4Z6Q

Structure of H200N variant of Homoprotocatechuate 2,3-Dioxygenase from B.fuscum in complex with HPCA at 1.57 Ang resolution

4Z6Q の概要

• エントリーDOI: 10.2210/pdb4z6q/pdb
• 関連するPDBエントリー: 4Z6L 4Z6M 4Z6N 4Z6O 4Z6P 4Z6R 4Z6S 4Z6T 4Z6U 4Z6V 4Z6W 4Z6Z
• 分子名称: Homoprotocatechuate 2,3-dioxygenase, FE (II) ION, HEXAETHYLENE GLYCOL, ... (7 entities in total)
• 機能のキーワード: dioxygenase, 2-his-1-carboxylate facial triad, oxygen activation, acid-base catalysis, oxidoreductase
• 由来する生物種: Brevibacterium fuscum
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 169007.42

構造登録者

Kovaleva, E.G.,Lipscomb, J.D. (登録日: 2015-04-06, 公開日: 2015-08-26, 最終更新日: 2023-09-27)

主引用文献

Kovaleva, E.G.,Rogers, M.S.,Lipscomb, J.D.
Structural Basis for Substrate and Oxygen Activation in Homoprotocatechuate 2,3-Dioxygenase: Roles of Conserved Active Site Histidine 200.
Biochemistry, 54:5329-5339, 2015

PubMed Abstract: Kinetic and spectroscopic studies have shown that the conserved active site residue His200 of the extradiol ring-cleaving homoprotocatechuate 2,3-dioxygenase (FeHPCD) from Brevibacterium fuscum is critical for efficient catalysis. The roles played by this residue are probed here by analysis of the steady-state kinetics, pH dependence, and X-ray crystal structures of the FeHPCD position 200 variants His200Asn, His200Gln, and His200Glu alone and in complex with three catecholic substrates (homoprotocatechuate, 4-sulfonylcatechol, and 4-nitrocatechol) possessing substituents with different inductive capacity. Structures determined at 1.35-1.75 Å resolution show that there is essentially no change in overall active site architecture or substrate binding mode for these variants when compared to the structures of the wild-type enzyme and its analogous complexes. This shows that the maximal 50-fold decrease in kcat for ring cleavage, the dramatic changes in pH dependence, and the switch from ring cleavage to ring oxidation of 4-nitrocatechol by the FeHPCD variants can be attributed specifically to the properties of the altered second-sphere residue and the substrate. The results suggest that proton transfer is necessary for catalysis, and that it occurs most efficiently when the substrate provides the proton and His200 serves as a catalyst. However, in the absence of an available substrate proton, a defined proton-transfer pathway in the protein can be utilized. Changes in the steric bulk and charge of the residue at position 200 appear to be capable of altering the rate-limiting step in catalysis and, perhaps, the nature of the reactive species.

PubMed: 26267790
DOI: 10.1021/acs.biochem.5b00709

実験手法

X-RAY DIFFRACTION (1.57 Å)