6f33
From Proteopedia
Crystal structure of ectonucleotide phosphodiesterase/pyrophosphatase-3 (NPP3) in complex with AMPNPP
Structural highlights
FunctionENPP3_RAT Hydrolase that metabolizes extracellular nucleotides, including ATP, GTP, UTP and CTP (By similarity). Limits mast cell and basophil responses during inflammation and during the chronic phases of allergic responses by eliminating the extracellular ATP that functions as signaling molecule and activates basophils and mast cells and induces the release of inflammatory cytokines. Metabolizes extracellular ATP in the lumen of the small intestine, and thereby prevents ATP-induced apoptosis of intestinal plasmacytoid dendritic cells (By similarity). Has also alkaline phosphodiesterase activity (PubMed:9096610).[UniProtKB:O14638][UniProtKB:Q6DYE8][1] Publication Abstract from PubMedEctonucleotide phosphodiesterase/pyrophosphatase-3 (NPP3) is a membrane-bound glycoprotein that regulates extracellular levels of nucleotides. NPP3 is known to contribute to the immune response on basophils by hydrolyzing ATP and to regulate the glycosyltransferase activity in Neuro2a cells. Here, we report on crystal structures of the nuclease and phosphodiesterase domains of rat NPP3 in complex with different substrates, products and substrate analogs giving insight into details of the catalytic mechanism. Complex structures with a phosphate ion, the product AMP and the substrate analog AMPNPP provide a consistent picture of the coordination of the substrate in which one zinc ion activates the threonine nucleophile whereas the other zinc ion binds the phosphate group. Co-crystal structures with the dinucleotide substrates Ap4A and UDPGlcNAc reveal a binding pocket for the larger leaving groups of these substrates. The crystal structures as well as mutational and kinetic analysis demonstrate that the larger leaving groups interact only weakly with the enzyme such that the substrate affinity is dominated by the interactions of the first nucleoside group. For this moiety, the nucleobase is stacked between Y290 and F207 and polar interactions with the protein are only formed via water molecules thus explaining the limited nucleobase selectivity. Crystal structure and substrate binding mode of ectonucleotide phosphodiesterase/pyrophosphatase-3 (NPP3).,Dohler C, Zebisch M, Strater N Sci Rep. 2018 Jul 18;8(1):10874. doi: 10.1038/s41598-018-28814-y. PMID:30022031[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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