Invasin

Invasins are a class of bacterial proteins associated with the penetration of pathogens into host cells. Invasins play a role in promoting entry during the initial stage of infection. In 2007, Als3 was identified as a fungal invasion allowing Candida albicans to infect host cells. Invasin is a small membrane bound protein that enables the infiltration of cultured mammalian cells by enteric bacteria. The cellular entry of invasin is facilitated through the binding of multiple β1 chain integrins. The interplay between invasin and β1 integrins initiates a reconfiguration of the cytoskeleton in the target cell, culminating in the creation of a groove and the internalization of bacteria through endosomes by the cell. Invasin is expressed inYersinia enterocolitica and Yersinia pseudotuberculosis because of its outermembrane being chromosomally encoded. Invasin demonstrates a significantly enhanced binding affinity to β1 integrins compared to the natural ligands of the receptor. More precisely, it forms a robust attachment to the α5β1 integrin, typically employed by fibronectin, exhibiting roughly 100 times greater strength. This heightened binding capability arises from structural disparities between the two proteins. The extracellular region of invasin adopts a rod-like configuration, with dimensions measuring approximately 180 Å by 30 Å by 30 Å.