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PDBsum entry 1kq1
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Contents |
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(+ 5 more)
60 a.a.
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66 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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Structures of the pleiotropic translational regulator hfq and an hfq-Rna complex: a bacterial sm-Like protein.
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Authors
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M.A.Schumacher,
R.F.Pearson,
T.Møller,
P.Valentin-Hansen,
R.G.Brennan.
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Ref.
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EMBO J, 2002,
21,
3546-3556.
[DOI no: ]
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PubMed id
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Abstract
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In prokaryotes, Hfq regulates translation by modulating the structure of
numerous RNA molecules by binding preferentially to A/U-rich sequences. To
elucidate the mechanisms of target recognition and translation regulation by
Hfq, we determined the crystal structures of the Staphylococcus aureus Hfq and
an Hfq-RNA complex to 1.55 and 2.71 A resolution, respectively. The structures
reveal that Hfq possesses the Sm-fold previously observed only in eukaryotes and
archaea. However, unlike these heptameric Sm proteins, Hfq forms a
homo-hexameric ring. The Hfq-RNA structure reveals that the single-stranded
hepta-oligoribonucleotide binds in a circular conformation around a central
basic cleft, whereby Tyr42 residues from adjacent subunits stack with six of the
bases, and Gln8, outside the Sm motif, provides key protein-base contacts. Such
binding suggests a mechanism for Hfq function.
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Figure 1.
Figure 1 The structure of Hfq. (A) Structure of the Hfq monomer
shown as a ribbon diagram. Secondary structural elements are
labeled, as are the first (N) and last (C) residues observed.
Figures 1A−C, 2B−D, 3A, 4B and C and 6 were made with
Swiss-PdbViewer and rendered with POVRAY (Guex and Peitsch,
1997; POVRAY, Persistence of Vision Raytracer version 3.1
http://www.povray.org). (B) Structure of the Hfq hexamer with
each subunit colored differently. (C) The two Hfq hexamers in
the crystallographic asymmetric unit. This view is rotated
90° to (B) along the vertical axis in the plane of the
paper. Interactions between the two rings are made by residues
from the hydrophobic surface of each hexamer (see Figure 5B).
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Figure 6.
Figure 6 RNA recognition by Hfq. Cross-eyed stereo view of the
5' adenine- and uracil-binding pockets. Hydrogen bonds are shown
as black lines. All residues that contact the nucleotide are
located within the Sm1 and Sm2 motifs (shown as sticks), with
the exception of conserved residue Gln8, which is located on
helix  1
and colored according to atom type (blue, red and yellow for
nitrogen, oxygen and carbon).
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The above figures are
reprinted
from an Open Access publication published by Macmillan Publishers Ltd:
EMBO J
(2002,
21,
3546-3556)
copyright 2002.
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