The Pseudomonas putida T6SS is a plant warden against phytopathogens.
The Pseudomonas putida T6SS is a plant warden against phytopathogens.
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DOI：
10.1038/ismej.2016.169
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发表时间：
2017-04
期刊：
影响因子：
--
通讯作者：
Llamas MA
中科院分区：
文献类型：
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作者：
Bernal P;Allsopp LP;Filloux A;Llamas MA
VI 型细菌分泌系统 (T6SS) 是一种分子武器，旨在将有毒效应物传递到猎物细胞中。这些纳米机器在细菌间竞争中发挥着重要作用，并为多微生物环境中的 T6SS 活性菌株提供了优势。在这里，我们分析了生物防治剂恶臭假单胞菌 KT2440 的基因组，并鉴定了三个 T6SS 基因簇（K1-、K2- 和 K3-T6SS）。此外，还发现了 10 个 T6SS 效应子-免疫对，包括假定的核酸酶和成孔大肠杆菌素。我们证明 K1-T6SS 是一种有效的抗菌装置，它分泌有毒的 Rhs 型效应物 Tke2。值得注意的是，恶臭假单胞菌以 K1-T6SS 依赖性方式根除多种细菌，包括有弹性的植物病原体，这表明 T6SS 有助于增强恶臭假单胞菌对抗竞争对手的能力。此外，我们观察到在恶臭假单胞菌和野油菜黄单胞菌共同感染期间，本氏烟草叶子上的坏死显着减少。这种保护取决于恶臭假单胞菌 T6SS 的活性。人们已经探索了许多途径来开发能够操纵根际和叶际微生物组成的生物防治剂。在这里，我们揭示了一种新的植物生物防治机制，在选择以预防植物病原体感染为使命的植物管理员时需要考虑该机制。
Bacterial type VI secretion systems (T6SSs) are molecular weapons designed to deliver toxic effectors into prey cells. These nanomachines have an important role in inter-bacterial competition and provide advantages to T6SS active strains in polymicrobial environments. Here we analyze the genome of the biocontrol agent Pseudomonas putida KT2440 and identify three T6SS gene clusters (K1-, K2- and K3-T6SS). Besides, 10 T6SS effector–immunity pairs were found, including putative nucleases and pore-forming colicins. We show that the K1-T6SS is a potent antibacterial device, which secretes a toxic Rhs-type effector Tke2. Remarkably, P. putida eradicates a broad range of bacteria in a K1-T6SS-dependent manner, including resilient phytopathogens, which demonstrates that the T6SS is instrumental to empower P. putida to fight against competitors. Furthermore, we observed a drastically reduced necrosis on the leaves of Nicotiana benthamiana during co-infection with P. putida and Xanthomonas campestris. Such protection is dependent on the activity of the P. putida T6SS. Many routes have been explored to develop biocontrol agents capable of manipulating the microbial composition of the rhizosphere and phyllosphere. Here we unveil a novel mechanism for plant biocontrol, which needs to be considered for the selection of plant wardens whose mission is to prevent phytopathogen infections.