Chloride Supports O2 Activation in the D201G Facial Triad Variant of Factor-Inhibiting Hypoxia Inducible Factor, an ?-Ketoglutarate Dependent Oxygenase.

ABSTRACT: ?-Ketoglutarate (?KG) dependent oxygenases comprise a large superfamily of enzymes that activate O2 for varied reactions. While most of these enzymes contain a nonheme Fe bound by a His2(Asp/Glu) facial triad, a small number of ?KG-dependent halogenases require only the two His ligands to bind Fe and activate O2. The enzyme "factor inhibiting HIF" (FIH) contains a His2Asp facial triad and selectively hydroxylates polypeptides; however, removal of the Asp ligand in the Asp201?Gly variant leads to a highly active enzyme, seemingly without a complete facial triad. Herein, we report on the formation of an Fe-Cl cofactor structure for the Asp201?Gly FIH variant using X-ray absorption spectroscopy (XAS), which provides insight into the structure of the His2Cl facial triad found in halogenases. The Asp201?Gly variant supports anion dependent peptide hydroxylation, demonstrating the requirement for a complete His2X facial triad to support O2 reactivity. Our results indicated that exogenous ligand binding to form a complete His2X facial triad was essential for O2 activation and provides a structural model for the His2Cl-bound nonheme Fe found in halogenases.

SUBMITTER: Chaplin VD 

PROVIDER: S-EPMC6496954 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature