Structural basis for high-affinity actin binding revealed by a β-III-spectrin SCA5 missense mutation

Adam W. Avery, Michael E. Fealey, Fengbin Wang, Albina Orlova, Andrew R Thompson, David D Thomas, Tom S Hays, Edward H. Egelman

Research output: Contribution to journalArticle

3 Citations (Scopus)

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.

Original languageEnglish (US)
Article number1350
JournalNature communications
Volume8
Issue number1
DOIs
StatePublished - Dec 1 2017

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ataxia
Spinocerebellar Ataxias
Spectrin
Missense Mutation
mutations
affinity
Actins
Mutation
Neurodegenerative diseases
proteins
Microfilament Proteins
leucine
Cytoskeletal Proteins
causes
Sedimentation
Proline
Leucine
Neurodegenerative Diseases
helices
Paramagnetic resonance

Cite this

Structural basis for high-affinity actin binding revealed by a β-III-spectrin SCA5 missense mutation. / Avery, Adam W.; Fealey, Michael E.; Wang, Fengbin; Orlova, Albina; Thompson, Andrew R; Thomas, David D; Hays, Tom S; Egelman, Edward H.

In: Nature communications, Vol. 8, No. 1, 1350, 01.12.2017.

Research output: Contribution to journalArticle

Avery, Adam W. ; Fealey, Michael E. ; Wang, Fengbin ; Orlova, Albina ; Thompson, Andrew R ; Thomas, David D ; Hays, Tom S ; Egelman, Edward H. / Structural basis for high-affinity actin binding revealed by a β-III-spectrin SCA5 missense mutation. In: Nature communications. 2017 ; Vol. 8, No. 1.
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AU - Thomas, David D

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