The VirB/D4 Type four secretion system (T4SS) is a bacterial multiprotein complex that spans the bacterial envelope, which mediates the translocation of T-DNA and effector virulence proteins into... Show moreThe VirB/D4 Type four secretion system (T4SS) is a bacterial multiprotein complex that spans the bacterial envelope, which mediates the translocation of T-DNA and effector virulence proteins into recipient cell. My research revealed that the Agrobacterium VirE3 and VirD2 proteins are effector proteins that are translocated by the Agrobacterium T4SS into host cells. The translocated effector protein VirF carries an N-terminal F-box domain. My research focused on the identification of the host proteins interacting with VirF. The capacity of VirF to interact in vivo with ASK1 and CUL1, indicates that VirF plays a role in planta as part of a SCF complex, most likely mediating the ubiquitination of proteins targeted for degradation via the proteasome. Five other protein interactors of VirF (PIFs) were identified using the yeast 2-hybrid system. These VirF interactors are involved in different cellular processes, such as in metabolic processes, and in defense and stress responses. This suggests that Agrobacterium may translocate an effector virulence protein into plant host cells, which mimics the function of an eukaryotic F-box protein (FBP) and thus can direct the host SCF E3 Ub-ligase to the relevant plant targets. Show less
