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- Title
A bacterial E3 ubiquitin ligase targets a host protein kinase to disrupt plant immunity.
- Authors
Rosebrock, Tracy R.; Lirong Zeng; Brady, Jennifer J.; Abramovitch, Robert B.; Fangming Xiao; Martin, Gregory B.
- Abstract
Many bacterial pathogens of plants and animals use a type III secretion system to deliver diverse virulence-associated ‘effector’ proteins into the host cell. The mechanisms by which these effectors act are mostly unknown; however, they often promote disease by suppressing host immunity. One type III effector, AvrPtoB, expressed by the plant pathogen Pseudomonas syringae pv. tomato, has a carboxy-terminal domain that is an E3 ubiquitin ligase. Deletion of this domain allows an amino-terminal region of AvrPtoB (AvrPtoB1–387) to be detected by certain tomato varieties leading to immunity-associated programmed cell death. Here we show that a host kinase, Fen, physically interacts with AvrPtoB1–387 and is responsible for activating the plant immune response. The AvrPtoB E3 ligase specifically ubiquitinates Fen and promotes its degradation in a proteasome-dependent manner. This degradation leads to disease susceptibility in Fen-expressing tomato lines. Various wild species of tomato were found to exhibit immunity in response to AvrPtoB1–387 and not to full-length AvrPtoB. Thus, by acquiring an E3 ligase domain, AvrPtoB has thwarted a highly conserved host resistance mechanism.
- Subjects
UBIQUITIN; PROTEINS; LIGASES; ENZYMES; IMMUNITY; PHYTOPATHOGENIC microorganisms; PSEUDOMONAS syringae; POTATOES
- Publication
Nature, 2007, Vol 448, Issue 7151, p370
- ISSN
0028-0836
- Publication type
Article
- DOI
10.1038/nature05966