Architecture, Function, and Substrates of the Type II Secretion System.
Architecture, Function, and Substrates of the Type II Secretion System.
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DOI：
10.1128/ecosalplus.esp-0034-2018
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发表时间：
2019-02-01
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影响因子：
--
通讯作者：
Sandkvist, Maria
中科院分区：
文献类型：
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作者：
Korotkov, Konstantin V;Sandkvist, Maria
II型分泌系统(T2SS)将毒素和一系列水解酶，包括蛋白酶、脂肪酶和碳水化合物活性酶，输送到革兰氏阴性细菌的细胞表面或细胞外空间。它对细胞外和细胞内的病原体以及环境中的变形杆菌的生存的贡献是显而易见的。这种动态的、多组分的机制横跨整个细胞被膜，由细胞质ATPase、几个内膜蛋白、周质假性纤毛和嵌入外膜的分泌素孔组成。尽管T2S纳米机器具有跨包膜结构，但一旦通过SEC或TAT输出系统进入周质隔室，将被分泌的蛋白质首先与系统接触。因此，T2SS专用于它们的外膜转位。T2SS和IV型菌毛之间的许多序列和结构上的相似之处表明它们有共同的起源，并论证了菌毛介导的分泌机制。这篇综述描述了单个T2SS组件的结构、功能和相互作用，以及组装的T2SS机器的总体结构，并简要总结了越来越多的T2SS外源蛋白的运输和功能。强调了冷冻电子显微镜的最新进展，这使得人们对分泌素通道和假乳头的结构-功能关系有了更多的了解。
The type II secretion system (T2SS) delivers toxins and a range of hydrolytic enzymes, including proteases, lipases, and carbohydrate-active enzymes, to the cell surface or extracellular space of Gram-negative bacteria. Its contribution to survival of both extracellular and intracellular pathogens as well as environmental species of proteobacteria is evident. This dynamic, multicomponent machinery spans the entire cell envelope and consists of a cytoplasmic ATPase, several inner membrane proteins, a periplasmic pseudopilus, and a secretin pore embedded in the outer membrane. Despite the trans-envelope configuration of the T2S nanomachine, proteins to be secreted engage with the system first once they enter the periplasmic compartment via the Sec or TAT export system. Thus, the T2SS is specifically dedicated to their outer membrane translocation. The many sequence and structural similarities between the T2SS and type IV pili suggest a common origin and argue for a pilus-mediated mechanism of secretion. This minireview describes the structures, functions, and interactions of the individual T2SS components and the general architecture of the assembled T2SS machinery and briefly summarizes the transport and function of a growing list of T2SS exoproteins. Recent advances in cryo-electron microscopy, which have led to an increased understanding of the structure-function relationship of the secretin channel and the pseudopilus, are emphasized.