4uwd
From Proteopedia
HIF prolyl hydroxylase 2 (PHD2/ EGLN1) D315E VARIANT in complex with Mn(II) and N-[(1-chloro-4-hydroxyisoquinolin-3-yl)carbonyl]glycine (IOX3/UN9)
Structural highlights
DiseaseEGLN1_HUMAN Defects in EGLN1 are the cause of familial erythrocytosis type 3 (ECYT3) [MIM:609820. ECYT3 is an autosomal dominant disorder characterized by increased serum red blood cell mass, elevated serum hemoglobin and hematocrit, and normal serum erythropoietin levels.[1] [2] FunctionEGLN1_HUMAN Cellular oxygen sensor that catalyzes, under normoxic conditions, the post-translational formation of 4-hydroxyproline in hypoxia-inducible factor (HIF) alpha proteins. Hydroxylates a specific proline found in each of the oxygen-dependent degradation (ODD) domains (N-terminal, NODD, and C-terminal, CODD) of HIF1A. Also hydroxylates HIF2A. Has a preference for the CODD site for both HIF1A and HIF1B. Hydroxylated HIFs are then targeted for proteasomal degradation via the von Hippel-Lindau ubiquitination complex. Under hypoxic conditions, the hydroxylation reaction is attenuated allowing HIFs to escape degradation resulting in their translocation to the nucleus, heterodimerization with HIF1B, and increased expression of hypoxy-inducible genes. EGLN1 is the most important isozyme under normoxia and, through regulating the stability of HIF1, involved in various hypoxia-influenced processes such as angiogenesis in retinal and cardiac functionality.[3] [4] [5] [6] [7] Publication Abstract from PubMedProlyl hydroxylase domain 2 (PHD2) catalyses the post-translational hydroxylation of the Hypoxia Inducible Factor (HIF), a modification that regulates the hypoxic response in humans. PHD2 is an FeII/2-oxoglutarate (2OG) oxygenase; its catalysis is proposed to provide a link between cellular HIF levels and changes in O2 availability. Transient kinetic studies have shown that PHD2 reacts slowly with O2 compared to some other studied 2OG oxygenases, a property which may be related to its hypoxia sensing role. PHD2 forms a stable complex with FeII and 2OG; crystallographic and kinetic analyses indicate that an FeII-coordinated water molecule, which must be displaced prior to O2 binding, is relatively stable in the active site of PHD2. We used active site substitutions to investigate whether these properties are related to the slow reaction of PHD2 with O2. Whilst disruption of 2OG binding in a R383K variant did not accelerate O2 activation, we found that substitution of the FeII binding Asp with Glu (D315E) manifested significantly reduced FeII binding yet maintained catalytic activity with a 5-fold faster reaction with O2. The results inform on how the precise active site environment of oxygenases can affect rates of O2 activation and provide insights into limiting steps in PHD catalysis. Investigating the contribution of the active site environment to the slow reaction of hypoxia-inducible factor prolyl hydroxylase domain 2 with oxygen.,Tarhonskaya H, Chowdhury R, Leung IK, Loik ND, McCullagh JS, Claridge TD, Schofield CJ, Flashman E Biochem J. 2014 Aug 14. PMID:25120187[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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