Architecture of the centriole cartwheel-containing region revealed by cryo-electron tomography
Résumé
Centrioles are evolutionarily conserved barrels of microtubule triplets that form the core of the centrosome and the base of the cilium. While the crucial role of the proximal region in centriole biogenesis has been well documented, its native architecture and evolutionary conservation remain relatively unexplored. Here, using cryo-electron tomography of centrioles from four evolutionarily distant species, we report on the architectural diversity of the centriole's proximal cartwheel-bearing region. Our work reveals that the cartwheel central hub is constructed from a stack of paired rings with cartwheel inner densities inside. In bothParameciumandChlamydomonas, the repeating structural unit of the cartwheel has a periodicity of 25 nm and consists of three ring pairs, with 6 radial spokes emanating and merging into a single bundle that connects to the microtubule triplet via the D2-rod and the pinhead. Finally, we identified that the cartwheel is indirectly connected to the A-C linker through the triplet base structure extending from the pinhead. Together, our work provides unprecedented evolutionary insights into the architecture of the centriole proximal region, which underlies centriole biogenesis.
Mots clés
in situ
identification
cryo-focused ion beam milling
duplication
9-fold symmetry
basal bodies
bld10/cep135
cartwheel
centriole
chlamydomonas
cryo-electron tomography
in situ
protein
proteomic analysis
sas-6
ultrastructure
in situ Subject Categories Cell Adhesion
Polarity & Cytoskeleton
Structural Biology
Domaines
Sciences du Vivant [q-bio]
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