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
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
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DOI：
10.1105/tpc.109.066878
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发表时间：
2009-06-01
期刊：
影响因子：
11.6
通讯作者：
Chai, Jijie
中科院分区：
文献类型：
--
作者：
Dong, Jing;Xiao, Fangming;Chai, Jijie
番茄（Solanum lycopersicum）对细菌性斑点病的抗性在来自番茄假单胞菌致病变种（Pst）的两种序列无关的效应蛋白AvrPto或AvrPtoB中的任一种被宿主Pto激酶识别后被激活。Pto通过与Prf蛋白协同作用诱导Pst免疫。最近报道的AvrPto-Pto复合物的结构揭示了AvrPto与Pto的相互作用似乎减轻了Pto的抑制作用，允许Pto激活Prf。在此，我们以1.9埃的分辨率呈现AvrPtoB（残基121至205）的Pto结合结构域的晶体结构，并且以3.3埃的分辨率呈现AvrPtoB（121-205）-Pto复合物的晶体结构。AvrPtoB（121-205）表现出与AvrPto完全不同的三级折叠，并且其构象在与Pto结合时基本保持不变。与AvrPto-Pto一样，AvrPtoB-Pto复合体依赖于两个接口。这些接口之一是类似的两个复合物，虽然从两个效应蛋白的主要氨基酸序列是非常不同的。在另一个界面处的Pto中的氨基酸取代破坏AvrPtoB-Pto的相互作用，但不破坏AvrPto-Pto的相互作用。有趣的是，Pto中影响这种独特界面的取代也导致Pto独立于任一效应蛋白诱导Prf依赖性宿主细胞死亡。
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 angstrom and of the AvrPtoB(121-205)-Pto complex at a resolution of 3.3 angstrom. AvrPtoB(121-205) 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.