Evading plant immunity: feedback control of the T3SS in Pseudomonas syringae.
Evading plant immunity: feedback control of the T3SS in Pseudomonas syringae.
复制标题
DOI：
10.15698/mic2017.04.570
复制
发表时间：
2017-03-17
期刊：
影响因子：
--
通讯作者：
Buck M
中科院分区：
文献类型：
--
作者：
Waite C;Schumacher J;Jovanovic M;Bennett M;Buck M
在小麦、水稻和玉米等主要农作物中，微生物造成的产量损失占全球产量损失的10%以上。了解使细菌植物病原体能够逃避宿主免疫系统并导致疾病的决策策略，对于管理它们对粮食安全日益增长的威胁至关重要。许多植物利用针状的III型分泌系统(T3SS)，通过将抑制真核信号通路的效应蛋白注入宿主细胞细胞质来抑制植物免疫。植物反过来可以通过识别和阻断T3SS效应器来进化对特定病原体的抗性，从而导致病原体和寄主之间正在进行的共同进化的“军备竞赛”。胞外功能Sigma因子HrpL协调T3SS调节子在叶栖丁香假单胞菌和类似病原菌中的表达。最近，我们发现，由于调控元件的重叠，HrpL与hrpL基因直接相邻的靶启动子的结合对其自身的表达水平施加了负的自身控制。我们的结果表明，通过下调T3SS功能，这种微调机制使紫丁香能够最大限度地减少效应器介导的植物免疫激发。
Microbes are responsible for over 10% of the global yield losses in staple crops such as wheat, rice, and maize. Understanding the decision-making strategies that enable bacterial plant pathogens to evade the host immune system and cause disease is essential for managing their ever growing threat to food security. Many utilise the needle-like type III secretion system (T3SS) to suppress plant immunity, by injecting effector proteins that inhibit eukaryotic signalling pathways into the host cell cytoplasm. Plants can in turn evolve resistance to specific pathogens via recognition and blocking of the T3SS effectors, so leading to an ongoing co-evolutionary ‘arms race’ between pathogen and host pairs. The extracytoplasmic function sigma factor HrpL co-ordinates the expression of the T3SS regulon in the leaf-dwelling Pseudomonas syringae and similar pathogens. Recently, we showed that association of HrpL with a target promoter directly adjacent to the hrpL gene imposes negative autogenous control on its own expression level due to overlapping regulatory elements. Our results suggest that by down-regulating T3SS function, this fine-tuning mechanism enables P. syringae to minimise effector-mediated elicitation of plant immunity.