Structure of the Core of the Type Three Secretion System Export Apparatus
Structure of the Core of the Type Three Secretion System Export Apparatus
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DOI：
10.1101/249128
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发表时间：
2018-01
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通讯作者：
L. Kuhlen;P. Abrusci;Steven Johnson;J. Gault;J. Deme;Joseph J. E. Caesar;Tobias Dietsche;M. T. Mebrhatu;T. Ganief;B. Maček;Samuel Wagner;C. Robinson;S. Lea
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作者：
L. Kuhlen;P. Abrusci;Steven Johnson;J. Gault;J. Deme;Joseph J. E. Caesar;Tobias Dietsche;M. T. Mebrhatu;T. Ganief;B. Maček;Samuel Wagner;C. Robinson;S. Lea
通过三型分泌系统输出蛋白质对于许多主要细菌病原体的细菌运动和毒力至关重要。三种假定的整合膜蛋白（FliP/FliQ/FliR）被认为形成内膜出口门的核心，但它们在最终纳米机器中的结构、组装和位置仍不清楚。我们在这里通过冷冻电子显微镜展示了这种 4.2 Å 复合物的结构。这些亚基均不采用规范的完整膜蛋白拓扑结构，并且常见的螺旋-转角-螺旋结构元件使它们能够形成化学计量比为 5:4:1 的螺旋组装体。将结构拟合到完整分泌系统的重建中，将输出门定位为机器周质部分的核心组件，并且交联实验证实了这一观察结果。因此，这项研究将输出门确定为分泌通道的关键元件，并暗示它启动了下游组装组件的螺旋结构。一句话总结 T3SS出口门的核心形成超膜螺旋组件
Export of proteins through type three secretion systems is critical for bacterial motility and virulence of many major bacterial pathogens. Three putative integral membrane proteins (FliP/FliQ/FliR) are suggested to form the core of an export gate in the inner membrane, but their structure, assembly and location within the final nanomachine remain unclear. We here present the structure of this complex at 4.2 Å by cryo-electron microscopy. None of the subunits adopt canonical integral membrane protein topologies and common helix-turn-helix structural elements allow them to form a helical assembly with 5:4:1 stoichiometry. Fitting of the structure into reconstructions of intact secretion systems localize the export gate as a core component of the periplasmic portion of the machinery, and cross-linking experiments confirm this observation. This study thereby identifies the export gate as a key element of the secretion channel and implies that it primes the helical architecture of the components assembling downstream. One Sentence Summary The core of the T3SS export gate forms a supra-membrane helical assembly