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Publication Abstract from PubMed

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.

Modular assembly of the principal microtubule nucleator gamma-TuRC.,Wurtz M, Zupa E, Atorino ES, Neuner A, Bohler A, Rahadian AS, Vermeulen BJA, Tonon G, Eustermann S, Schiebel E, Pfeffer S Nat Commun. 2022 Jan 25;13(1):473. doi: 10.1038/s41467-022-28079-0. PMID:35078983^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.