2UXK

X-ray high resolution structure of the photosynthetic reaction center from Rb. sphaeroides at pH 10 in the charge-separated state

Summary for 2UXK

• Entry DOI: 10.2210/pdb2uxk/pdb
• Related: 1AIG 1AIJ 1DS8 1DV3 1DV6 1E14 1E6D 1F6N 1FNP 1FNQ 1JGW 1JGX 1JGY 1JGZ 1JH0 1K6L 1K6N 1KBY 1L9B 1L9J 1M3X 1MPS 1OGV 1PCR 1PSS 1PST 1QOV 1RG5 1RGN 1RQK 1RVJ 1RY5 1RZH 1RZZ 1S00 1UMX 1YST 1Z9J 1Z9K 2BNP 2BNS 2BOZ 2GMR 2J8C 2J8D 2RCR 2UWS 2UWT 2UWU 2UWV 2UWW 2UX3 2UX4 2UX5 2UXJ 2UXL 2UXM 4RCR
• Descriptor: REACTION CENTER PROTEIN H CHAIN, HEPTANE-1,2,3-TRIOL, FE (III) ION, ... (15 entities in total)
• Functional Keywords: chlorophyll, cardiolipin, metal-binding, transmembrane, photosynthesis, reaction center, electron transport, iron, membrane, magnesium, transport, chromophore, binding positions of the secondary quinone qb, bacteriochlorophyll, proton translocation pathways
• Biological source: RHODOBACTER SPHAEROIDES; More
• Total number of polymer chains: 3
• Total formula weight: 105458.70

Authors

Koepke, J.,Diehm, R.,Fritzsch, G. (deposition date: 2007-03-28, release date: 2007-07-03, Last modification date: 2023-12-13)

Primary citation

Koepke, J.,Krammer, E.M.,Klingen, A.R.,Sebban, P.,Ullmann, G.M.,Fritzsch, G.
Ph Modulates the Quinone Position in the Photosynthetic Reaction Center from Rhodobacter Sphaeroides in the Neutral and Charge Separated States.
J.Mol.Biol., 371:396-, 2007

PubMed Abstract: 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.

PubMed: 17570397
DOI: 10.1016/J.JMB.2007.04.082

Experimental method

X-RAY DIFFRACTION (2.31 Å)