6ubn | pdb_00006ubn

Crystal structure of D678E GoxA bound to glycine

spinqualitylabelsall models 6ubn, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6ubn is a 4 chain structure with sequence from Pseudoalteromonas luteoviolacea DSM 6061. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.15Å Ligands: MG, NA, TNQ Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A0A161XU12_9GAMM Publication Abstract from PubMed PlGoxA from Pseudoalteromonas luteoviolacea 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 O2 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 k cat 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. Kinetic and structural evidence that Asp-678 plays multiple roles in catalysis by the quinoprotein glycine oxidase.,Mamounis KJ, Avalos D, Yukl ET, Davidson VL J Biol Chem. 2019 Oct 15. pii: RA119.011255. doi: 10.1074/jbc.RA119.011255. PMID:31615898 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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