6UBR

Crystal structure of D678A GoxA bound to glycine at pH 7.5

6UBR の概要

• エントリーDOI: 10.2210/pdb6ubr/pdb
• 分子名称: Uncharacterized protein, MAGNESIUM ION, SULFATE ION, ... (6 entities in total)
• 機能のキーワード: tryotiophylquinone, oxidase, oxidoreductase
• 由来する生物種: Pseudoalteromonas luteoviolacea DSM 6061
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 366626.86

構造登録者

Yukl, E.T.,Avalos, D. (登録日: 2019-09-12, 公開日: 2019-10-23, 最終更新日: 2023-10-11)

主引用文献

Mamounis, K.J.,Avalos, D.,Yukl, E.T.,Davidson, V.L.
Kinetic and structural evidence that Asp-678 plays multiple roles in catalysis by the quinoprotein glycine oxidase.
J.Biol.Chem., 294:17463-17470, 2019

PubMed Abstract: PlGoxA from is a glycine oxidase that utilizes a protein-derived cysteine tryptophylquinone (CTQ) cofactor. A notable feature of its catalytic mechanism is that it forms a stable product-reduced CTQ adduct that is not hydrolyzed in the absence of O Asp-678 resides near the quinone moiety of PlGoxA, and an Asp is structurally conserved in this position in all tryptophylquinone enzymes. In those other enzymes, mutation of that Asp results in no or negligible CTQ formation. In this study, mutation of Asp-678 in PlGoxA did not abolish CTQ formation. This allowed, for the first time, studying the role of this residue in catalysis. D678A and D678N substitutions yielded enzyme variants with CTQ, which did not react with glycine, although glycine was present in the crystal structures in the active site. D678E PlGoxA was active but exhibited a much slower This mutation altered the kinetic mechanism of the reductive half-reaction such that one could observe a previously undetected reactive intermediate, an initial substrate-oxidized CTQ adduct, which converted to the product-reduced CTQ adduct. These results indicate that Asp-678 is involved in the initial deprotonation of the amino group of glycine, enabling nucleophilic attack of CTQ, as well as the deprotonation of the substrate-oxidized CTQ adduct, which is coupled to CTQ reduction. The structures also suggest that Asp-678 is acting as a proton relay that directs these protons to a water channel that connects the active sites on the subunits of this homotetrameric enzyme.

PubMed: 31615898
DOI: 10.1074/jbc.RA119.011255

実験手法

X-RAY DIFFRACTION (1.96 Å)