INVOLVEMENT OF FOCAL ADHESION KINASE IN INVASIN-MEDIATED UPTAKE

High-efficiency entry of the enteropathogenic bacterium Yersinia pseud otuberculosis into nonphagocytic cells is mediated by the bacterial ou ter membrane protein invasin, Invasin-mediated uptake requires high af finity binding of invasin to multiple beta 1 chain integrin receptors on the host eukaryotic cell. Previous studies using inhibitors have in dicated that high-efficiency uptake requires tyrosine kinase activity. In this paper we demonstrate a requirement for focal adhesion kinase (FAK) for invasin-mediated uptake. Overexpression of a dominant interf ering form of FAK reduced the amount of bacterial entry. Specifically, the autophosphorylation site of FAR, which is a reported site of c-Sr c kinase binding, is required for bacterial internalization, as overex pression of a derivative lacking the autophosphorylation site had a do minant interfering effect as well. Cultured cells expressing interferi ng variants of Src kinase also showed reduced bacterial uptake, demons trating the involvement of a Src-family kinase in invasin-promoted upt ake.