2009年6月9日，北京生命科学研究所柴继杰实验室在Plant Cell杂志上在线发表题为“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。该文章首次报道了细菌效应蛋白AvrPtoB和植物中对应的抗性蛋白Pto复合物AvrPtoB-Pto的晶体结构，揭示了同一个植物抗性蛋白（Pto）如何识别两个完全不同的细菌效应蛋白（AvrPto 和AvrPtoB）的分子机制。
植物的抗性蛋白精确识别病原菌中的效应蛋白,对引发植物防御响应非常重要。植物的抗性蛋白Pto能够识别两个序列完全不同源的效应蛋白AvrPto和AvrPtoB，并通过NB-LRR蛋白Prf激活下游免疫反应。文章解析了AvrPtoB的Pto-binding domain（AvrPtoB 121-205）的晶体结构（1.9埃），以及AvrPtoB121-205-Pto复合物的结构（3.3埃）。该复合物的晶体结构揭示了AvrPtoB与Pto相互作用通过两个界面调节，其中一个界面与AvrPto-Pto复合物的结合面完全不同。实验表明，替换了位于这个界面上氨基酸的Pto，不需要效应蛋白AvrPto或AvrPtoB ，就能引发Prf介导的免疫反应。该结果进一步证实了效应蛋白通过解除Pto对植物抗病的抑制作用从而引起宿主免疫反应。同时，文章从结构的角度揭示了同一个植物抗性蛋白（Pto）如何识别不同细菌效应蛋白的分子机制。
该文章的共同第一作者董靖是北京生命科学研究所和中国科学院生物物理研究所联合培养的博士生，共同第一作者樊粉霞是北京生命科学研究所和北京师范大学联合招生的博士生，论文其他的作者还有论文的其他作者还有：共同第一作者Fangming Xiao，谷立川博士，仓怀兴博士 。北京生命科学研究所的柴继杰博士和康奈尔大学的Gregory B. Martin为本文共同通讯作者。此项研究为科技部863和北京市科委资助课题，结构与生化部分工作在北京生命科学研究所完成。（生物谷Bioon.com）
生物谷推荐原始出处：
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.
