Refining the structure of the Halobacterium salinarum flagellar filament using the iterative helical real space reconstruction method: insights into polymorphism.
Refining the structure of the Halobacterium salinarum flagellar filament using the iterative helical real space reconstruction method: insights into polymorphism.
复制标题
使用迭代螺旋真实空间重建方法细化盐杆菌鞭毛丝的结构：对多态性的见解。
DOI：
10.1016/j.jmb.2004.12.010
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Egelman,EdwardH
中科院分区：
文献类型：
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作者：
Trachtenberg,Shlomo;Galkin,VitoldE;Egelman,EdwardH
真细菌鞭毛丝是一种外部的、自组装的、螺旋状的聚合物，其直径为220 μ m，由高度保守的单体鞭毛蛋白构成，鞭毛蛋白在远端外部聚合。古生菌丝的直径只有100 μ m，在近端组装，由不同的糖基化鞭毛蛋白构成。虽然游动的现象与真细菌相似，但古细菌丝状体的对称性却完全不同。在这里，我们扩展了我们以前的研究鞭毛螺旋丝结构的菌株R1 M1盐杆菌。我们使用了盐藻的菌株M175，它以高产率形成多鞭毛束，在相对低的离子强度（0.8M对5 M）和低pH（0.25对0.68）的条件下，多鞭毛束形成直的细丝。我们以前证明了单粒子方法的螺旋重建有许多优势，传统的傅立叶-贝塞尔方法处理可变螺旋对称性和异质性。我们在这里表明，当这种方法被应用到古细菌展开鞭毛丝的有序螺旋结构，显着的扩展分辨率时，可以很容易地获得相比，应用传统的螺旋技术。丝群体可以分成不同形态的类别，其可以代表多晶型状态。使用冷冻负染色图像，已实现10-15 μ m的分辨率。单个α-螺旋可以适合于重建，支持所提出的与IV型细菌皮利的结构相似性。
The eubacterial flagellar filament is an external, self-assembling, helical polymer ∼220Å in diameter constructed from a highly conserved monomer, flagellin, which polymerizes externally at the distal end. The archaeal filament is only ∼100Å in diameter, assembles at the proximal end and is constructed from different, glycosylated flagellins. Although the phenomenology of swimming is similar to that of eubacteria, the symmetry of the archebacterial filament is entirely different. Here, we extend our previous study on the flagellar coiled filament structure of strain R1M1 of Halobacterium salinarum. We use strain M175 of H.salinarum, which forms poly-flagellar bundles at high yield which, under conditions of relatively low ionic-strength (0.8M versus 5M) and low pH (∼2.5 versus ∼6.8), form straight filaments. We demonstrated previously that a single-particle approach to helical reconstruction has many advantages over conventional Fourier–Bessel methods when dealing with variable helical symmetry and heterogeneity. We show here that when this method is applied to the ordered helical structure of the archebacterial uncoiled flagellar filament, significant extensions in resolution can be obtained readily when compared to applying traditional helical techniques. The filament population can be separated into classes of different morphologies, which may represent polymorphic states. Using cryo-negatively stained images, a resolution of ∼10–15Å has been achieved. Single α-helices can be fit into the reconstruction, supporting the proposed similarity of the structure to that of type IV bacterial pili.