Yersinia type III effectors perturb host innate immune responses

Core Tip

Core tip: The study of Yersinia type III secretion system effector proteins has provided critical insights into bacterial pathogenic strategies and host innate immune responses. Identification of the crystal structure of YpkA revealed how a bacterial effector can counteract phagocytosis at multiple levels including inhibition of actin polymerization by sequestering actin, inhibition of actin signaling molecules via both its kinase and dissociation-like inhibitor domains, and inhibition of actin-cytoskeletal components via phosphorylation. YpkA/YopO multisite autophosphorylation may allow YpkA/YopO to bypass regulation by host phosphatases and thus prolong its ability to interfere with phagocytosis. Additionally, an emerging theme is the role of caspases in anti-Yersinia host defenses.