Type VI secretion system: secretion by a contractile nanomachine.
Type VI secretion system: secretion by a contractile nanomachine.
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DOI：
10.1098/rstb.2015.0021
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发表时间：
2015-10-05
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影响因子：
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通讯作者：
Basler M
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作者：
Basler M
六型分泌系统（T6SS）存在于大约四分之一的革兰氏阴性菌中。T6SS的几个关键成分在进化上与可收缩纳米机器（如噬菌体和r型脓毒蛋白）的成分相关。T6SS组装是由一种膜复合物的形成开始的，这种膜复合物结合了一个带有尖刺的噬菌体样底板，随后是一个长而坚硬的内管和一个外部收缩鞘的聚合。在装配过程中，效应器通过各种机制预加载到尖钉或管中。鞘的收缩释放出前所未有的能量，这些能量被用来将带有相关效应器的刺突和管冲出效应器细胞，并穿过细菌和真核靶细胞的膜。收缩鞘的亚单位被t6ss特异性展开酶回收，以允许新一轮的组装。活细胞成像表明，该组装是高度动态的，其亚细胞定位在某些细菌中具有显着的精度。通过效应物的作用，T6SS主要参与致病性和细菌间的竞争。本综述总结了有助于我们目前对T6SS作用方式的理解的知识。
The type VI secretion systems (T6SS) are present in about a quarter of all Gram-negative bacteria. Several key components of T6SS are evolutionarily related to components of contractile nanomachines such as phages and R-type pyocins. The T6SS assembly is initiated by formation of a membrane complex that binds a phage-like baseplate with a sharp spike, and this is followed by polymerization of a long rigid inner tube and an outer contractile sheath. Effectors are preloaded onto the spike or into the tube during the assembly by various mechanisms. Contraction of the sheath releases an unprecedented amount of energy, which is used to thrust the spike and tube with the associated effectors out of the effector cell and across membranes of both bacterial and eukaryotic target cells. Subunits of the contracted sheath are recycled by T6SS-specific unfoldase to allow for a new round of assembly. Live-cell imaging has shown that the assembly is highly dynamic and its subcellular localization is in certain bacteria regulated with a remarkable precision. Through the action of effectors, T6SS has mainly been shown to contribute to pathogenicity and competition between bacteria. This review summarizes the knowledge that has contributed to our current understanding of T6SS mode of action.