6DEC

Crystal structure of Bos taurus Arp2/3 complex binding with C-terminus of Homo sapiens SPIN90

Summary for 6DEC

• Entry DOI: 10.2210/pdb6dec/pdb
• Descriptor: Actin-related protein 3, unidentified, CALCIUM ION, ... (12 entities in total)
• Functional Keywords: spin90 arp2-3 complex, actin filament binding interface, linear filament nucleation activation, endocytosis
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 18
• Total formula weight: 553199.52

Authors

Nolen, B.J.,Luan, Q. (deposition date: 2018-05-11, release date: 2018-10-24, Last modification date: 2023-10-11)

Primary citation

Luan, Q.,Liu, S.L.,Helgeson, L.A.,Nolen, B.J.
Structure of the nucleation-promoting factor SPIN90 bound to the actin filament nucleator Arp2/3 complex.
EMBO J., 37:-, 2018

PubMed Abstract: Unlike the WASP family of Arp2/3 complex activators, WISH/DIP/SPIN90 (WDS) family proteins activate actin filament nucleation by the Arp2/3 complex without the need for a preformed actin filament. This allows WDS proteins to initiate branched actin network assembly by providing seed filaments that activate WASP-bound Arp2/3 complex. Despite their important role in actin network initiation, it is unclear how WDS proteins drive the activating steps that require both WASP and pre-existing actin filaments during WASP-mediated nucleation. Here, we show that SPIN90 folds into an armadillo repeat domain that binds a surface of Arp2/3 complex distinct from the two WASP sites, straddling a hinge point that may stimulate movement of the Arp2 subunit into the activated short-pitch conformation. SPIN90 binds a surface on Arp2/3 complex that overlaps with actin filament binding, explaining how it could stimulate the same structural rearrangements in the complex as pre-existing actin filaments. By revealing how WDS proteins activate the Arp2/3 complex, these data provide a molecular foundation to understand initiation of dendritic actin networks and regulation of Arp2/3 complex by its activators.

PubMed: 30322896
DOI: 10.15252/embj.2018100005

Experimental method

X-RAY DIFFRACTION (4.6 Å)