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PDBsum entry 1b22
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DNA binding protein
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PDB id
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1b22
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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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The n-Terminal domain of the human rad51 protein binds DNA: structure and a DNA binding surface as revealed by nmr.
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Authors
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H.Aihara,
Y.Ito,
H.Kurumizaka,
S.Yokoyama,
T.Shibata.
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Ref.
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J Mol Biol, 1999,
290,
495-504.
[DOI no: ]
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PubMed id
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Abstract
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Human Rad51 protein (HsRad51) is a homolog of Escherichia coli RecA protein, and
functions in DNA repair and recombination. In higher eukaryotes, Rad51 protein
is essential for cell viability. The N-terminal region of HsRad51 is highly
conserved among eukaryotic Rad51 proteins but is absent from RecA, suggesting a
Rad51-specific function for this region. Here, we have determined the structure
of the N-terminal part of HsRad51 by NMR spectroscopy. The N-terminal region
forms a compact domain consisting of five short helices, which shares structural
similarity with a domain of endonuclease III, a DNA repair enzyme of E. coli.
NMR experiments did not support the involvement of the N-terminal domain in
HsRad51-HsBrca2 interaction or the self-association of HsRad51 as proposed by
previous studies. However, NMR tiration experiments demonstrated a physical
interaction of the domain with DNA, and allowed mapping of the DNA binding
surface. Mutation analysis showed that the DNA binding surface is essential for
double-stranded and single-stranded DNA binding of HsRad51. Our results suggest
the presence of a DNA binding site on the outside surface of the HsRad51
filament and provide a possible explanation for the regulation of DNA binding by
phosphorylation within the N-terminal domain.
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Figure 4.
Figure 4. Chemical shift pertur-
bation upon the DNA binding. (a)
Expansions of
1
H-
15
N HSQC spectra
of
15
N-labeled HsRad51(1-114) in
the absence (black contours) and
presence (red contours) of a three
molar equivalent of 12 bp double-
stranded DNA. The crosspeaks that
shift upon the addition of DNA
are indicated. (b), (c) Chemical
shift change of backbone
1
H and
15
N
calculated as [(deltad
1
H)
2
+
(deltad
15
N)
2
]
1/2
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Figure 6.
Figure 6. Structural similarity of the N-terminal
domain of HsRad51 and the six-helix barrel domain of
E. coli endonuclease III. Stereodiagram showing the
backbone superposition of HsRad51 (red, residues 26-
84) and endonuclease III (cyan, residues 31-99) (Thayer
et al., 1995). The r.m.s.d. along the C
a
atoms of residues
26-29, 32-35, 41-45, 46-49, 50-53, 55-65 and 67-84 of
HsRad51 with the corresponding part of endonuclease
III is 2.86 Å . The Figure was generated using the
program MIDASPlus (Ferrin et al., 1988).
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(1999,
290,
495-504)
copyright 1999.
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