Agrobacterium tumefaciens is a gram-negative soil bacterium that induces plant tumors by transferring a segment of DNA, called T-DNA, into plant cells. Under laboratory conditions, Agrobacterium... Show moreAgrobacterium tumefaciens is a gram-negative soil bacterium that induces plant tumors by transferring a segment of DNA, called T-DNA, into plant cells. Under laboratory conditions, Agrobacterium can also transform many different non-plant organisms such as the yeast Saccharomyces cerevisiae. During this process, a number of virulence proteins, including VirF and VirE3, are translocated into the host cell. VirF contains an F-box domain and, according to current theory, in plants and in yeast may induce degradation of the virulence protein VirE2 and the transcription factor VIP1, required for the integration of the T-DNA into host chromosomal DNA. VirE3 functions as a potential plant transcriptional activator. In our study, we expressed the Agrobacterium virulence proteins VirF and VirE3 in Saccharomyces cerevisiae and Arabidopsis thaliana and studied the effect of virF and virE3 expression on the genome-wide transcription in S. cerevisiae and A.thaliana using DNA microarrays and RNA-sequencing. Show less
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
