title: Identification of a host 14-3-3 Protein that Interacts with Xanthomonas effector AvrRxv.
abstract: AvrRxv is a member of a family of pathogen effectors present in pathogens of both plant and mammalian species. Xanthomonas campestris pv. vesicatoria strains carrying AvrRxv induce a hypersensitive response (HR) in the tomato cultivar Hawaii 7998. 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. These results demonstrate that the AvrRxv bacterial effector recruits 14-3-3 proteins for its function within host cells. AvrRxv homologues YopP and YopJ from Yersinia do not have AvrRxv-specific HR-inducing activity when delivered into tomato host cells by Agrobacterium. Although YopP itself cannot induce HR, its C-terminal domain containing the catalytic residues can replace that of AvrRxv in an AvrRxv-YopP chimera for HR-inducing activity. Phylogenetic analysis indicates that the sequences encoding the C-termini of family members are evolving independently from those encoding the N-termini. Our results support a model in which there are three functional domains in proteins of the family, translocation, interaction, and catalytic.
authors.affiliation: Crop Improvement and Utilization Unit, Western Regional Research Center, ARS USDA, 800 Buchanan Street, Albany, CA 94710, US.
authors.forename: Maureen
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authors.lastname: Whalen
authors.forename: Todd
authors.initials: T
authors.lastname: Richter
authors.forename: Kseniya
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authors.lastname: Zakhareyvich
authors.forename: Masayasu
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authors.lastname: Yoshikawa
authors.forename: Dana
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authors.lastname: Al-Azzeh
authors.forename: Adeshola
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authors.lastname: Mendoza
authors.forename: Christine Q
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authors.lastname: Morales
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authors.lastname: Klassen
authors.forename: Gina
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authors.lastname: Perez-Baron
authors.forename: Carole S
authors.initials: CS
authors.lastname: Toebe
authors.forename: Ageliki
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authors.lastname: Tzovolous
authors.forename: Emily
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authors.lastname: Gerstman
authors.forename: Erika
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authors.lastname: Evans
authors.forename: Cheryl
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authors.lastname: Thompson
authors.forename: Mary
authors.initials: M
authors.lastname: Lopez
authors.forename: Pamela C
authors.initials: PC
authors.lastname: Ronald