THE LOCUS OF ENTEROCYTE EFFACEMENT PATHOGENICITY ISLAND OF ENTEROPATHOGENIC ESCHERICHIA-COLI ENCODES SECRETION FUNCTIONS AND REMNANTS OF TRANSPOSONS AT ITS EXTREME-RIGHT END

The locus of enterocyte effacement (LEE) is necessary for enteropathog enic Escherichia coli to cause characteristic attaching and effacing l esions in host cells. To determine whether sequences at the extreme ri ght end of the LEE downstream of the espB gene are required for attach ing and effacing, we constructed a mutant with an Omega-interposon ins ertion immediately downstream of espB. This mutant is incapable of att aching and effacing, of secreting EspA and EspB and of inducing tyrosi ne phosphorylation of host cell proteins. These phenotypes are restore d by a plasmid containing the extreme right end of the LEE. The nucleo tide sequence of this region reveals a relatively low G+C content, rem nants of transposons, and several open reading frames. The predicted p roducts of these open reading frames include a potential chaperone, a potential component of the secretion apparatus, and a hypothetical pep tide with proline rich repeats reminiscent of several eukaryotic prote ins. These data indicate that the extreme right end of the LEE is requ ired for attaching and effacing and reveal information relevant to the origin and function of the LEE.