A region of the Yersinia pseudotuberculosis invasin protein enhances integrin-mediated uptake into mammalian cells and promotes self-association

Invasin allows efficient entry into mammalian cells by Yersinia pseudotuber culosis. It has been shown that the C-terminal 192 amino acids of invasin a re essential for binding of beta(1) integrin receptors and subsequent uptak e. By analyzing the internalization of latex beads coated with invasin deri vatives, an additional domain of invasin was shown to be required for effic ient bacterial internalization, A monomeric derivative encompassing the C-t erminal 197 amino acids was inefficient at promoting entry of latex beads, whereas dimerization of this derivative by antibody significantly increased uptake. By using the DNA-binding domain of lambda repressor as a reporter for invasin self-interaction, we have demonstrated that a region of the inv asin protein located N-terminal to the cell adhesion domain of invasin is a ble to self-associate. Chemical crosslinking studies of purified and surfac e-exposed invasin proteins, and the dominant-interfering effect of a nonfun ctional invasin derivative are consistent with the presence of a self-assoc iation domain that is located within the region of invasin that enhances ba cterial uptake, We conclude that interaction of homomultimeric invasin with multiple integrins establishes tight adherence and receptor clustering, th us providing a signal for internalization.