| Structural highlights
Disease
[EGLN1_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]
Function
[EGLN1_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 PubMed
Prolyl 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.
References
- ↑ Percy MJ, Zhao Q, Flores A, Harrison C, Lappin TR, Maxwell PH, McMullin MF, Lee FS. A family with erythrocytosis establishes a role for prolyl hydroxylase domain protein 2 in oxygen homeostasis. Proc Natl Acad Sci U S A. 2006 Jan 17;103(3):654-9. Epub 2006 Jan 9. PMID:16407130 doi:0508423103
- ↑ Percy MJ, Furlow PW, Beer PA, Lappin TR, McMullin MF, Lee FS. A novel erythrocytosis-associated PHD2 mutation suggests the location of a HIF binding groove. Blood. 2007 Sep 15;110(6):2193-6. Epub 2007 Jun 19. PMID:17579185 doi:10.1182/blood-2007-04-084434
- ↑ Epstein AC, Gleadle JM, McNeill LA, Hewitson KS, O'Rourke J, Mole DR, Mukherji M, Metzen E, Wilson MI, Dhanda A, Tian YM, Masson N, Hamilton DL, Jaakkola P, Barstead R, Hodgkin J, Maxwell PH, Pugh CW, Schofield CJ, Ratcliffe PJ. C. elegans EGL-9 and mammalian homologs define a family of dioxygenases that regulate HIF by prolyl hydroxylation. Cell. 2001 Oct 5;107(1):43-54. PMID:11595184
- ↑ Ivan M, Haberberger T, Gervasi DC, Michelson KS, Gunzler V, Kondo K, Yang H, Sorokina I, Conaway RC, Conaway JW, Kaelin WG Jr. Biochemical purification and pharmacological inhibition of a mammalian prolyl hydroxylase acting on hypoxia-inducible factor. Proc Natl Acad Sci U S A. 2002 Oct 15;99(21):13459-64. Epub 2002 Sep 26. PMID:12351678 doi:10.1073/pnas.192342099
- ↑ Ozer A, Wu LC, Bruick RK. The candidate tumor suppressor ING4 represses activation of the hypoxia inducible factor (HIF). Proc Natl Acad Sci U S A. 2005 May 24;102(21):7481-6. Epub 2005 May 16. PMID:15897452 doi:0502716102
- ↑ Yasumoto K, Kowata Y, Yoshida A, Torii S, Sogawa K. Role of the intracellular localization of HIF-prolyl hydroxylases. Biochim Biophys Acta. 2009 May;1793(5):792-7. doi: 10.1016/j.bbamcr.2009.01.014. , Epub 2009 Feb 5. PMID:19339211 doi:10.1016/j.bbamcr.2009.01.014
- ↑ Su Y, Loos M, Giese N, Metzen E, Buchler MW, Friess H, Kornberg A, Buchler P. Prolyl hydroxylase-2 (PHD2) exerts tumor-suppressive activity in pancreatic cancer. Cancer. 2012 Feb 15;118(4):960-72. doi: 10.1002/cncr.26344. Epub 2011 Jul 26. PMID:21792862 doi:10.1002/cncr.26344
- ↑ Tarhonskaya H, Chowdhury R, Leung IK, Loik ND, McCullagh JS, Claridge TD, Schofield CJ, Flashman E. Investigating the contribution of the active site environment to the slow reaction of hypoxia-inducible factor prolyl hydroxylase domain 2 with oxygen. Biochem J. 2014 Aug 14. PMID:25120187 doi:http://dx.doi.org/10.1042/BJ20140779
|
