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Elife. 2019 Feb 11;8. pii: e43434. doi: 10.7554/eLife.43434.

Electron cryo-tomography provides insight into procentriole architecture and assembly mechanism.

Author information

1
Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.
2
Centro Nacional de Biotecnologia (CSIC), Madrid, Spain.
3
Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States.

Abstract

Centriole is an essential structure with multiple functions in cellular processes. Centriole biogenesis and homeostasis is tightly regulated. Using electron cryo-tomography (cryoET) we present the structure of procentrioles from Chlamydomonas reinhardtii. We identified a set of non-tubulin components attached to the triplet microtubule (MT), many are at the junctions of tubules likely to reinforce the triplet. We describe structure of the A-C linker that bridges neighboring triplets. The structure infers that POC1 is likely an integral component of A-C linker. Its conserved WD40 β-propeller domain provides attachment sites for other A-C linker components. The twist of A-C linker results in an iris diaphragm-like motion of the triplets in the longitudinal direction of procentriole. Finally, we identified two assembly intermediates at the growing ends of procentriole allowing us to propose a model for the procentriole assembly. Our results provide a comprehensive structural framework for understanding the molecular mechanisms underpinning procentriole biogenesis and assembly.

KEYWORDS:

cell biology; centriole; chlamydomonas reinhardtii; electron cryo-tomography; microtubule triplet; procentriole; structure heterogeneity; subtomogram averaging

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