YopD

YopD is a protein component of the type III secretion system (T3SS) used by pathogenic Yersinia species, including Yersinia pestis, Y. enterocolitica, and Y. pseudotuberculosis. It is part of the translocon that forms a pore in host cell membranes to enable the injection of bacterial effector proteins (Yops).

Functionally, YopD works in concert with the pore-forming protein YopB to create the translocation channel. The YopB–YopD complex is believed to insert into the host cell membrane after contact with host cells, providing a conduit through which Yersinia delivers Yops into the cytosol of the host cell. This translocation is a key step in the virulence of Yersinia, and mutations or defects in yopD reduce translocation efficiency and virulence in experimental models.

YopD is encoded within the yop operon and its expression is coordinated with other T3SS components by the Yersinia virulence regulatory network. Secretion and translocon assembly are tightly regulated and typically induced by host-like cues, such as contact with host cells and physiological temperature, enabling timely effector delivery.

Biochemically, YopD interacts with YopB and other translocon components and can be found associated with secreted complexes during translocation. The precise localization and orientation of YopD relative to the host membrane are topics of ongoing research.

Clinical significance: YopD contributes to the pathogenicity of Yersinia infections by enabling efficient effector delivery. Disruption of yopD impairs translocation and attenuates virulence in experimental settings, underscoring its role as a component of the Yersinia T3SS translocon.