Type VI Secretion System Toxins Horizontally Shared between Marine Bacteria.
Type VI Secretion System Toxins Horizontally Shared between Marine Bacteria.
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DOI：
10.1371/journal.ppat.1005128
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发表时间：
2015-08
期刊：
影响因子：
6.7
通讯作者：
Orth K
中科院分区：
文献类型：
--
作者：
Salomon D;Klimko JA;Trudgian DC;Kinch LN;Grishin NV;Mirzaei H;Orth K
VI型分泌系统（T6SS）是一种广泛存在的蛋白质分泌装置，用于革兰氏阴性菌将毒性效应蛋白传递到邻近的细菌或宿主细胞中。在这里，我们发现了海洋病原体褐藻溶解弧菌编码的两个t6ss在细菌间竞争中的作用。利用比较蛋白质组学和遗传学，我们确定了它们的效应库。除了前面描述的效应物V12G01_02265外，我们还发现了T6SS1分泌的三个新的效应物，这表明T6SS1至少分泌四种抗菌效应物，其中三种是MIX-effector类的成员。我们还发现T6SS2分泌至少三种抗菌效应物。我们的研究结果表明，许多属于V族的mix效应器是“孤儿”效应器，它们与可移动元件相邻，并通过水平基因转移在海洋细菌之间共享。我们证明了来自溶藻弧菌的MIX v效应在另一种弧菌中异位表达时是一种功能性的T6SS效应。我们提出移动MIX v效应器作为T6SS效应器的环境储存库，这些效应器被共享并用于使海洋细菌的抗菌毒素库多样化，从而增强竞争适应度。细菌VI型分泌系统（T6SS）是一种依赖于接触的蛋白质分泌装置，是环境中细菌间竞争的主要组成部分。溶藻弧菌是海洋动物的一种病原体，也是人类伤口感染、中耳炎和胃肠炎的致病因子。在这项研究中，我们提供了在该病原体中发现的两种t6ss的环境调节，抗菌活性和分泌效应谱的综合表征。我们还确定了T6SS效应物的一个子集，这些效应物似乎是可移动的，并且在水生环境中可以相互作用的海洋细菌之间共享。我们的研究结果表明，细菌可以吸收环境中竞争对手的T6SS效应物。这些新获得的毒素可用于扩大和多样化T6SS效应库并增强细菌适应性。
The type VI secretion system (T6SS) is a widespread protein secretion apparatus used by Gram-negative bacteria to deliver toxic effector proteins into adjacent bacterial or host cells. Here, we uncovered a role in interbacterial competition for the two T6SSs encoded by the marine pathogen Vibrio alginolyticus. Using comparative proteomics and genetics, we identified their effector repertoires. In addition to the previously described effector V12G01_02265, we identified three new effectors secreted by T6SS1, indicating that the T6SS1 secretes at least four antibacterial effectors, of which three are members of the MIX-effector class. We also showed that the T6SS2 secretes at least three antibacterial effectors. Our findings revealed that many MIX-effectors belonging to clan V are “orphan” effectors that neighbor mobile elements and are shared between marine bacteria via horizontal gene transfer. We demonstrated that a MIX V-effector from V. alginolyticus is a functional T6SS effector when ectopically expressed in another Vibrio species. We propose that mobile MIX V-effectors serve as an environmental reservoir of T6SS effectors that are shared and used to diversify antibacterial toxin repertoires in marine bacteria, resulting in enhanced competitive fitness. The bacterial type VI secretion system (T6SS) is a contact-dependent protein secretion apparatus that is emerging as a major component of interbacterial competition in the environment. The bacterium Vibrio alginolyticus is a pathogen of marine animals and a causal agent of wound infections, otitis, and gastroenteritis in humans. In this study, we provide a comprehensive characterization of the environmental regulation, antibacterial activities, and secreted effector repertoires of the two T6SSs found in this pathogen. We also identify a subset of T6SS effectors that appear to be mobile and shared between marine bacteria that can interact with each other in aquatic environments. Our findings suggest that bacteria can incorporate T6SS effectors from competitors in the environment. These newly acquired toxins may be used to expand and diversify T6SS effector repertoires and enhance bacterial fitness.