An asymmetric sheath controls flagellar supercoiling and motility in the leptospira spirochete
An asymmetric sheath controls flagellar supercoiling and motility in the leptospira spirochete
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DOI：
10.7554/elife.53672
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发表时间：
2020-03-10
期刊：
影响因子：
7.7
通讯作者：
Sindelar, Charles Vaughn
中科院分区：
文献类型：
--
作者：
Gibson, Kimberley H.;Trajtenberg, Felipe;Sindelar, Charles Vaughn
螺旋体细菌，包括重要的病原体，通过整个细胞的波动表现出独特的游泳方式。运动由超螺旋“内鞭毛”的旋转提供动力，该“内鞭毛”包裹着细胞体，限制在周质空间内。为了研究对运动至关重要的鞭毛超螺旋的结构基础，我们通过集成高分辨率冷冻电子断层扫描和 X 射线晶体学确定了螺旋体钩端螺旋体的天然鞭毛丝的结构。我们表明，这些细丝被高度不对称的多组分鞘层覆盖，与之前在外鞭毛细菌中观察到的仅鞭毛蛋白均聚物形成鲜明对比。不同的鞘蛋白定位于丝的内部和外部曲率以定义超螺旋几何形状，解释了这种螺旋体鞭毛的关键功能属性。
Spirochete bacteria, including important pathogens, exhibit a distinctive means of swimming via undulations of the entire cell. Motility is powered by the rotation of supercoiled 'endoflagella' that wrap around the cell body, confined within the periplasmic space. To investigate the structural basis of flagellar supercoiling, which is critical for motility, we determined the structure of native flagellar filaments from the spirochete Leptospira by integrating high-resolution cryo-electron tomography and X-ray crystallography. We show that these filaments are coated by a highly asymmetric, multi-component sheath layer, contrasting with flagellin-only homopolymers previously observed in exoflagellated bacteria. Distinct sheath proteins localize to the filament inner and outer curvatures to define the supercoiling geometry, explaining a key functional attribute of this spirochete flagellum.