9M5E

Structure of SPIN90 dimer-Arp2/3 complex-nucleated actin filament (singlet complex)

9M5E の概要

• エントリーDOI: 10.2210/pdb9m5e/pdb
• EMDBエントリー: 63642
• 分子名称: Actin-related protein 3, MAGNESIUM ION, ADENOSINE-5'-DIPHOSPHATE, ... (11 entities in total)
• 機能のキーワード: spin90, actin, cytoskeleton, arp2-3 complex, nucleation promoting factor, cytosolic protein
• 由来する生物種: Homo sapiens (human); 詳細
• タンパク質・核酸の鎖数: 12
• 化学式量合計: 453886.30

構造登録者

Francis, J.,Pathri, A.K.,Chowdhury, S. (登録日: 2025-03-05, 公開日: 2025-09-10, 最終更新日: 2025-11-26)

主引用文献

Francis, J.,Pathri, A.K.,Shyam, K.T.,Sripada, S.,Mitra, R.,Narvaez-Ortiz, H.Y.,Eliyan, K.V.,Nolen, B.J.,Chowdhury, S.
Activation of Arp2/3 complex by a SPIN90 dimer in linear actin-filament nucleation.
Nat.Struct.Mol.Biol., 32:2272-2284, 2025

PubMed Abstract: Arp2/3 complex is a key nucleator of actin filaments. It requires activation by nucleation-promoting factors (NPFs). WISH/DIP1/SPIN90 (WDS) proteins represent a unique class of NPFs that activate the Arp2/3 complex independently of preexisting filaments, promoting linear actin-filament nucleation. In fission yeast, Dip1 binds to the clamp subunits in Arp2/3 complex to induce the short-pitch conformation, where Arp2 moves closer to Arp3 to mimic a filamentous actin dimer. However, how WDS proteins stimulate subunit flattening in Arp subunits, a 'scissor-like' conformational change akin to what is observed in an actin monomer during filament formation, remained unclear. Here we present cryo-electron microscopy structures of human SPIN90 bound to activated bovine Arp2/3 complex on an actin filament pointed end. The structures show that SPIN90 dimerizes through a metazoan-specific domain in the middle segment, engaging both the clamp and the Arp3/ARPC3 interface, to drive the activating conformational changes in Arp2/3 complex. Remarkably, a single SPIN90 dimer can also bridge two Arp2/3 complexes, enabling bidirectional actin nucleation and suggesting a mechanism for rapidly assembling complex actin network architectures.

PubMed: 40954370
DOI: 10.1038/s41594-025-01673-8

実験手法

ELECTRON MICROSCOPY (3.55 Å)