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PDBsum entry 1h2s
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Membrane protein
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PDB id
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1h2s
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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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Molecular basis of transmembrane signalling by sensory rhodopsin ii-Transducer complex.
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Authors
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V.I.Gordeliy,
J.Labahn,
R.Moukhametzianov,
R.Efremov,
J.Granzin,
R.Schlesinger,
G.Büldt,
T.Savopol,
A.J.Scheidig,
J.P.Klare,
M.Engelhard.
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Ref.
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Nature, 2002,
419,
484-487.
[DOI no: ]
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PubMed id
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Abstract
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Microbial rhodopsins, which constitute a family of seven-helix membrane proteins
with retinal as a prosthetic group, are distributed throughout the Bacteria,
Archaea and Eukaryota. This family of photoactive proteins uses a common
structural design for two distinct functions: light-driven ion transport and
phototaxis. The sensors activate a signal transduction chain similar to that of
the two-component system of eubacterial chemotaxis. The link between the
photoreceptor and the following cytoplasmic signal cascade is formed by a
transducer molecule that binds tightly and specifically to its cognate receptor
by means of two transmembrane helices (TM1 and TM2). It is thought that light
excitation of sensory rhodopsin II from Natronobacterium pharaonis (SRII) in
complex with its transducer (HtrII) induces an outward movement of its helix F
(ref. 6), which in turn triggers a rotation of TM2 (ref. 7). It is unclear how
this TM2 transition is converted into a cellular signal. Here we present the
X-ray structure of the complex between N. pharaonis SRII and the
receptor-binding domain of HtrII at 1.94 A resolution, which provides an atomic
picture of the first signal transduction step. Our results provide evidence for
a common mechanism for this process in phototaxis and chemotaxis.
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Figure 2.
Figure 2: Fold of the receptor -transducer complex a, Ribbon
diagram of the top view from the cytoplasmic side.  -Helices
are in red for the receptor and green for the transducer;  -strands
are in blue and coils in grey.The labels of the symmetry related
complex are marked by a prime. The crystallographic symmetry
axis is located between TM1 -TM2 and TM1' -TM2'. b, Side view of
the complex. The complex is coloured according to B-factor
mobility: light red/green (less mobile), dark red/green
(mobile). ES, extracellular side; CS, cytoplasmic side. The
dotted white lines confine the major hydrophobic core of the
proteins. Of note, the actual membrane boundary will not follow
these straight lines. The arrows indicate the shortened stalk in
HtrI (white) and the site where the helices 1
and 4
of the chemoreceptor domain of H. salinarum HtrII are attached
to the transmembrane helices TM1 and TM2 (blue). All figures
were generated with MOLSCRIPT and Raster3D.
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Figure 3.
Figure 3: Stereo view of the hydrogen bonds and van der Waals
contacts between receptor ( alpha- -helices
in red) and transducer ( alpha--helices
in green). The residues that are involved in hydrogen bonds
are labelled.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nature
(2002,
419,
484-487)
copyright 2002.
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