Brevia

Cartwheel Architecture of Trichonympha Basal Body

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Science  12 Jul 2012:
1222789
DOI: 10.1126/science.1222789

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Abstract

Centrioles and basal bodies are essential for the formation of cilia, flagella, and centrosomes. Centrioles and basal bodies 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 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.

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