Outer membrane adhesion factor multivalent adhesion molecule 7 initiates host cell binding during infection by gram-negative pathogens.

The initial binding of bacteria to host cells is crucial to the delivery of virulence factors and thus is a key determinant of the pathogen's success. We report a multivalent adhesion molecule (MAM) that enables a wide range of gram-negative pathogens to establish high-affinity binding to host cells during the early stages of infection. MAM7 binds to the host by engaging in both protein-protein (with fibronectin) and protein-lipid (with phosphatidic acid) interactions with the host cell membrane. We find that MAM7 expression on the outer membrane of a gram-negative pathogen is necessary for virulence in a nematode infection model and for efficient killing of cultured mammalian host cells. Expression of MAM7 on nonpathogenic strains produced a tool that can be used to impede infection by gram-negative bacterial pathogens. Targeting or exploiting MAM7 might prove to be important in combating gram-negative bacterial infections.