BIPA - A TYROSINE-PHOSPHORYLATED GTPASE THAT MEDIATES INTERACTIONS BETWEEN ENTEROPATHOGENIC ESCHERICHIA-COLI (EPEC) AND EPITHELIAL-CELLS

We report the functional characterization of BipA, a GTPase that under goes tyrosine phosphorylation in an enteropathogenic Escherichia coli (EPEC) strain. BipA(-) mutants adhere to cultured epithelial cells but fail to trigger the characteristic cytoskeletal rearrangements found in cells infected with wild-type EPEC. In contrast, increased expressi on of BipA enhances actin remodelling and results in the hyperformatio n of pseudopods. BipA appears to be the first example of a new class o f virulence regulator, as it also controls flagella-mediated cell moti lity and resistance to the antibacterial effects of a human host defen ce protein. Its striking sequence similarity to ribosome-binding elong ation factors suggests that it uses a novel mechanism to modulate gene expression.