Repression of heat-stable enterotoxin synthesis in enterotoxigenic Escherichia coli.
Five different carbon sources were examined for their ability to control synthesis of heat-stable enterotoxin (ST) by enterotoxigenic (ENT+) Escherichia coli grown in either a defined medium containing four amino acids or a minimal salts medium. No ST activity was observed when D-glucose, D-gluconate, and L-arabinose were added separately to the defined medium, whereas glycerol and pyruvate decreased toxin levels. Similar results were obtained using a minimal salts medium, except with pyruvate, which did not support growth. Inhibition of ST synthesis by D-glucose was overcome by the addition of 3 X 10(-3) M cyclic adenosine 3',5'-monophosphate. Glucose repression of beta-galactosidase synthesis under conditions optimal for inhibition of ST synthesis was also reversed by exogenous cyclic adenosine 3',5'-monophosphate in the presence of the inducer isopropyl-beta-D-thiogalactopyranoside. The data suggest that control mechanisms for the synthesis of plasmid gene products of bacterial pathogens are similar to those exerted on the host chromosome.
D000242:Cyclic AMP / Q000494:pharmacology; D004768:Enterotoxins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D001616:beta-Galactosidase / Q000096:biosynthesis
D004768:Enterotoxins; D000242:Cyclic AMP; D001616:beta-Galactosidase