Identification of a protein secretory pathway for the secretion of heat-labile enterotoxin by an enterotoxigenic strain of Escherichia coli

Abstract

Enterotoxigenic Escherichia coli (ETEC) is an enteric pathogen that causes cholera-like diarrhea in humans and animals. ETEC secretes a heat-labile enterotoxin (LT), which resembles cholera toxin, but the actual mechanism of LT secretion is presently unknown. We have identified a previously unrecognized type II protein secretion pathway in the prototypic human ETEC strain, H10407 (serotype 078:H11). The genes for this pathway are absent from E. coli K-12, although examination of the K-12 genome suggests that it probably once possessed them. The secretory pathway bears significant homology at the amino acid level to the type II protein secretory pathway required by Vibrio cholerae for the sec..