Unraveling the Self-Assembly of the Pseudomonas aeruginosa XcpQ Secretin Periplasmic Domain Provides New Molecular Insights into Type II Secretion System Secreton Architecture and Dynamics.
Unraveling the Self-Assembly of the Pseudomonas aeruginosa XcpQ Secretin Periplasmic Domain Provides New Molecular Insights into Type II Secretion System Secreton Architecture and Dynamics.
复制标题
DOI：
10.1128/mbio.01185-17
复制
发表时间：
2017-10-17
期刊：
影响因子：
6.4
通讯作者：
Voulhoux R
中科院分区：
文献类型：
--
作者：
Douzi B;Trinh NTT;Michel-Souzy S;Desmyter A;Ball G;Barbier P;Kosta A;Durand E;Forest KT;Cambillau C;Roussel A;Voulhoux R
II型分泌系统(T2SS)在许多革兰氏阴性病原体的包膜上释放大量折叠的外源蛋白。因此，这种分泌过程需要特定的门控、相互作用和动力学特性，主要由称为分泌素的两部分外膜通道操作。我们对分泌素的成孔C末端结构与功能的关系有了很好的了解。相反，其周质N-末端结构域的高度灵活性一直是获得揭示其分子功能所需的详细结构信息的障碍。在铜绿假单胞菌中，XCP T2SS通过将大量毒素和降解酶输送到周围环境中，在细菌毒力中发挥重要作用。在这里，我们揭示了XcpQ的N-末端结构域自发地自组装成一个独立于其C-末端结构域的六聚体。此外，利用多学科方法，我们阐明了XcpQ N结构域的结构组织，并证明了分泌素在二聚体间界面的灵活性是其功能所必需的。细菌分泌素是一种大的同源低聚蛋白质，构成了几种包膜嵌入的纳米机器的外膜造孔元件，对细菌的生存和致病至关重要。它们包括一个明确的膜包埋C-末端结构域和一个模块化的周质N-末端结构域，参与底物募集和与内膜成分的连接。我们正在研究铜绿假单胞菌中存在的T2SS的XcpQ分泌素。我们的数据强调了XcpQ N-末端结构域自发寡聚成六聚体的能力。进一步的体内实验表明，该结构域在T2SS的分泌过程中采用了不同的构象。这些发现为理解细菌T2SS分泌素的功能提供了新的见解。
The type II secretion system (T2SS) releases large folded exoproteins across the envelope of many Gram-negative pathogens. This secretion process therefore requires specific gating, interacting, and dynamics properties mainly operated by a bipartite outer membrane channel called secretin. We have a good understanding of the structure-function relationship of the pore-forming C-terminal domain of secretins. In contrast, the high flexibility of their periplasmic N-terminal domain has been an obstacle in obtaining the detailed structural information required to uncover its molecular function. In Pseudomonas aeruginosa, the Xcp T2SS plays an important role in bacterial virulence by its capacity to deliver a large panel of toxins and degradative enzymes into the surrounding environment. Here, we revealed that the N-terminal domain of XcpQ secretin spontaneously self-assembled into a hexamer of dimers independently of its C-terminal domain. Furthermore, and by using multidisciplinary approaches, we elucidate the structural organization of the XcpQ N domain and demonstrate that secretin flexibility at interdimer interfaces is mandatory for its function. Bacterial secretins are large homooligomeric proteins constituting the outer membrane pore-forming element of several envelope-embedded nanomachines essential in bacterial survival and pathogenicity. They comprise a well-defined membrane-embedded C-terminal domain and a modular periplasmic N-terminal domain involved in substrate recruitment and connection with inner membrane components. We are studying the XcpQ secretin of the T2SS present in the pathogenic bacterium Pseudomonas aeruginosa. Our data highlight the ability of the XcpQ N-terminal domain to spontaneously oligomerize into a hexamer of dimers. Further in vivo experiments revealed that this domain adopts different conformations essential for the T2SS secretion process. These findings provide new insights into the functional understanding of bacterial T2SS secretins.