Functional Activation of the Flagellar Type III Secretion Export Apparatus.
Functional Activation of the Flagellar Type III Secretion Export Apparatus.
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DOI：
10.1371/journal.pgen.1005443
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发表时间：
2015-08
期刊：
影响因子：
4.5
通讯作者：
Kearns DB
中科院分区：
文献类型：
--
作者：
Phillips AM;Calvo RA;Kearns DB
鞭毛由内向外依次组装，具有强制执行亚基添加的时间顺序的形态发生检查点。在这里，我们表明，鞭毛基体未能进行钩组装在高频率的枯草芽孢杆菌的单调蛋白SwrB的情况下。遗传抑制基因分析表明，SwrB激活鞭毛III型分泌输出装置的膜蛋白FliP。此外，突变体缺陷的鞭毛C-环表型，缺乏SwrB的减少钩频率和C-环缺陷可以绕过SwrB过表达或功能获得性等位基因在聚合结构域的FliG。我们得出结论，SwrB增强的概率，鞭毛基体采用精通分泌的构象，以确保杆和钩亚基不分泌的情况下，一个合适的平台上，以保证。细菌构建针状注射体以将毒素分泌到宿主细胞中，并构建螺旋桨状鞭毛以使用称为III型分泌系统（T3 SS）的分子机器在其环境中游动。注射体和鞭毛都是大的自组装复合物，T3 SS的调节确保蛋白质按顺序分泌以获得适当的结构和功能。在这里，我们报告的遗传和细胞学数据，枯草芽孢杆菌的SwrB蛋白帮助鞭毛的基础采取一个完整的构象，这反过来又激活封闭的T3 SS输出蛋白质的鞭毛组装的下一阶段。因此，SwrB提出了一种新的机制来监督早期结构检查点调节机组装。靶向功能调节因子如SwrB可以抑制病原体基于T3 SS的策略。
Flagella are assembled sequentially from the inside-out with morphogenetic checkpoints that enforce the temporal order of subunit addition. Here we show that flagellar basal bodies fail to proceed to hook assembly at high frequency in the absence of the monotopic protein SwrB of Bacillus subtilis. Genetic suppressor analysis indicates that SwrB activates the flagellar type III secretion export apparatus by the membrane protein FliP. Furthermore, mutants defective in the flagellar C-ring phenocopy the absence of SwrB for reduced hook frequency and C-ring defects may be bypassed either by SwrB overexpression or by a gain-of-function allele in the polymerization domain of FliG. We conclude that SwrB enhances the probability that the flagellar basal body adopts a conformation proficient for secretion to ensure that rod and hook subunits are not secreted in the absence of a suitable platform on which to polymerize. Bacteria build needle-like injectsomes to secrete toxins into host cells and build propeller-like flagella to swim through their environment using a molecular machine called the type III secretion system (T3SS). Both the injectisome and the flagellum are large self-assembling complexes and regulation of the T3SS ensures that proteins are secreted sequentially for proper structure and function. Here we report genetic and cytological data that the SwrB protein of Bacillus subtilis helps the base of the flagellum adopt a completed conformation which in turn activates the enclosed T3SS to export proteins for the next stage of flagellar assembly. Thus SwrB presents a novel mechanism to supervise an early structural checkpoint regulating machine assembly. Targeting functional regulators like SwrB could inhibit T3SS-based strategies of pathogens.