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PDBsum entry 2q81
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Transcription
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PDB id
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2q81
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References listed in PDB file
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Key reference
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Title
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A beta-Sheet interaction interface directs the tetramerisation of the miz-1 poz domain.
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Authors
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M.A.Stead,
C.H.Trinh,
J.A.Garnett,
S.B.Carr,
A.J.Baron,
T.A.Edwards,
S.C.Wright.
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Ref.
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J Mol Biol, 2007,
373,
820-826.
[DOI no: ]
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PubMed id
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Abstract
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The POZ/BTB domain is an evolutionarily conserved motif found in approximately
40 zinc-finger transcription factors (POZ-ZF factors). Several POZ-ZF factors
are implicated in human cancer, and POZ domain interaction interfaces represent
an attractive target for therapeutic intervention. Miz-1 (Myc-interacting
zinc-finger protein) is a POZ-ZF factor that regulates DNA-damage-induced cell
cycle arrest and plays an important role in human cancer by virtue of its
interaction with the c-Myc and BCL6 oncogene products. The Miz-1 POZ domain
mediates both self-association and the recruitment of non-POZ partners. POZ-ZF
factors generally function as homodimers, although higher-order associations and
heteromeric interactions are known to be physiologically important; crucially,
the interaction interfaces in such large complexes have not been characterised.
We report here the crystal structure of the Miz-1 POZ domain up to 2.1 A
resolution. The tetrameric organisation of Miz-1 POZ reveals two types of
interaction interface between subunits; an interface of alpha-helices resembles
the dimerisation interface of reported POZ domain structures, whereas a novel
beta-sheet interface directs the association of two POZ domain dimers. We show
that the beta-sheet interface directs the tetramerisation of the Miz-1 POZ
domain in solution and therefore represents a newly described candidate
interface for the higher-order homo- and hetero-oligomerisation of POZ-ZF
proteins in vivo.
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Figure 1.
Fig. 1. Structure of the Miz-1 POZ domain. (a) Ribbon
representation of the Miz-1 POZ domain tetramer. Subunits A–D
are indicated in different colours. The secondary structure
elements of the A-chain and of the A:D interface are shown. The
structure of the BCL6 POZ domain (PDB accession code 1r28) is
shown for comparison; the box indicates the β1–β5′
beta-sheet of the BCL6 dimerisation interface that is absent in
Miz-1 (positions on the partner chain of BCL6 are indicated with
primes). The Miz-1 POZ domain (residues 2–115) was expressed
as a glutathione S-transferase fusion protein in E. coli
BL21(DE3)pLysS. The glutathione S-transferase tag was removed by
cleavage with PreScission protease, and the Miz-1 POZ domain
fragment was purified by chromatography on Q-Sepharose, Resource
Q and Supadex 75. Crystals of the purified Miz-1 POZ domain were
obtained by hanging-drop vapour diffusion against 20%
polyethylene glycol 3350; 20% polyethylene glycol 400; 200 mM
MgCl[2]; and 100 mM Hepes (pH 7.5). Details of plasmid
construction, protein purification, X-ray data collection and
structure determination are reported in Supplementary
Data.^[20.]^, ^[21.]^, ^[22.]^, ^[23.]^, ^[24.]^, ^[25.]^,
^[26.]^ and ^[27.] (b) Superposition of POZ domain Cα atoms for
Miz-1, BCL6, PLZF and LRF. Stereoimage of the superpositions of
POZ domain dimers (BCL6, accession code 1r28; PLZF, accession
code 1buo; LRF, accession code 2nn2; the Miz-1 dimer corresponds
to chains A and B). Miz-1 (green), BCL6 (cyan), LRF (magenta),
PLZF (yellow).
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Figure 3.
Fig. 3. Electrostatic surface representation of the Miz-1 POZ
domain. Both flat faces of the Miz-1 POZ tetramer are shown
together with bottom and side surfaces; the bottom surfaces of
the BCL6, PLZF and LRF POZ dimers are shown for comparison.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2007,
373,
820-826)
copyright 2007.
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