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PDBsum entry 2j4b
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Transcription
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PDB id
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2j4b
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References listed in PDB file
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Key reference
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Title
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Crystal structure, Biochemical and genetic characterization of yeast and e. Cuniculi taf(ii)5 n-Terminal domain: implications for tfiid assembly.
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Authors
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C.Romier,
N.James,
C.Birck,
J.Cavarelli,
C.Vivarès,
M.A.Collart,
D.Moras.
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Ref.
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J Mol Biol, 2007,
368,
1292-1306.
[DOI no: ]
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PubMed id
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Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
percentage match of
96%.
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Abstract
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General transcription factor TFIID plays an essential role in transcription
initiation by RNA polymerase II at numerous promoters. However, understanding of
the assembly and a full structural characterization of this large 15 subunit
complex is lacking. TFIID subunit TAF(II)5 has been shown to be present twice in
this complex and to be critical for the function and assembly of TFIID.
Especially, the TAF(II)5 N-terminal domain is required for its incorporation
within TFIID and immuno-labelling experiments carried out by electron microscopy
at low resolution have suggested that this domain might homodimerize, possibly
explaining the three-lobed architecture of TFIID. However, the resolution at
which the electron microscopy (EM) analyses were conducted is not sufficient to
determine whether homodimerization occurs or whether a more intricate assembly
implying other subunits is required. Here we report the X-ray structures of the
fully evolutionary conserved C-terminal sub-domain of the TAF(II)5 N terminus,
from yeast and the mammalian parasite Encephalitozoon cuniculi. This sub-domain
displays a novel fold with specific surfaces having conserved physico-chemical
properties that can form protein-protein interactions. Although a
crystallographic dimer implying one of these surfaces is present in one of the
crystal forms, several biochemical analyses show that this sub-domain is
monomeric in solution, even at various salt conditions and in presence of
different divalent cations. Consequently, the N-terminal sub-domain of the
TAF(II)5 N terminus, which is homologous to a dimerization motif but has not
been fully conserved during evolution, was studied by analytical
ultracentrifugation and yeast genetics. Our results show that this sub-domain
dimerizes at very high concentration but is neither required for yeast
viability, nor for incorporation of two TAF(II)5 molecules within TFIID and for
the assembly of this complex. Altogether, although our results do not argue in
favour of a homodimerization of the TAF(II)5 N-terminal domain, our structural
analyses suggest a role for this domain in assembly of TFIID and its related
complexes SAGA, STAGA, TFTC and PCAF.
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Figure 1.
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Figure 3.
Figure 3. (a) Electrostatic potential at the surface of S.
cerevisiae T5N2 sub-domain. The orientation is the same as in
Figure 2(c). The electrostatic potentials −8 and +8 k[B]T
(k[B], Boltzmann constant; T, temperature) are coloured red and
blue, respectively. The position of the four-helix bundle/linker
region and triangular structure are indicated by circles. (b)
Homodimer formed through the triangular structure within E.
cuniculi crystals.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2007,
368,
1292-1306)
copyright 2007.
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