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PDBsum entry 1h2k
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Transcription activator/inhibitor
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PDB id
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1h2k
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Structure of factor-Inhibiting hypoxia-Inducible factor (hif) reveals mechanism of oxidative modification of hif-1 alpha.
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Authors
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J.M.Elkins,
K.S.Hewitson,
L.A.Mcneill,
J.F.Seibel,
I.Schlemminger,
C.W.Pugh,
P.J.Ratcliffe,
C.J.Schofield.
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Ref.
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J Biol Chem, 2003,
278,
1802-1806.
[DOI no: ]
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PubMed id
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Abstract
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The activity of the transcription factor hypoxia-inducible factor (HIF) is
regulated by oxygen-dependent hydroxylation. Under normoxic conditions,
hydroxylation of proline residues triggers destruction of its alpha-subunit
while hydroxylation of Asn(803) in the C-terminal transactivation domain of
HIF-1 alpha (CAD) prevents its interaction with p300. Here we report crystal
structures of the asparagine hydroxylase (factor-inhibiting HIF, FIH) complexed
with Fe((II)), 2-oxoglutarate cosubstrate, and CAD fragments, which reveal the
structural basis of HIF modification. CAD binding to FIH occurs via an induced
fit process at two distinct interaction sites. At the hydroxylation site CAD
adopts a loop conformation, contrasting with a helical conformation for the same
residues when bound to p300. Asn(803) of CAD is buried and precisely orientated
in the active site such that hydroxylation occurs at its beta-carbon. Together
with structures with the inhibitors Zn((II)) and N-oxaloylglycine, analysis of
the FIH-CAD complexes will assist design of hydroxylase inhibitors with
proangiogenic properties. Conserved structural motifs within FIH imply it is one
of an extended family of Fe((II)) oxygenases involved in gene regulation.
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Figure 1.
Fig. 1. The FIH-CAD complex (a-c, structure 1; d,
structure 2). a, FIH monomer. The CAD peptide is shown as a
ball-and-stick representation in red and the DSBH motif in
green. b, FIH dimer. The two molecules of FIH are in dark and
light blue, the DSBH motif is in green, and the CAD peptide is
in red. c, the 2OG binding site with bound NOG is shown in
yellow. The Fe^(II) is colored pink, and the 2mF[o]  DF[c]
electron density map is contoured at 1.5  . d,
orientation of CAD Asn803 at the FIH active site. The 2OG and
CAD peptide are shown in yellow.
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Figure 2.
Fig. 2. FIH-CAD interactions. a, CAD fragments are shown
as stick models in yellow above a van der Waals surface of FIH.
FIH residues beneath the surface are colored green. Dotted red
lines represent electrostatic bonds. b, alternative view of site
1. Note Asn803 is deeply buried. c, electron density for the
bound CAD peptide (structure 1). CAD residues 795-806 (site 1,
left) and 812-823 (site 2, right) are shown as ball-and-stick
representations in yellow. The difference electron density,
contoured at 2.2 (left) and
1.5 (right),
was calculated after random model perturbation and refinement
with CAD omitted to remove model bias.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2003,
278,
1802-1806)
copyright 2003.
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