A bacterial E3 ubiquitin ligase targets a host protein kinase to disrupt plant immunity

Article

关键词: PROGRAMMED CELL-DEATH;    PATHOGEN PSEUDOMONAS-SYRINGAE;    III EFFECTORS;    DISEASE RESISTANCE;    INNATE IMMUNITY;    BASAL DEFENSE;    GENE FAMILY;    TOMATO;    PTO;    ARABIDOPSIS;   

DOI  :  10.1038/nature05966

来源: SCIE

【 摘 要 】

Many bacterial pathogens of plants and animals use a type III secretion system to deliver diverse virulence-associated 'effector' proteins into the host cell(1). The mechanisms by which these effectors act are mostly unknown; however, they often promote disease by suppressing host immunity(2). 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(3). Deletion of this domain allows an amino-terminal region of AvrPtoB (AvrPtoB(1-387)) to be detected by certain tomato varieties leading to immunity-associated programmed cell death(4). Here we show that a host kinase, Fen, physically interacts with AvrPtoB(1-387) 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 AvrPtoB(1-387) and not to full-length AvrPtoB. Thus, by acquiring an E3 ligase domain, AvrPtoB has thwarted a highly conserved host resistance mechanism.

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