9SMX

CM1-activated gTuRC in complex with nascent alpha-E254D mutant microtubules

This is a non-PDB format compatible entry.

Summary for 9SMX

• Entry DOI: 10.2210/pdb9smx/pdb
• EMDB information: 55043
• Descriptor: Gamma-tubulin complex component 3, Gamma-tubulin complex component 4, Gamma-tubulin complex component 5, ... (13 entities in total)
• Functional Keywords: microtubule, cytoskeleton, g-tubulin ring complex, tubulin, structural protein, cdk5rap2, cm1, nucleation
• Biological source: Saccharomyces cerevisiae S288C; More
• Total number of polymer chains: 73
• Total formula weight: 4442407.31

Authors

Llorca, O.,Serna, M.,Lopez-Perrote, A. (deposition date: 2025-09-09, release date: 2026-05-13)

Primary citation

Serna, M.,Brito, C.,Speroni, S.,Zimmermann, F.,Lopez-Perrote, A.,Gili, M.,Lacasa, C.,Luders, J.,Surrey, T.,Llorca, O.
Structural basis of human gamma TuRC closure during CM1-activated microtubule nucleation.
Nat Commun, 2026

PubMed Abstract: Microtubule nucleation by the γ-tubulin ring complex (γTuRC) is spatiotemporally regulated and in higher eukaryotes is thought to involve a transition from an inactive open to an active closed conformation that matches the microtubule geometry. However, γTuRC activators only promote a partially closed conformation, raising the question of whether complete closure is required for activation. Combining in vitro nucleation assays and cryo-EM, we find that centrosomin motif 1 (CM1), a conserved element of several γTuRC regulators, potently accelerates human γTuRC-mediated microtubule nucleation by facilitating complete closure of γTuRC as the nascent microtubule assembles. A 3.7 Å cryo-EM structure identifies the γTuRC latch and several interactions involved in conformational closure. Notably, the distinct subunits that keep γTuRC open and inactive in higher eukaryotes also participate in its closure and activation. This work provides additional insight into the logic of the human γTuRC architecture and its activation by CM1.

PubMed: 41888131
DOI: 10.1038/s41467-026-70773-w

Experimental method

ELECTRON MICROSCOPY (3.67 Å)