热门: 生物工程 生物技术 生物科学 高中生物 微生物 海洋生物 生物学 细胞
原始出处:
Nature 449, 243-247 (13 September 2007) | doi:10.1038/nature06109; Received 5 July 2007; Accepted 24 July 2007; Published online 12 August 2007
The structural basis for activation of plant immunity by bacterial effector protein AvrPto
Weiman Xing1,2, Yan Zou1,3,6, Qun Liu4,6, Jianing Liu1, Xi Luo1, Qingqiu Huang3, She Chen1, Lihuang Zhu3, Ruchang Bi2, Quan Hao4, Jia-Wei Wu5, Jian-Min Zhou1 & Jijie Chai1
Correspondence to: Jijie Chai1 Correspondence and requests for materials should be addressed to J.C. (Email: chaijijie@nibs.ac.cn).
Pathogenic microbes use effectors to enhance susceptibility in host plants. However, plants have evolved a sophisticated immune system to detect these effectors using cognate disease resistance proteins1, a recognition that is highly specific, often elicits rapid and localized cell death, known as a hypersensitive response, and thus potentially limits pathogen growth2, 3, 4, 5. Despite numerous genetic and biochemical studies on the interactions between pathogen effector proteins and plant resistance proteins, the structural bases for such interactions remain elusive. The direct interaction between the tomato protein kinase Pto and the Pseudomonas syringae effector protein AvrPto is known to trigger disease resistance and programmed cell death6, 7 through the nucleotide-binding site/leucine-rich repeat (NBS-LRR) class of disease resistance protein Prf8. Here we present the crystal structure of an AvrPto–Pto complex. Contrary to the widely held hypothesis that AvrPto activates Pto kinase activity, our structural and biochemical analyses demonstrated that AvrPto is an inhibitor of Pto kinase in vitro. The AvrPto–Pto interaction is mediated by the phosphorylation-stabilized P+1 loop and a second loop in Pto, both of which negatively regulate the Prf-mediated defences in the absence of AvrPto in tomato plants. Together, our results show that AvrPto derepresses host defences by interacting with the two defence-inhibition loops of Pto.