Liu, Tianyang and Cao, L. and Mladenov, M. and Romet-Lemonne, G. and Way, M. and Moores, Carolyn A. (2025) Arp2/3-mediated bidirectional actin assembly by SPIN90 dimers. Nature Structure and Molecular Biology , ISSN 1545-9993.
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Abstract
Branched actin networks nucleated by the Arp2/3 complex play critical roles in various cellular processes, from cell migration to intracellular transport. However, when activated by WISH/DIP/SPIN90 family proteins, Arp2/3 nucleates linear actin filaments. We found that human SPIN90 is a dimer that can nucleate bidirectional actin filaments. To understand the basis for this, we determined a 3 Å resolution structure of human SPIN90-Arp2/3 complex nucleating actin filaments. Our structure shows that SPIN90 dimerises via a 3-helix bundle and interacts with two Arp2/3 complexes. Each SPIN90 molecule binds both Arp2/3 complexes to promote their activation. Our analysis demonstrates that single filament nucleation by Arp2/3 is mechanistically more like branch formation than previously appreciated. The dimerisation domain in SPIN90 orthologues is conserved in metazoans, suggesting that this mode of bidirectional nucleation is a common strategy to generate anti-parallel actin filaments.
Metadata
| Item Type: | Article |
|---|---|
| School: | Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences |
| Depositing User: | Administrator |
| Date Deposited: | 15 Sep 2025 13:30 |
| Last Modified: | 19 Sep 2025 04:26 |
| URI: | https://eprints.bbk.ac.uk/id/eprint/56075 |
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