Carbon dioxide regulated secretion of the EaeB protein of enteropathogenic Escherichia coli.

An eaeA mutant (intimin deficient) of enteropathogenic Escherichia coli stimulated phosphorylation of several host cell proteins, showing that intimate adherence is not required to activate signal transduction pathways in enteropathogenic E. coli-infected cells. Growth of enteropathogenic E. coli in tissue culture medium in 5% CO2, in the presence or absence of cultured cells, resulted in the secretion of several bacterial proteins. Two of these, 36 kDa and 20 kDa in size, were expressed at significantly lower levels in air. N-terminal sequencing and analysis of secreted proteins of an eaeB mutant indicated that the 36 kDa secreted protein was EaeB, previously implicated in the stimulation of signalling pathways in enteropathogenic E. coli-infected cells.