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Mechanical properties of bacterial hook filament

细菌钩丝的力学性能

基本信息

批准号：
17340126
负责人：
YOSHIMURA Hideyuki
金额：
$ 10.55万
依托单位：
Meiji University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17340126/
关键词：
flagella polyhook Young's modulus rigidity fluorescence electronmicroscopy rapid freezing freeze dry レーザトラップ

项目摘要

Flagellated bacteria like Sal. Typhimurium swims by rotating helical flagella filaments with bundling and synchronizing them each other. Because axs of bacterial motors directed in different way, flexible joint part is required between motor and flagella filament. It is known that bacterial hook work as a universal joint of this part. However its mechanical feature like rigidity is not known exactly. Here we measured modulus of rigidity by using polyhook filament, length about 1μm, from mutant Sal. Typhimurium(SWJ108). Purified polyhook filaments were frozen rapidly in liquid ethane and freeze dried. Distribution of helix pitch and diameter were evaluated from electron micrographs of shadowed images. We got value of 95±23nm for helix pitch and 31±9.9nm for diameter of polyhook filament. We also measured fluctuation of helical pitch and diameter of flagella filament from negative stained samples. By comparing fluctuation of polyhook and flagella filaments, we have calculated the ratio of rigidity as G_<flagella>/G<hook>=120. According to the literature value of flagella filament rigidity, 3.8×10^9Pa, we obtained rigidity of polyhook as 3.3×10^7Pa. We also tried to measure the rigidity of flagella in solution directly using thin glass capillary. Fluorescent labeled flagella filament was fixed by anti-flagellin adsorbed on a glass capillary of diameter less than 1μm. Tension in pN range was measured from bending deformation of glass capillary under fluorescent microscope. We are now accumulating the results in this process. We are going to measure rigidity of super-poly hook which has length of few micro-meter by the same method.

像萨尔这样有鞭毛的细菌。鼠伤寒沙门氏菌通过旋转螺旋鞭毛细丝和束并使它们彼此同步来游泳。由于细菌电机的轴向方向不同，电机和鞭毛细丝之间需要灵活的连接件。众所周知，细菌钩是这一部件的万向节。然而，它的力学特性，如刚性，还不是很清楚。在这里，我们用来自突变体SAL的长度约1μm的多钩纤维测量刚性系数。鼠伤寒杆菌(SWJ108)。将提纯的多钩纤维在液态乙烷中快速冷冻并冷冻干燥。从阴影图像的电子显微镜照片中评估螺旋节距和直径的分布。螺旋螺距为95±23 nm，多钩丝直径为31±9.9 nm。我们还测量了负染样本鞭毛的螺旋节距和直径的波动。通过比较多钩细丝和鞭毛细丝的波动，我们计算出刚性比G_&lt；鞭毛&gt；/G&lt；钩&gt；=120。根据文献测得的鞭毛细丝硬度为3.8×10~(-9)PA，得到多钩纤维的刚度为3.3×10~(-7)PA。我们还尝试了用薄玻璃毛细管直接测定溶液中鞭毛的硬度。用吸附在直径小于1μm的玻璃毛细管上的抗鞭毛蛋白固定荧光标记的鞭毛细丝，在荧光显微镜下通过玻璃毛细管的弯曲变形测量PN范围内的张力。我们现在正在积累这个过程中的结果。我们将用同样的方法测量长度为几微米的超聚合钩的刚性。