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PDBsum entry 1q4q
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Apoptosis inhibitor
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PDB id
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1q4q
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Contents |
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(+ 0 more)
94 a.a.
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101 a.a.
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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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Molecular mechanism of reaper-Grim-Hid-Mediated suppression of diap1-Dependent dronc ubiquitination.
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Authors
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J.Chai,
N.Yan,
J.R.Huh,
J.W.Wu,
W.Li,
B.A.Hay,
Y.Shi.
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Ref.
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Nat Struct Biol, 2003,
10,
892-898.
[DOI no: ]
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PubMed id
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Abstract
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The inhibitor of apoptosis protein DIAP1 inhibits Dronc-dependent cell death by
ubiquitinating Dronc. The pro-death proteins Reaper, Hid and Grim (RHG) promote
apoptosis by antagonizing DIAP1 function. Here we report the structural basis of
Dronc recognition by DIAP1 as well as a novel mechanism by which the RHG
proteins remove DIAP1-mediated downregulation of Dronc. Biochemical and
structural analyses revealed that the second BIR (BIR2) domain of DIAP1
recognizes a 12-residue sequence in Dronc. This recognition is essential for
DIAP1 binding to Dronc, and for targeting Dronc for ubiquitination. Notably, the
Dronc-binding surface on BIR2 coincides with that required for binding to the N
termini of the RHG proteins, which competitively eliminate DIAP1-mediated
ubiquitination of Dronc. These observations reveal the molecular mechanisms of
how DIAP1 recognizes Dronc, and more importantly, how the RHG proteins remove
DIAP1-mediated ubiquitination of Dronc.
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Figure 4.
Figure 4. Dronc and Hid compete with each other for binding to
the same surface groove on the BIR2 domain of DIAP1. (a)
Stereo superposition of the structures of DIAP1-BIR2 bound to
Dronc and to Hid peptide. The Dronc and Hid peptides are green
and orange, respectively. Note the difference in the orientation
of the two peptides. Phe118 of Dronc and Phe4 of Hid occupy the
same general pocket on the surface of DIAP1. (b) A ten-residue
peptide derived from the N terminus of Hid disrupts the
interaction between Dronc and DIAP1. GST-BIR2-Dronc (1 -136)
complex (1.2 mg) was used for each gel filtration run. Hid
peptide (60  g)
was used to disrupt the BIR2 -Dronc complex. The chromatograms
for gel filtration are on the left and the relevant fractions
from gel filtration were visualized by SDS-PAGE and stained with
Coomassie blue.
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Figure 5.
Figure 5. Molecular mechanism of the removal of DIAP1-mediated
Dronc ubiquitination by the pro-apoptosis protein Hid. (a)
The BIR2 domain is required for the ubiquitination of Dronc in
vitro. Various DIAP1 fragments were examined for their E3
ubiquitin ligase activity in the ubiquitination reaction of
Dronc (C318A). The gel was blotted using an anti-Dronc raised
against its CARD domain. E1, E2, Dronc (C318A) and DIAP1 were
individually purified to homogeneity as described in Methods.
(b) A ten-residue peptide derived from the N terminus of Hid
specifically removes DIAP1-mediated ubiquitination of Dronc. The
control peptide has the sequence N-DYPDQNRRRIGAEK-C.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Biol
(2003,
10,
892-898)
copyright 2003.
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