6ANU

Cryo-EM structure of F-actin complexed with the beta-III-spectrin actin-binding domain

Summary for 6ANU

• Entry DOI: 10.2210/pdb6anu/pdb
• EMDB information: 8886
• Descriptor: Actin, cytoplasmic 1, Spectrin beta chain, non-erythrocytic 2 (2 entities in total)
• Functional Keywords: actin binding protein, filament, structural protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 12
• Total formula weight: 447838.81

Authors

Wang, F.,Orlova, A.,Avery, A.W.,Hays, T.S.,Egelman, E.H. (deposition date: 2017-08-14, release date: 2017-11-22, Last modification date: 2024-03-13)

Primary citation

Avery, A.W.,Fealey, M.E.,Wang, F.,Orlova, A.,Thompson, A.R.,Thomas, D.D.,Hays, T.S.,Egelman, E.H.
Structural basis for high-affinity actin binding revealed by a beta-III-spectrin SCA5 missense mutation.
Nat Commun, 8:1350-1350, 2017

PubMed Abstract: Spinocerebellar ataxia type 5 (SCA5) is a neurodegenerative disease caused by mutations in the cytoskeletal protein β-III-spectrin. Previously, a SCA5 mutation resulting in a leucine-to-proline substitution (L253P) in the actin-binding domain (ABD) was shown to cause a 1000-fold increase in actin-binding affinity. However, the structural basis for this increase is unknown. Here, we report a 6.9 Å cryo-EM structure of F-actin complexed with the L253P ABD. This structure, along with co-sedimentation and pulsed-EPR measurements, demonstrates that high-affinity binding caused by the CH2-localized mutation is due to opening of the two CH domains. This enables CH1 to bind actin aided by an unstructured N-terminal region that becomes α-helical upon binding. This helix is required for association with actin as truncation eliminates binding. Collectively, these results shed light on the mechanism by which β-III-spectrin, and likely similar actin-binding proteins, interact with actin, and how this mechanism can be perturbed to cause disease.

PubMed: 29116080
DOI: 10.1038/s41467-017-01367-w

Experimental method

ELECTRON MICROSCOPY (7 Å)