2ux5

File:2ux5.jpg

spinqualitylabelsall models PDB ID 2ux5 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
, resolution 2.21Å
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Ligands:	, , , , , , , , , and
Coordinates:	save as pdb, mmCIF, xml

X-RAY HIGH RESOLUTION STRUCTURE OF THE PHOTOSYNTHETIC REACTION CENTER FROM RB. SPHAEROIDES AT PH 9 IN THE CHARGE-SEPARATED STATE

OverviewOverview

The structure of the photosynthetic reaction-center from Rhodobacter sphaeroides has been determined at four different pH values (6.5, 8.0, 9.0, 10.0) in the neutral and in charge separated states. At pH 8.0, in the neutral state, we obtain a resolution of 1.87 A, which is the best ever reported for the bacterial reaction center protein. Our crystallographic data confirm the existence of two different binding positions of the secondary quinone (QB). We observe a new orientation of QB in its distal position, which shows no ring-flip compared to the orientation in the proximal position. Datasets collected for the different pH values show a pH-dependence of the population of the proximal position. The new orientation of QB in the distal position and the pH-dependence could be confirmed by continuum electrostatics calculations. Our calculations are in agreement with the experimentally observed proton uptake upon charge separation. The high resolution of our crystallographic data allows us to identify new water molecules and external residues being involved in two previously described hydrogen bond proton channels. These extended proton-transfer pathways, ending at either of the two oxo-groups of QB in its proximal position, provide additional evidence that ring-flipping is not required for complete protonation of QB upon reduction.

About this StructureAbout this Structure

2UX5 is a Protein complex structure of sequences from Rhodobacter sphaeroides. Full crystallographic information is available from OCA.

ReferenceReference

pH modulates the quinone position in the photosynthetic reaction center from Rhodobacter sphaeroides in the neutral and charge separated states., Koepke J, Krammer EM, Klingen AR, Sebban P, Ullmann GM, Fritzsch G, J Mol Biol. 2007 Aug 10;371(2):396-409. Epub 2007 May 10. PMID:17570397

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