Structure of a VirD4 coupling protein bound to a VirB type IV secretion machinery.
Structure of a VirD4 coupling protein bound to a VirB type IV secretion machinery.
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DOI：
10.15252/embj.201796629
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发表时间：
2017-10-16
期刊：
影响因子：
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通讯作者：
Waksman G
中科院分区：
文献类型：
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作者：
Redzej A;Ukleja M;Connery S;Trokter M;Felisberto-Rodrigues C;Cryar A;Thalassinos K;Hayward RD;Orlova EV;Waksman G
IV型分泌（T4S）系统是介导蛋白质和/或DNA运输的多功能细菌分泌系统。T4S系统一般由11个VirB蛋白和1个VirD蛋白（VirD4）组成。VirB1‐11蛋白组装形成分泌机制和菌毛，而VirD4蛋白负责底物募集。VirD4的分离结构是已知的；然而，其与VirB1‐11装置结合的结构尚未确定。在这里，我们纯化了一个带有VirD4结合的T4S系统，定义了复合物形成的生化要求，并描述了VirD4参与的蛋白质-蛋白质相互作用网络。我们还通过负染色电子显微镜解决了这个复合体的结构，证明了VirD4二聚体的两个拷贝位于仪器的两侧，在VirB4 atp酶之间。鉴于VirD4在IV型分泌中的核心作用，我们的研究为介导抗生素抗性基因在细菌群体中的危险传播过程提供了机制见解。
Type IV secretion (T4S) systems are versatile bacterial secretion systems mediating transport of protein and/or DNA. T4S systems are generally composed of 11 VirB proteins and 1 VirD protein (VirD4). The VirB1‐11 proteins assemble to form a secretion machinery and a pilus while the VirD4 protein is responsible for substrate recruitment. The structure of VirD4 in isolation is known; however, its structure bound to the VirB1‐11 apparatus has not been determined. Here, we purify a T4S system with VirD4 bound, define the biochemical requirements for complex formation and describe the protein–protein interaction network in which VirD4 is involved. We also solve the structure of this complex by negative stain electron microscopy, demonstrating that two copies of VirD4 dimers locate on both sides of the apparatus, in between the VirB4 ATPases. Given the central role of VirD4 in type IV secretion, our study provides mechanistic insights on a process that mediates the dangerous spread of antibiotic resistance genes among bacterial populations.