2DGM

Crystal structure of Escherichia coli GadB in complex with iodide

2DGM の概要

• エントリーDOI: 10.2210/pdb2dgm/pdb
• 関連するPDBエントリー: 1PMM 1PMO 2DGK 2DGL
• 分子名称: Glutamate decarboxylase beta, IODIDE ION, PYRIDOXAL-5'-PHOSPHATE, ... (7 entities in total)
• 機能のキーワード: gadb complexed with iodide, lyase
• 由来する生物種: Escherichia coli
• 細胞内の位置: Cytoplasm: P69910
• タンパク質・核酸の鎖数: 6
• 化学式量合計: 322676.02

構造登録者

Gruetter, M.G.,Capitani, G.,Gut, H. (登録日: 2006-03-14, 公開日: 2006-06-20, 最終更新日: 2023-10-25)

主引用文献

Gut, H.,Pennacchietti, E.,John, R.A.,Bossa, F.,Capitani, G.,De Biase, D.,Gruetter, M.G.
Escherichia coli acid resistance: pH-sensing, activation by chloride and autoinhibition in GadB
Embo J., 25:2643-2651, 2006

PubMed Abstract: Escherichia coli and other enterobacteria exploit the H+ -consuming reaction catalysed by glutamate decarboxylase to survive the stomach acidity before reaching the intestine. Here we show that chloride, extremely abundant in gastric secretions, is an allosteric activator producing a 10-fold increase in the decarboxylase activity at pH 5.6. Cooperativity and sensitivity to chloride were lost when the N-terminal 14 residues, involved in the formation of two triple-helix bundles, were deleted by mutagenesis. X-ray structures, obtained in the presence of the substrate analogue acetate, identified halide-binding sites at the base of each N-terminal helix, showed how halide binding is responsible for bundle stability and demonstrated that the interconversion between active and inactive forms of the enzyme is a stepwise process. We also discovered an entirely novel structure of the cofactor pyridoxal 5'-phosphate (aldamine) to be responsible for the reversibly inactivated enzyme. Our results link the entry of chloride ions, via the H+/Cl- exchange activities of ClC-ec1, to the trigger of the acid stress response in the cell when the intracellular proton concentration has not yet reached fatal values.

PubMed: 16675957
DOI: 10.1038/sj.emboj.7601107

実験手法

X-RAY DIFFRACTION (1.95 Å)