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PDBsum entry 2bns
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Photosynthesis
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PDB id
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2bns
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Contents |
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281 a.a.
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302 a.a.
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237 a.a.
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References listed in PDB file
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Key reference
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Title
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Conformational regulation of charge recombination reactions in a photosynthetic bacterial reaction center.
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Authors
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G.Katona,
A.Snijder,
P.Gourdon,
U.Andréasson,
O.Hansson,
L.E.Andréasson,
R.Neutze.
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Ref.
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Nat Struct Mol Biol, 2005,
12,
630-631.
[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
perfect match.
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Abstract
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In bright light the photosynthetic reaction center (RC) of Rhodobacter
sphaeroides stabilizes the P(+)(870).Q(-)(A) charge-separated state and thereby
minimizes the potentially harmful effects of light saturation. Using X-ray
diffraction we report a conformational change that occurs within the cytoplasmic
domain of this RC in response to prolonged illumination with bright light. Our
observations suggest a novel structural mechanism for the regulation of electron
transfer reactions in photosynthesis.
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Figure 1.
Figure 1. Electron transfer reactions within the RC. Time
scales are indicated. In bright light the recombination of the
P+[870]  Q-[A]
charge-separated state is slowed from 100 ms to 250 s (red
arrow).
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Figure 2.
Figure 2. Structural changes within the RC in response to bright
light. (a) Reproducible difference electron density features
(yellow, negative density; blue, positive density) are large
spheres (observed in all six difference Fourier maps) and small
spheres (observed in five of six). Statistics are given in
Supplementary Table 2 online. Arginines with increased trypsin
susceptibility in bright light are red, and those with decreased
susceptibility are blue. The H subunit is cyan. (b) Refined
structural changes. Arrowheads indicate the relative magnitude
and direction of the movements (blue, positively charged
residues; red, negatively charged residues; gray, every fifth
residue). Surface-exposed histidines are green, buried water
molecules red and the C-terminal  -helix
gray. The subdomain from Pro121H to Thr226H (purple) experiences
a net electrostatic force (yellow vector) due to interactions
with Q-[A] (red).
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Mol Biol
(2005,
12,
630-631)
copyright 2005.
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