Petre Benjamin, Lorrain Cécile, Saunders Diane G O, Win Joe, Sklenar Jan, Duplessis Sébastien, Kamoun Sophien
The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK.
INRA, UMR 1136 Interactions Arbres/Microorganismes, Centre INRA Nancy Lorraine, Champenoux, 54280, France.
Cell Microbiol. 2016 Apr;18(4):453-65. doi: 10.1111/cmi.12530. Epub 2015 Nov 10.
Parasite effector proteins target various host cell compartments to alter host processes and promote infection. How effectors cross membrane-rich interfaces to reach these compartments is a major question in effector biology. Growing evidence suggests that effectors use molecular mimicry to subvert host cell machinery for protein sorting. We recently identified chloroplast-targeted protein 1 (CTP1), a candidate effector from the poplar leaf rust fungus Melampsora larici-populina that carries a predicted transit peptide and accumulates in chloroplasts and mitochondria. Here, we show that the CTP1 transit peptide is necessary and sufficient for accumulation in the stroma of chloroplasts. CTP1 is part of a Melampsora-specific family of polymorphic secreted proteins. Two members of that family, CTP2 and CTP3, also translocate in chloroplasts in an N-terminal signal-dependent manner. CTP1, CTP2 and CTP3 are cleaved when they accumulate in chloroplasts, while they remain intact when they do not translocate into chloroplasts. Our findings reveal that fungi have evolved effector proteins that mimic plant-specific sorting signals to traffic within plant cells.
寄生虫效应蛋白靶向宿主细胞的各个区室，以改变宿主生理过程并促进感染。效应蛋白如何穿过富含膜的界面到达这些区室是效应生物学中的一个主要问题。越来越多的证据表明，效应蛋白利用分子模拟来颠覆宿主细胞用于蛋白质分选的机制。我们最近鉴定出叶绿体靶向蛋白1（CTP1），它是来自杨叶锈病菌（Melampsora larici-populina）的一种候选效应蛋白，带有一个预测的转运肽，并在叶绿体和线粒体中积累。在此，我们表明CTP1转运肽对于在叶绿体基质中积累是必要且充分的。CTP1是一个杨叶锈病菌特异性的多态性分泌蛋白家族的成员。该家族的两个成员CTP2和CTP3也以N端信号依赖的方式转运到叶绿体中。CTP1、CTP2和CTP3在叶绿体中积累时会被切割，而当它们不转运到叶绿体中时则保持完整。我们的研究结果表明，真菌已经进化出效应蛋白，这些蛋白模拟植物特异性的分选信号以便在植物细胞内运输。
