Human Oxygenase Variants Employing a Single Protein FeII Ligand Are Catalytically Active.
Aspartate/asparagine-β-hydroxylase (AspH) is a human 2-oxoglutarate (2OG) and FeII oxygenase that catalyses C3 hydroxylations of aspartate/asparagine residues of epidermal growth factor-like domains (EGFDs). Unusually, AspH employs two histidine residues to chelate FeII rather than the typical triad of two histidine and one glutamate/aspartate residue. We report kinetic, inhibition, and crystallographic studies concerning human AspH variants in which either of its FeII binding histidine residues are substituted for alanine. Both the H725A and, in particular, the H679A AspH variants retain substantial catalytic activity. Crystal structures clearly reveal metal-ligation by only a single protein histidine ligand. The results have implications for the functional assignment of 2OG oxygenases and for the design of non-protein biomimetic catalysts.
['Brasnett|Amelia|A|', 'Pfeffer|Inga|I|0000-0001-5917-2446', 'Brewitz|Lennart|L|0000-0002-9465-777X', 'Chowdhury|Rasheduzzaman|R|', 'Nakashima|Yu|Y|', 'Tumber|Anthony|A|', 'McDonough|Michael A|MA|0000-0003-4664-6942', 'Schofield|Christopher J|CJ|0000-0002-0290-6565']
D001216:Asparagine D001224:Aspartic Acid D055162:Biocatalysis D018360:Crystallography, X-Ray D005296:Ferrous Compounds D006801:Humans D008024:Ligands D006899:Mixed Function Oxygenases D008958:Models, Molecular
aspartate/asparagine-β-hydroxylase 2-oxoglutarate dependent oxygenase biomimetic catalysis facial triad metallo-enzymes