A family of bacterial cysteine protease type III effectors utilizes acylation-dependent and -independent strategies to localize to plasma membranes.
A family of bacterial cysteine protease type III effectors utilizes acylation-dependent and -independent strategies to localize to plasma membranes.
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DOI：
10.1074/jbc.m900519200
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发表时间：
2009-06-05
期刊：
影响因子：
--
通讯作者：
Dixon JE
中科院分区：
文献类型：
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作者：
Dowen RH;Engel JL;Shao F;Ecker JR;Dixon JE
细菌植物病原体利用III型分泌系统将效应器蛋白输送到植物细胞中以抑制防御途径；然而，驱动效应器功能的分子机制和亚细胞定位策略在很大程度上仍然是一个谜。在这里，我们证明了植物质膜是丁香假单胞菌效应器AvrPphB和另外五个半胱氨酸蛋白酶家族成员的亚细胞定位的主要位置。AvrPphB和两个类似AvrPphB的效应器，ORF4和NOPT，在输送到植物细胞后自动蛋白分解处理，暴露嵌入的部位进行脂肪酰化。这三种效应物的宿主依赖性脂化作用直接影响质膜的定位，是AvrPphB无毒活性所必需的。令人惊讶的是，AvrPphB样效应器Ript、HopC1和HopN1利用一种不依赖于酰化的机制定位于细胞质膜。虽然一些AvrPphB样效应器使用酰化不依赖于酰化的定位策略，但另一些效应器劫持了真核脂化机制以确保质膜定位，说明了III型效应器使用的不同策略来靶向特定的亚细胞间隔。
Bacterial phytopathogens employ a type III secretion system to deliver effector proteins into the plant cell to suppress defense pathways; however, the molecular mechanisms and subcellular localization strategies that drive effector function largely remain a mystery. Here, we demonstrate that the plant plasma membrane is the primary site for subcellular localization of the Pseudomonas syringae effector AvrPphB and five additional cysteine protease family members. AvrPphB and two AvrPphB-like effectors, ORF4 and NopT, autoproteolytically process following delivery into the plant cell to expose embedded sites for fatty acylation. Host-dependent lipidation of these three effectors directs plasma membrane localization and is required for the avirulence activity of AvrPphB. Surprisingly, the AvrPphB-like effectors RipT, HopC1, and HopN1 utilize an acylation-independent mechanism to localize to the cellular plasma membrane. Although some AvrPphB-like effectors employ acylation-independent localization strategies, others hijack the eukaryotic lipidation machinery to ensure plasma membrane localization, illustrating the diverse tactics employed by type III effectors to target specific subcellular compartments.