Poster: Plant-pathogen interactions
Abs #
578: An Assay for Protein Transport from Agrobacterium to the Host Plant Cell
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Presenter: |
Vaidya, Manjusha , mvaidya@notes.cc.sunysb.edu | Authors | Vaidya, Manjusha (A) Lacorix, Benoit (A) Vainstein, Alexander (B) Tzfira, Tzvi (A) Citovsky, Vitaly (A) | | Affiliations: |
(A): Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 1794-5215
(B): Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel
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Agrobacterium exports its T-DNA along with a series of virulence (Vir) proteins to the plant cell. The transported Vir proteins play roles in such critical steps of infection as T-DNA nuclear import and its integration into the plant genome. But does Agrobacterium export additional proteins that participate in the infection process? Furthermore, the Agrobacterium-to-plant cell protein transport is mediated by specific signal sequences within the exported protein. Can such signals be used to tag and export foreign proteins from the bacterium to the host cell? To address these questions, we developed a system to monitor protein export from the bacterium to plant cells. Our system is based on the transgenic Arabidopsis plants carrying GUS reporter driven by the UAS-GAL4 promoter which is induced by a chimeric protein composed of the GAL4-DNA binding domain (GAL4DBD) and the VP16 transcriptional activator. When these plants were inoculated with Agrobacterium expressing GAL4DBD-VP16 no GUS expression was observed, indicating that GAL4DBD-VP16 was not transported from Agrobacterium to the plant cells. However, inoculation with Agrobacterium expressing GAL4DBD-VP16 fused to VirE2 resulted in GUS expression, indicating transport of the fusion protein from the bacterium to the plant cell. Moreover, when the GAL4DBD-VP16 fused with GFP or with the Arabidopsis VIP1 protein were tagged with the export signal of VirE2, they were also transported into plant cells, demonstrating that Agrobacterium can translocate foreign proteins, into the host cell. Interestingly, the GAL4DBD-VP16-GFP fusion was transported into the host cell even without the export signal, suggesting that some, but not all, small proteins may pass the VirB/VirD4 channel independent of an export signal.
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