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PDBsum entry 1ixr
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Contents |
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135 a.a.
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191 a.a.
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308 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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Crystal structure of the ruva-Ruvb complex: a structural basis for the holliday junction migrating motor machinery.
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Authors
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K.Yamada,
T.Miyata,
D.Tsuchiya,
T.Oyama,
Y.Fujiwara,
T.Ohnishi,
H.Iwasaki,
H.Shinagawa,
M.Ariyoshi,
K.Mayanagi,
K.Morikawa.
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Ref.
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Mol Cell, 2002,
10,
671-681.
[DOI no: ]
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PubMed id
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Abstract
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We present the X-ray structure of the RuvA-RuvB complex, which plays a crucial
role in ATP-dependent branch migration. Two RuvA tetramers form the symmetric
and closed octameric shell, where four RuvA domain IIIs spring out in the two
opposite directions to be individually caught by a single RuvB. The binding of
domain III deforms the protruding beta hairpin in the N-terminal domain of RuvB
and thereby appears to induce a functional and less symmetric RuvB hexameric
ring. The model of the RuvA-RuvB junction DNA ternary complex, constructed by
fitting the X-ray structure into the averaged electron microscopic images of the
RuvA-RuvB junction, appears to be more compatible with the branch migration mode
of a fixed RuvA-RuvB interaction than with a rotational interaction mode.
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Figure 4.
Figure 4. Averaged Electron Microscopic Image of the
RuvA-RuvB-Holliday Junction Ternary Complex and the
Corresponding Functional Atomic ModelThe IMAGIC program package
(van Heel et al., 1996) was used to cluster particle images and
to obtain class averages. The hypothetical model was constructed
by fitting the RuvA octameric core structure (yellow) and the
RuvB hexamer models (blue) into the averaged images, referring
to the hexameric oligomerization of the HslU protein similar to
RuvB (Sousa et al., 2000). One pair of subunits related in
each hexameric ring by the central 2-fold axis was replaced by
the two domain III (orange)-RuvB (magenta) complexes (see text).
Averaged electron microscopic images correspond to two
orthogonal views of the ternary complex. The 858 original
images were grouped into three major classes of averaged images,
and only two of them, (A) and (B), averaged from 171 and 370
electron microscopic images, are shown here. Note the good
coincidence of the images with the side (A) and end views (B) of
the RuvA octameric core structure. The resolutions of the
averaged images of (A) and (B) were estimated at 34 and 31
Å, respectively, from differential phase residuals. The
scale bar represents 100 Å.
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Figure 5.
Figure 5. Model of the Loading Process of the RuvA-RuvB
Complex on a Holliday JunctionEach of the three components in
this process was determined by X-ray analyses (forms I, II, and
III) or by an electron microscopic study (form IV). The RuvA
core region and domain III are colored by yellow and orange,
respectively. The RuvB subunit is depicted by a blue oval.
Red-trimmed ovals represent domain III bound to the RuvB
subunit. The RuvA-RuvB complex (form III) is regarded as the
preloading complex before forming the functional complex on a
Holliday junction (form IV). During the conversion from form III
to IV, the RuvB subunit that was previously connected with the
RuvA octameric core is no longer replaced by other partners.
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The above figures are
reprinted
by permission from Cell Press:
Mol Cell
(2002,
10,
671-681)
copyright 2002.
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