9M5E
Structure of SPIN90 dimer-Arp2/3 complex-nucleated actin filament (singlet complex)
Summary for 9M5E
| Entry DOI | 10.2210/pdb9m5e/pdb |
| EMDB information | 63642 |
| Descriptor | Actin-related protein 3, MAGNESIUM ION, ADENOSINE-5'-DIPHOSPHATE, ... (11 entities in total) |
| Functional Keywords | spin90, actin, cytoskeleton, arp2-3 complex, nucleation promoting factor, cytosolic protein |
| Biological source | Homo sapiens (human) More |
| Total number of polymer chains | 12 |
| Total formula weight | 453886.30 |
| Authors | Francis, J.,Pathri, A.K.,Chowdhury, S. (deposition date: 2025-03-05, release date: 2025-09-10, Last modification date: 2025-11-26) |
| Primary citation | 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 Cited by 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: 40954370DOI: 10.1038/s41594-025-01673-8 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (3.55 Å) |
Structure validation
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