1AIJ image
Entry Detail
PDB ID:
1AIJ
Title:
PHOTOSYNTHETIC REACTION CENTER FROM RHODOBACTER SPHAEROIDES IN THE CHARGE-NEUTRAL DQAQB STATE
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
1997-04-18
Release Date:
1997-10-22
Method Details:
Experimental Method:
Resolution:
2.20 Å
R-Value Free:
0.27
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
P 43 21 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:PHOTOSYNTHETIC REACTION CENTER (H SUBUNIT)
Chain IDs:C (auth: H), F (auth: T)
Chain Length:260
Number of Molecules:2
Biological Source:Rhodobacter sphaeroides
Polymer Type:polypeptide(L)
Description:PHOTOSYNTHETIC REACTION CENTER (L SUBUNIT)
Chain IDs:A (auth: L), D (auth: R)
Chain Length:281
Number of Molecules:2
Biological Source:Rhodobacter sphaeroides
Polymer Type:polypeptide(L)
Description:PHOTOSYNTHETIC REACTION CENTER (M SUBUNIT)
Chain IDs:B (auth: M), E (auth: S)
Chain Length:307
Number of Molecules:2
Biological Source:Rhodobacter sphaeroides
Primary Citation

Abstact

High resolution x-ray diffraction data from crystals of the Rhodobacter sphaeroides photosynthetic reaction center (RC) have been collected at cryogenic temperature in the dark and under illumination, and the structures were refined at 2.2 and 2.6 angstrom resolution, respectively. In the charge-separated D+QAQB- state (where D is the primary electron donor (a bacteriochlorophyll dimer), and QA and QB are the primary and secondary quinone acceptors, respectively), QB- is located approximately 5 angstroms from the QB position in the charge-neutral (DQAQB) state, and has undergone a 180 degrees propeller twist around the isoprene chain. A model based on the difference between the two structures is proposed to explain the observed kinetics of electron transfer from QA-QB to QAQB- and the relative binding affinities of the different ubiquinone species in the QB pocket. In addition, several water channels (putative proton pathways) leading from the QB pocket to the surface of the RC were delineated, one of which leads directly to the membrane surface.

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