2009年6月9日,，北京生命科學研究所柴繼杰實驗室在Plant Cell雜志上在線發(fā)表題為“Crystal structure of the complex between Pseudomonas effector AvrPtoB and the Pto tomato kinase reveals both a shared and a unique interface compared with AvrPto-Pto”的文章,。該文章首次報道了細菌效應蛋白AvrPtoB和植物中對應的抗性蛋白Pto復合物AvrPtoB-Pto的晶體結(jié)構(gòu)，揭示了同一個植物抗性蛋白（Pto）如何識別兩個完全不同的細菌效應蛋白（AvrPto 和AvrPtoB）的分子機制。

植物的抗性蛋白精確識別病原菌中的效應蛋白,對引發(fā)植物防御響應非常重要。植物的抗性蛋白Pto能夠識別兩個序列完全不同源的效應蛋白AvrPto和AvrPtoB，并通過NB-LRR蛋白Prf激活下游免疫反應,。文章解析了AvrPtoB的Pto-binding domain（AvrPtoB 121-205）的晶體結(jié)構(gòu)（1.9埃）,，以及AvrPtoB121-205-Pto復合物的結(jié)構(gòu)（3.3埃）。該復合物的晶體結(jié)構(gòu)揭示了AvrPtoB與Pto相互作用通過兩個界面調(diào)節(jié),，其中一個界面與AvrPto-Pto復合物的結(jié)合面完全不同,。實驗表明，替換了位于這個界面上氨基酸的Pto,，不需要效應蛋白AvrPto或AvrPtoB ,，就能引發(fā)Prf介導的免疫反應。該結(jié)果進一步證實了效應蛋白通過解除Pto對植物抗病的抑制作用從而引起宿主免疫反應,。同時,，文章從結(jié)構(gòu)的角度揭示了同一個植物抗性蛋白（Pto）如何識別不同細菌效應蛋白的分子機制。

該文章的共同第一作者董靖是北京生命科學研究所和中國科學院生物物理研究所聯(lián)合培養(yǎng)的博士生,，共同第一作者樊粉霞是北京生命科學研究所和北京師范大學聯(lián)合招生的博士生,，論文其他的作者還有論文的其他作者還有：共同第一作者Fangming Xiao，谷立川博士,，倉懷興博士 ,。北京生命科學研究所的柴繼杰博士和康奈爾大學的Gregory B. Martin為本文共同通訊作者。此項研究為科技部863和北京市科委資助課題,，結(jié)構(gòu)與生化部分工作在北京生命科學研究所完成,。（生物谷Bioon.com）

生物谷推薦原始出處：

Plant Cell June 9, 2009; 10.1105/tpc.109.066878

Crystal Structure of the Complex between Pseudomonas Effector AvrPtoB and the Tomato Pto Kinase Reveals Both a Shared and a Unique Interface Compared with AvrPto-Pto

Jing Dong 1, Fangming Xiao 2, Fenxia Fan 3, Lichuan Gu 4, Huaixing Cang 5, Gregory B. Martin 6, and Jijie Chai 7*

1 Institute of Biophysics, Chinese Academy of Sciences, Beijing 100875, China; National Institute of Biological Sciences, Beijing 102206, China
2 Boyce Thompson Institute for Plant Research, Ithaca, New York 14853; Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho 83844-3052
3 National Institute of Biological Sciences, Beijing 102206, China; College of Life Science, Beijing Normal University, Beijing 100875, China
4 State Key Lab of Microbial Technology, Shandong University, Jinan 250100, China
5 Institute of Biophysics, Chinese Academy of Sciences, Beijing 100875, China
6 Boyce Thompson Institute for Plant Research, Ithaca, New York 14853; Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York 14853
7 National Institute of Biological Sciences, Beijing 102206, China; Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China

Resistance to bacterial speck disease in tomato (Solanum lycopersicum) is activated upon recognition by the host Pto kinase of either one of two sequence-unrelated effector proteins, AvrPto or AvrPtoB, from Pseudomonas syringae pv tomato (Pst). Pto induces Pst immunity by acting in concert with the Prf protein. The recently reported structure of the AvrPto-Pto complex revealed that interaction of AvrPto with Pto appears to relieve an inhibitory effect of Pto, allowing Pto to activate Prf. Here, we present the crystal structure of the Pto binding domain of AvrPtoB (residues 121 to 205) at a resolution of 1.9? and of the AvrPtoB121-205–Pto complex at a resolution of 3.3 ?. AvrPtoB121-205 exhibits a tertiary fold that is completely different from that of AvrPto, and its conformation remains largely unchanged upon binding to Pto. In common with AvrPto-Pto, the AvrPtoB-Pto complex relies on two interfaces. One of these interfaces is similar in both complexes, although the primary amino acid sequences from the two effector proteins are very different. Amino acid substitutions in Pto at the other interface disrupt the interaction of AvrPtoB-Pto but not that of AvrPto-Pto. Interestingly, substitutions in Pto affecting this unique interface also cause Pto to induce Prf-dependent host cell death independently of either effector protein.