Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsutacho 4259, Midori-ku, Yokohama 226-8501, Japan.
Biochem Biophys Res Commun. 2010 Jan 15;391(3):1312-7. doi: 10.1016/j.bbrc.2009.12.023. Epub 2009 Dec 14.
Recent studies of the gliding bacteria Mycoplasma mobile have identified a family of proteins called the Gli family which was considered to be involved in this novel and yet fairly unknown motility system. The 349kDa protein called Gli349 was successfully isolated and purified from the bacteria, and electron microscopy imaging and antibody experiments led to the hypothesis that it acts as the "leg" of M. mobile, responsible for attachment to the substrate as well as for gliding motility. However, more precise evidence of the molecular shape and function of this protein was required to asses this theory any further. In this study, an atomic force microscope (AFM) was used both as an imaging and a force measurement device to provide new information about Gli349 and its role in gliding motility. AFM images of the protein were obtained revealing a complex structure with both rigid and flexible parts, consistent with previous electron micrographs of the protein. Single-molecular force spectroscopy experiments were also performed, revealing that Gli349 is able to specifically bind to sialyllactose molecules and withstand unbinding forces around 70pN. These findings strongly support the idea that Gli349 is the "leg" protein of M. mobile, responsible for binding and also most probably force generation during gliding motility.
最近对滑走细菌黏质支原体的研究鉴定了一组名为 Gli 家族的蛋白，它们被认为参与了这一新颖而鲜为人知的运动系统。一种名为 Gli349 的 349kDa 蛋白成功地从细菌中分离和纯化出来，电子显微镜成像和抗体实验提出假说，认为它是黏质支原体的“腿”，负责附着于基质以及滑行运动。然而，为了进一步评估这一理论，需要更精确的分子形状和功能证据。在这项研究中，原子力显微镜（AFM）既用作成像工具，也用作力测量工具，以提供有关 Gli349 及其在滑行运动中的作用的新信息。获得了该蛋白的 AFM 图像，揭示了一种具有刚性和柔性部分的复杂结构，与该蛋白的先前电子显微镜图像一致。还进行了单分子力谱实验，表明 Gli349 能够特异性结合唾液乳糖分子，并能承受约 70pN 的解联合力。这些发现有力地支持了 Gli349 是黏质支原体的“腿”蛋白的观点，它负责结合，并且很可能在滑行运动中产生力。
