The EspB protein of enterohaemorrhagic Escherichia coli interacts directly with alpha-catenin.

Enterohaemorrhagic Escherichia coli (EHEC) belongs to a family of pathogens that cause attaching and effacing (A/E) lesion on target cells. The EspB protein of EHEC is translocated both to the host cell cytoplasm and to the membrane, and is essential for the signalling events leading to A/E lesion. To determine the actual role of EspB in this process, we tried to identify the EspB binding partner of the host cell protein, using a yeast two-hybrid assay, and obtained a cytoskeletal-associated protein, alpha-catenin. The alpha-catenin bound directly to the N-terminal region of EspB, both in solid (overlay assay) and solution (pull-down assay) phases, and it was recruited to the EHEC adherence site, dependent on EspB. Expression of the N-terminal region of EspB, as well as the whole EspB in host cells, inhibited F-actin accumulation on the adherence site. We conclude that EspB recruits alpha-catenin at the EHEC adherence site by direct interaction, and that the recruitment of alpha-catenin is essential for EHEC-induced A/E lesion formation.