期刊
NATURE COMMUNICATIONS
卷 13, 期 1, 页码 -出版社
NATURE PORTFOLIO
DOI: 10.1038/s41467-022-28079-0
关键词
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资金
- Ministry of Science, Research and the Arts Baden-Wurttemberg
- German Research Foundation [INST 35/1314-1 FUGG, INST 35/1134-1 FUGG, DFG Schi 295/4-4, DFG PF 963/1-4]
- Dirk Flemming (BZH, Heidelberg)
- Gotz Hofhaus (BioQuant, Heidelberg)
The study reveals the assembly mechanism of γ-TuRC and the functional role of actin in microtubule nucleation.
The gamma-tubulin ring complex (gamma-TuRC) is the principal microtubule nucleation template in vertebrates. Recent cryo-EM reconstructions visualized the intricate quaternary structure of the gamma-TuRC, containing more than thirty subunits, raising fundamental questions about gamma-TuRC assembly and the role of actin as an integral part of the complex. Here, we reveal the structural mechanism underlying modular gamma-TuRC assembly and identify a functional role of actin in microtubule nucleation. During gamma-TuRC assembly, a GCP6-stabilized core comprising GCP2-3-4-5-4-6 is expanded by stepwise recruitment, selective stabilization and conformational locking of four pre-formed GCP2-GCP3 units. Formation of the lumenal bridge specifies incorporation of the terminal GCP2-GCP3 unit and thereby leads to closure of the gamma-TuRC ring in a left-handed spiral configuration. Actin incorporation into the complex is not relevant for gamma-TuRC assembly and structural integrity, but determines gamma-TuRC geometry and is required for efficient microtubule nucleation and mitotic chromosome alignment in vivo. The human microtubule nucleator gamma-TuRC is composed of more than thirty subunits, including actin. Here the authors reveal the structural mechanism of modular gamma-TuRC assembly and show a functional role of actin in microtubule nucleation.
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