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

被引：38

作者：

Avery, Adam W. ^{[1
]}

Fealey, Michael E. ^{[2
]}

Wang, Fengbin ^{[3
]}

Orlova, Albina ^{[3
]}

Thompson, Andrew R. ^{[2
]}

Thomas, David D. ^{[2
]}

Hays, Thomas S. ^{[1
]}

Egelman, Edward H. ^{[3
]}

机构：

[1] Univ Minnesota, Dept Genet Cell Biol & Dev, Minneapolis, MN 55455 USA

[2] Univ Minnesota, Dept Biochem Mol Biol & Biophys, Minneapolis, MN 55455 USA

[3] Univ Virginia, Dept Biochem & Mol Genet, Charlottesville, VA 22908 USA

来源：

NATURE COMMUNICATIONS | 2017年 / 8卷

关键词：

ATAXIA TYPE 5; CALPONIN HOMOLOGY DOMAINS; CRYO-EM STRUCTURE; F-ACTIN; CRYSTAL-STRUCTURE; ALPHA-ACTININ; UTROPHIN; PROTEIN; VISUALIZATION; ORGANIZATION;

D O I：

10.1038/s41467-017-01367-w

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

Spinocerebellar ataxia type 5 (SCA5) is a neurodegenerative disease caused by mutations in the cytoskeletal protein beta-III-spectrin. Previously, a SCA5 mutation resulting in a leucine-toproline 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 angstrom 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 alpha-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 beta-III-spectrin, and likely similar actin-binding proteins, interact with actin, and how this mechanism can be perturbed to cause disease.

引用

页数：7