Structural and Functional Characterization of the Bacterial Type III Secretion Export Apparatus.
Structural and Functional Characterization of the Bacterial Type III Secretion Export Apparatus.
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DOI：
10.1371/journal.ppat.1006071
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发表时间：
2016-12
期刊：
影响因子：
6.7
通讯作者：
Wagner S
中科院分区：
文献类型：
--
作者：
Dietsche T;Tesfazgi Mebrhatu M;Brunner MJ;Abrusci P;Yan J;Franz-Wachtel M;Schärfe C;Zilkenat S;Grin I;Galán JE;Kohlbacher O;Lea S;Macek B;Marlovits TC;Robinson CV;Wagner S
细菌III型蛋白分泌系统将效应蛋白注入真核宿主细胞，以促进革兰氏阴性病原体和共生菌的生存和定植。通过细菌细胞膜的分泌和注入宿主细胞是由所谓的注射体促进的。它的疏水输出装置小成分Spap和Spar被证明能使针状复合体的组装成核，并形成鼠伤寒沙门氏菌分泌系统的中央“杯”亚结构。然而，这些成分在体内的针状复合体中的位置及其在分泌过程中的功能仍然不清楚。在这里，我们提供了Spap五聚体形成15？宽的孔的证据，并提供了Spap与出口设备组件SpaQ、Spar和SPA相互作用的详细图。我们进一步提炼了输出装置组装的当前视图，巩固了SPAP和SPAR的跨膜拓扑模型，并展示了SPAP和SPAR的周质结构域与内杆蛋白PrgJ的密切相互作用，表明输出装置和针丝是如何连接在一起的，为底物转运创造了一条连续的管道。许多革兰氏阴性菌使用III型分泌系统将细菌蛋白注入真核宿主细胞，以促进自身的生存和定植。这些系统是大型分子机器，能够一步跨越三个细胞膜运输蛋白质。人们认为，这些系统唯一的门控屏障存在于细菌的细胞质膜中，但到目前为止，还不清楚这个门是什么样子的，它是由哪些成分组成的。在这里，我们提出了基于深入的生化和遗传特征的证据，即在沙门氏菌致病性岛1的III型分泌系统的细胞膜上，5个Spap蛋白的组装形成了这个门。我们进一步证明，SpaQ、Spar和SpA各有一个亚基与Spap门密切相关，并可能在门控机制中发挥作用，并且PrgJ蛋白在外部附着在这个门上，将其连接到向宿主细胞伸出的中空针丝。我们的发现阐明了III型分泌系统到目前为止定义不清的一个方面，并可能有助于开发针对这些毒力相关分子设备的新型抗感染疗法。
Bacterial type III protein secretion systems inject effector proteins into eukaryotic host cells in order to promote survival and colonization of Gram-negative pathogens and symbionts. Secretion across the bacterial cell envelope and injection into host cells is facilitated by a so-called injectisome. Its small hydrophobic export apparatus components SpaP and SpaR were shown to nucleate assembly of the needle complex and to form the central “cup” substructure of a Salmonella Typhimurium secretion system. However, the in vivo placement of these components in the needle complex and their function during the secretion process remained poorly defined. Here we present evidence that a SpaP pentamer forms a 15 Å wide pore and provide a detailed map of SpaP interactions with the export apparatus components SpaQ, SpaR, and SpaS. We further refine the current view of export apparatus assembly, consolidate transmembrane topology models for SpaP and SpaR, and present intimate interactions of the periplasmic domains of SpaP and SpaR with the inner rod protein PrgJ, indicating how export apparatus and needle filament are connected to create a continuous conduit for substrate translocation. Many Gram-negative bacteria use type III secretion systems to inject bacterial proteins into eukaryotic host cells in order to promote their own survival and colonization. These systems are large molecular machines with the ability to transport proteins across three cell membranes in one step. It is believed that the only gated barrier of these systems lies in the bacterial cytoplasmic membrane but it was unclear so far how this gate looks like and of which components it is composed. Here we present evidence based on in depth biochemical and genetic characterization that an assembly of five SpaP proteins forms this gate in the cytoplasmic membrane of the type III secretion system of Salmonella pathogenicity island 1. We further show that one subunit each of the proteins SpaQ, SpaR, and SpaS are closely associated to the SpaP gate and may function in the gating mechanism, and that the protein PrgJ is attached to this gate on the outside to connect it to the hollow needle filament projecting towards the host cell. Our findings elucidate a hitherto ill-defined aspect of type III secretion systems and may help to develop novel antiinfective therapies targeting these virulence-associated molecular devices.
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影响因子：
6.4
作者：
Monjarás Feria JV;Lefebre MD;Stierhof YD;Galán JE;Wagner S
通讯作者：
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4.4
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