7CCC

The structure of the actin filament uncapping complex mediated by twinfilin

Summary for 7CCC

• Entry DOI: 10.2210/pdb7ccc/pdb
• Descriptor: Actin, alpha skeletal muscle, Twinfilin-1, F-actin-capping protein subunit alpha, ... (7 entities in total)
• Functional Keywords: actin filament regulator, structural protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 5
• Total formula weight: 189146.67

Authors

Robinson, R.C.,Mwangangi, D.M. (deposition date: 2020-06-16, release date: 2021-02-03, Last modification date: 2023-11-29)

Primary citation

Mwangangi, D.M.,Manser, E.,Robinson, R.C.
The structure of the actin filament uncapping complex mediated by twinfilin.
Sci Adv, 7:-, 2021

PubMed Abstract: Uncapping of actin filaments is essential for driving polymerization and depolymerization dynamics from capping protein-associated filaments; however, the mechanisms of uncapping leading to rapid disassembly are unknown. Here, we elucidated the x-ray crystal structure of the actin/twinfilin/capping protein complex to address the mechanisms of twinfilin uncapping of actin filaments. The twinfilin/capping protein complex binds to two G-actin subunits in an orientation that resembles the actin filament barbed end. This suggests an unanticipated mechanism by which twinfilin disrupts the stable capping of actin filaments by inducing a G-actin conformation in the two terminal actin subunits. Furthermore, twinfilin disorders critical actin-capping protein interactions, which will assist in the dissociation of capping protein, and may promote filament uncapping through a second mechanism involving V-1 competition for an actin-binding surface on capping protein. The extensive interactions with capping protein indicate that the evolutionary conserved role of twinfilin is to uncap actin filaments.

PubMed: 33571120
DOI: 10.1126/sciadv.abd5271

Experimental method

X-RAY DIFFRACTION (3.2 Å)