InlB-dependent internalization of Listeria is mediated by the Met receptortyrosine kinase

The Listeria monocytogenes surface protein InlB promotes bacterial entry in to mammalian cells. Here, we identify a cellular surface receptor required for InlB-mediated entry. Treatment of mammalian cells with InlB protein or infection with L. monocytogenes induces rapid tyrosine phosphorylation of M et, a receptor tyrosine kinase (RTK) for which the only known ligand is Hep atocyte Growth Factor (HGF). Like HGF, InlB binds to the extracellular doma in of Met and induces "scattering" of epithelial cells. Experiments with Me t-positive and Met-deficient cell lines demonstrate that Met is required fo r InlB-dependent entry of L. monocytogenes. InlB is a novel Met agonist tha t induces bacterial entry through exploitation of a host RTK pathway.