biochemical processes related to rate of cell division. Successful application of the enterotoxins as cellular probes in the areas of regulation of cell division, determination of the reaction mechanism of adenylate cyclase, and elucidation of the relationship between prostaglandin and adenylate cyclase, both in this laboratory and in those of others, is reviewed.