Modulation of Rho GTPases and the actin cytoskeleton by Yersinia outer proteins (Yops)

Pathogenic species of the genus Yersinia employ a type III secretion appara tus to inject up to six effector proteins (Yersinia outer proteins; Yops) i nto host cells. Thereby yersiniae disarm the immune cell system of the host to proliferate extracellularly. At least four of the Yop effectors (YopE, YpkA/YopO, YopT and YopH) are involved in the rearrangement of the actin cy toskeleton: YopE, YopT and YpkA/YopO modulate the activity of actin-regulat ing Rho GTP-binding proteins, whereas YopH dephosphorylates phospho-tyrosin e residues in focal adhesion proteins. In this review we will focus on rece nt evidence implicating Rho GTPases and the actin cytoskeleton as major tar gets of Yersinia Yops.