1C0F

CRYSTAL STRUCTURE OF DICTYOSTELIUM CAATP-ACTIN IN COMPLEX WITH GELSOLIN SEGMENT 1

1C0F の概要

• エントリーDOI: 10.2210/pdb1c0f/pdb
• 関連するPDBエントリー: 1C0G 1DEJ
• 分子名称: GELSOLIN SEGMENT 1, ACTIN, CALCIUM ION, ... (5 entities in total)
• 機能のキーワード: ca actin, contractile protein
• 由来する生物種: Homo sapiens (human); 詳細
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 55789.96

構造登録者

Matsuura, Y.,Stewart, M.,Kawamoto, M.,Kamiya, N.,Saeki, K.,Yasunaga, T.,Wakabayashi, T. (登録日: 1999-07-16, 公開日: 2000-03-01, 最終更新日: 2021-11-03)

主引用文献

Matsuura, Y.,Stewart, M.,Kawamoto, M.,Kamiya, N.,Saeki, K.,Yasunaga, T.,Wakabayashi, T.
Structural basis for the higher Ca(2+)-activation of the regulated actin-activated myosin ATPase observed with Dictyostelium/Tetrahymena actin chimeras
J.Mol.Biol., 296:579-595, 2000

PubMed Abstract: Replacement of residues 228-230 or 228-232 of subdomain 4 in Dictyostelium actin with the corresponding Tetrahymena sequence (QTA to KAY replacement: half chimera-1; QTAAS to KAYKE replacement: full chimera) leads to a higher Ca(2+)-activation of the regulated acto-myosin subfragment-1 ATPase activity. The ratio of ATPase activation in the presence of tropomyosin-troponin and Ca(2+) to that without tropomyosin-troponin becomes about four times as large as the ratio for the wild-type actin. To understand the structural basis of this higher Ca(2+)-activation, we have determined the crystal structures of the 1:1 complex of Dictyostelium mutant actins (half chimera-1 and full chimera) with gelsolin segment-1 to 2.0 A and 2.4 A resolution, respectively, together with the structure of wild-type actin as a control. Although there were local changes on the surface of the subdomain 4 and the phenolic side-chain of Tyr230 displaced the side-chain of Leu236 from a non-polar pocket to a more solvent-accessible position, the structures of the actin chimeras showed that the mutations in the 228-232 region did not introduce large changes in the overall actin structure. This suggests that residues near position 230 formed part of the tropomyosin binding site on actin in actively contracting muscle. The higher Ca(2+)-activation observed with A230Y-containing mutants can be understood in terms of a three-state model for thin filament regulation in which, in the presence of both Ca(2+) and myosin heads, the local changes of actin generated by the mutation (especially its phenolic side-chain) facilitate the transition of thin filaments from a "closed" state to an "open" state. Between 394 and 469 water molecules were identified in the different structures and it was found that actin recognizes hydrated forms of the adenine base and the Ca ion in the nucleotide binding site.

PubMed: 10669610
DOI: 10.1006/jmbi.1999.3467

実験手法

X-RAY DIFFRACTION (2.4 Å)