9DUV

Cryo-EM structure of recombinant R254H ACTA1 phalloidin-stabilized F-actin

9DUV の概要

• エントリーDOI: 10.2210/pdb9duv/pdb
• 関連するPDBエントリー: 9DUU
• EMDBエントリー: 47179 47180
• 分子名称: Actin, alpha skeletal muscle, phalloidin, ADENOSINE-5'-DIPHOSPHATE, ... (4 entities in total)
• 機能のキーワード: actin, cardiomyopathy, contractility, muscle, sarcomere, structural protein
• 由来する生物種: Homo sapiens (human); 詳細
• タンパク質・核酸の鎖数: 13
• 化学式量合計: 259510.82

構造登録者

Garg, A.,Greenberg, M.J.,Zhang, R. (登録日: 2024-10-04, 公開日: 2024-10-23, 最終更新日: 2024-12-11)

主引用文献

Garg, A.,Jansen, S.,Greenberg, L.,Zhang, R.,Lavine, K.J.,Greenberg, M.J.
Dilated cardiomyopathy-associated skeletal muscle actin (ACTA1) mutation R256H disrupts actin structure and function and causes cardiomyocyte hypocontractility.
Proc.Natl.Acad.Sci.USA, 121:e2405020121-e2405020121, 2024

PubMed Abstract: Skeletal muscle actin (ACTA1) mutations are a prevalent cause of skeletal myopathies consistent with ACTA1's high expression in skeletal muscle. Rare de novo mutations in ACTA1 associated with combined cardiac and skeletal myopathies have been reported, but ACTA1 represents only ~20% of the total actin pool in cardiomyocytes, making its role in cardiomyopathy controversial. Here we demonstrate how a mutation in an actin isoform expressed at low levels in cardiomyocytes can cause cardiomyopathy by focusing on a unique ACTA1 variant, R256H. We previously identified this variant in a family with dilated cardiomyopathy, who had reduced systolic function without clinical skeletal myopathy. Using a battery of multiscale biophysical tools, we show that R256H has potent effects on ACTA1 function at the molecular scale and in human cardiomyocytes. Importantly, we demonstrate that R256H acts in a dominant manner, where the incorporation of small amounts of mutant protein into thin filaments is sufficient to disrupt molecular contractility, and that this effect is dependent on the presence of troponin and tropomyosin. To understand the structural basis of this change in regulation, we resolved a structure of R256H filaments using cryoelectron microscopy, and we see alterations in actin's structure that have the potential to disrupt interactions with tropomyosin. Finally, we show that human-induced pluripotent stem cell cardiomyocytes demonstrate reduced contractility and sarcomeric organization. Taken together, we demonstrate that R256H has multiple effects on ACTA1 function that are sufficient to cause reduced contractility and establish a likely causative relationship between ACTA1 R256H and clinical cardiomyopathy.

PubMed: 39503885
DOI: 10.1073/pnas.2405020121

実験手法

ELECTRON MICROSCOPY (3.3 Å)