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English

バクテリア鞭毛フックの構造と、分子ユニバーサルジョイントとしての動作のしくみ

論文誌情報 Nature 431, 1062-8 (2004)

* 論文のコメント: Molecular motors: smooth coupling in Salmonella by Surridge C.
著者 Samatey FA, Matsunami H, Imada K, Nagashima S, Shaikh TR, Thomas DR, Chen JZ, Derosier DJ, Kitao A, Namba K
論文タイトル Structure of the bacterial flagellar hook and implication for the molecular universal joint mechanism.
PubMed 15510139
研究室HP 日本電子YOKOGUSHI協働研究所〈難波特任教授〉

Figure1:Stereo view of the C backbone ...

要旨

The bacterial flagellum is a motile organelle, and the flagellar hook is a short, highly curved tubular structure that connects the flagellar motor to the long filament acting as a helical propeller. The hook is made of about 120 copies of a single protein, FlgE, and its function as a nano-sized universal joint is essential for dynamic and efficient bacterial motility and taxis. It transmits the motor torque to the helical propeller over a wide range of its orientation for swimming and tumbling. Here we report a partial atomic model of the hook obtained by X-ray crystallography of FlgE31, a major proteolytic fragment of FlgE lacking unfolded terminal regions, and by electron cryomicroscopy and three-dimensional helical image reconstruction of the hook. The model reveals the intricate molecular interactions and a plausible switching mechanism for the hook to be flexible in bending but rigid against twisting for its universal joint function.

namba2004-Fig1.jpg Figure1:Stereo view of the C backbone trace of FlgE31. The chain is colour-coded from blue to red, going through the rainbow colours, from the N terminus to the C terminus. The model is oriented with domain D1 at the bottom and D2 at the top. Domain D1 shows a stack of four -hairpins on the left and a triangular loop on the front right. namba2004-Fig2-1.jpg Figure2:Docking of the atomic model of FlgE31 into the outer two domains of the hook (End-on view).