Role of the Dc domain of the bacterial hook protein FlgE in hook assembly and function.
Role of the Dc domain of the bacterial hook protein FlgE in hook assembly and function.
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DOI：
10.2142/biophysics.9.63
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Namba K
中科院分区：
文献类型：
--
作者：
Moriya N;Minamino T;Ferris HU;Morimoto YV;Ashihara M;Kato T;Namba K
细菌鞭毛钩起到万向节的作用，将电机产生的扭矩平稳地传递给灯丝。钩蛋白FlgE在钩帽(FlgD)的帮助下组装成55 nm的管状结构。FlgE由D0、Dc、D1和D2四个结构域组成，从钩的管状结构的内到外排列。DC结构域有助于挂钩的结构稳定性，但尚不清楚该DC结构域如何影响万向关节机制。在这里，我们进行了FlgE DC结构域的缺失分析。缺失30~49个残基的FlgEΔ4/5不能分泌到培养基中。残基分别为40-49和50-59缺失的FlgEΔ5和FlgEΔ6仍然形成挂钩，使出口装置能够输出钩丝连接蛋白FlgK和FlgL以及鞭毛蛋白Flc。然而，这些缺失抑制了钩端FlgD钩帽被FlgK取代，从而取消了细丝的形成。50-59位残基的缺失显著影响钩的形态。这些结果表明，DC结构域不仅负责钩子的组装，还负责FlgE的输出、与FlgK的相互作用以及钩子的多态超螺旋机制。
The bacterial flagellar hook acts as a universal joint to smoothly transmit torque produced by the motor to the filament. The hook protein FlgE assembles into a 55 nm tubular structure with the help of the hook cap (FlgD). FlgE consists of four domains, D0, Dc, D1 and D2, arranged from the inner to the outer part of the tubular structure of the hook. The Dc domain contributes to the structural stability of the hook, but it is unclear how this Dc domain is responsible for the universal joint mechanism. Here, we carried out a deletion analysis of the FlgE Dc domain. FlgEΔ4/5 with deletion of residues 30 to 49 was not secreted into the culture media. FlgEΔ5 and FlgEΔ6 with deletions of residues 40 to 49 and 50 to 59, respectively, still formed hooks, allowing the export apparatus to export the hook-filament junction proteins FlgK and FlgL and flagellin FliC. However, these deletions inhibited the replacement of the FlgD hook cap by FlgK at the hook tip, thereby abolishing filament formation. Deletion of residues 50 to 59 significantly affected hook morphology. These results suggest that the Dc domain is responsible not only for hook assembly but also for FlgE export, the interaction with FlgK, and the polymorphic supercoiling mechanism of the hook.