Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2008
Publication Date: 9/12/2008
Citation: Whalen, M.C., Richter, T., Zakhareyvich, K., Yoshikawa, M., Al-Azzeh, D., Adefioye, A., Spicer, G., Mendoza, L.L., Morales, C.Q., Klassen, V., Perez-Baron, G., Toebe, C.S., Tzovolous, A., Gerstman, E., Evans, E., Thompson, C., Lopez, M., Ronald, P.C. 2008. Identification of a host 14-3-3 Protein that Interacts with Xanthomonas effector AvrRxv. Physiological and Molecular Plant Pathology. 72:46-55. Interpretive Summary: Bacterial pathogens of plants and mammals inject proteins into host cells. These proteins, called effectors, disrupt normal cellular function. One such effector from a bacterial pathogen of tomato and pepper, is AvrRxv. AvrRxv is a member of a family of pathogen effectors from both plant and mammalian pathogens. In this study, in addition to further characterizing the molecular genetic nature of avrRxv, we analyzed the function of AvrRxv family members. AvrRxv induces a resistance response on a particular tomato line. We analyzed the AvrRxv-specific resistance-inducing activity of AvrRxv family members YopP and YopJ from the mammalian pathogen Yersinia. Although YopP itself cannot induce resistance, part of the protein that contains important amino acids for protease function can, in fact, replace that of AvrRxv for resistance-inducing activity. In addition, we identified a protein from tomato that physically interacts with AvrRxv called ARI1 (for AvrRxv Interacting 1). We identified a ARI1-binding domain in AvrRxv that is necessary not only for binding, but also for resistance-inducing activity.
Technical Abstract: AvrRxv is a member of a family of pathogen effectors from both plant and mammalian pathogens. Using a yeast two hybrid screen, we identified a 14-3-3 protein from tomato that interacts with AvrRxv called AvrRxv Interactor 1 (ARI1). The interaction was confirmed in vitro with affinity chromatography. Using mutagenesis, we identified a 14-3-3-binding domain in AvrRxv and demonstrated that a mutant in that domain showed concomitant loss of interaction with ARI1 and HR-inducing activity in tomato. AvrRxv homologues YopP and YopJ from Yersinia do not have AvrRxv-specific HR-inducing activity when delivered to host cells by Agrobacterium. Although YopP itself cannot induce HR, its C-terminal domain containing the protease catalytic residues can replace that of AvrRxv in an AvrRxv-YopP chimera for HR-inducing activity. The transcription initiation site of avrRxv was identified.