Swiss Institute for Experimental Cancer Research, School of Life Sciences, Swiss Federal Institute of Technology, Lausanne, Switzerland.
Science. 2012 Aug 3;337(6094):553. doi: 10.1126/science.1222789. Epub 2012 Jul 12.
Centrioles and basal bodies are essential for the formation of cilia, flagella, and centrosomes. They exhibit a characteristic ninefold symmetry imparted by a cartwheel thought to contain rings of SAS-6 proteins. We used cryoelectron tomography to investigate the architecture of the exceptionally long cartwheel of the flagellate Trichonympha. We found that the cartwheel is a stack of central rings that exhibit a vertical periodicity of 8.5 nanometers and is able to accommodate nine SAS-6 homodimers. The spokes that emanate from two such rings associate into a layer, with a vertical periodicity of 17 nanometers on the cartwheel margin. Thus, by using the power of biodiversity, we unveiled the architecture of the cartwheel at the root of the ninefold symmetry of centrioles and basal bodies.
中心粒和基体对于纤毛、鞭毛和中心体的形成是必不可少的。它们表现出一种由辐轮结构赋予的特征性九倍对称性，辐轮结构被认为包含 SAS-6 蛋白的环。我们使用冷冻电子断层扫描技术研究了鞭毛虫 Trichonympha 的异常长辐轮的结构。我们发现辐轮是中央环的堆叠，具有 8.5 纳米的垂直周期性，能够容纳九个 SAS-6 同源二聚体。从两个这样的环发出的辐条结合成一层，在辐轮边缘具有 17 纳米的垂直周期性。因此，通过利用生物多样性的力量，我们揭示了位于中心粒和基体九倍对称性根源的辐轮结构。
