3BRX

Crystal Structure of calcium-bound cotton annexin Gh1

3BRX の概要

• エントリーDOI: 10.2210/pdb3brx/pdb
• 関連するPDBエントリー: 1N00
• 分子名称: Annexin, PHOSPHATE ION, CALCIUM ION, ... (4 entities in total)
• 機能のキーワード: calcium binding, membrane binding, annexin, membrane protein
• 由来する生物種: Gossypium hirsutum (upland cotton)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 36750.03

構造登録者

Hu, N.-J.,Hofmann, A. (登録日: 2007-12-21, 公開日: 2008-05-06, 最終更新日: 2024-03-13)

主引用文献

Hu, N.-J.,Yusof, A.M.,Winter, A.,Osman, A.,Reeve, A.K.,Hofmann, A.
The crystal structure of calcium-bound annexin Gh1 from Gossypium hirsutum and its implications for membrane binding mechanisms of plant annexins.
J.Biol.Chem., 283:18314-18322, 2008

PubMed Abstract: Plant annexins show distinct differences in comparison with their animal orthologues. In particular, the endonexin sequence, which is responsible for coordination of calcium ions in type II binding sites, is only partially conserved in plant annexins. The crystal structure of calcium-bound cotton annexin Gh1 was solved at 2.5 A resolution and shows three metal ions coordinated in the first and fourth repeat in types II and III binding sites. Although the protein has no detectable affinity for calcium in solution, in the presence of phospholipid vesicles, we determined a stoichiometry of four calcium ions per protein molecule using isothermal titration calorimetry. Further analysis of the crystal structure showed that binding of a fourth calcium ion is structurally possible in the DE loop of the first repeat. Data from this study are in agreement with the canonical membrane binding of annexins, which is facilitated by the convex surface associating with the phospholipid bilayer by a calcium bridging mechanism. In annexin Gh1, this membrane-binding state is characterized by four calcium bridges in the I/IV module of the protein and by direct interactions of several surface-exposed basic and hydrophobic residues with the phospholipid membrane. Analysis of the protein fold stability revealed that the presence of calcium lowers the thermal stability of plant annexins. Furthermore, an additional unfolding step was detected at lower temperatures, which can be explained by the anchoring of the N-terminal domain to the C-terminal core by two conserved hydrogen bonds.

PubMed: 18441010
DOI: 10.1074/jbc.M801051200

実験手法

X-RAY DIFFRACTION (2.5 Å)