Attaching and effacing of host cells by enteropathogenic Escherichia coli in the absence of detectable tyrosine kinase mediated signal transduction.

An unusual mutant of enteropathogenic E. coli (EPEC), deficient in its ability to invade host cells, was evaluated. The gene interrupted by the transposon in this mutant was located within a region of the EPEC chromosome devoted to secretion of proteins required for signal transduction. The mutant did not secrete detectable levels of the EspB protein, previously shown to be required for attaching and effacing, and did not induce detectable tyrosine phosphorylation of a 90 kDa host cell protein, previously associated with attaching and effacing and invasion. No quantitative or qualitative defect in the ability of the mutant to induce attaching and effacing effects was observed. Moreover, attaching and effacing by wild-type EPEC was unaffected by high doses of the tyrosine kinase inhibitor genistein. These results indicate that attaching and effacing activity can occur in the absence of detectable EspB secretion and tyrosine kinase mediated signal transduction.