Synthesis and Secretion of the Plasmid-Coded Heat-Labile Enterotoxin of Escherichia coli in Vibrio cholerae

Both cholera toxin and heat-labile enterotoxin were made and secreted into culture supernatants by Vibrio cholerae containing the enterotoxin plasmid pCG86. Several regulatory mutations in V. cholerae that increased or decreased the synthesis of cholera toxin did not affect production of heat-labile enterotoxin. In contrast, a mutation in V. cholerae that interfered with the secretion of cholera toxin also decreased the secretion of heat-labile enterotoxin, indicating that they are processed by a common secretory pathway. Vibrio cholerae should be useful as a model system for analyzing the secretion of true extracellular proteins by Gram-negative bacteria.