1f6n

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spinqualitylabelsall models 1f6n, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTAL STRUCTURE ANALYSIS OF THE MUTANT REACTION CENTER PRO L209-> TYR FROM THE PHOTOSYNTHETIC PURPLE BACTERIUM RHODOBACTER SPHAEROIDES

Overview

The structures of the reaction center variants Pro L209 --> Tyr, Pro L209, --> Phe, and Pro L209 --> Glu from the photosynthetic purple bacterium, Rhodobacter sphaeroides have been determined by X-ray crystallography to, 2.6-2.8 A resolution. These variants were constructed to interrupt a chain, of tightly bound water molecules that was assumed to facilitate proton, transfer from the cytoplasm to the secondary quinone Q(B) [Baciou, L., and, Michel, H. (1995) Biochemistry 34, 7967-7972]. However, the amino acid, exchanges Pro L209 --> Tyr and Pro L209 --> Phe do not interrupt the water, chain. Both aromatic side chains are oriented away from this water chain, and interact with three surrounding polar side chains (Asp L213, Thr L226, and Glu H173) which are displaced by up to 2.6 A. The conformational, changes induced by the bulky aromatic rings of Tyr L209 and Phe L209 lead, to unexpected displacements of Q(B) compared to the wild-type protein. In, the structure of the Pro L209 --> Tyr variant, Q(B) is shifted by, approximately 4 A and is now located at a position similar to that, reported for the wild-type reaction center after illumination [Stowell, M., H. B., et al. (1997) Science 276, 812-816]. In the Pro L209 --> Phe, variant, the electron density map reveals an intermediate Q(B) position, between the binding sites of the wild-type protein in the dark and the Pro, L209 --> Tyr protein. In the Pro L209 --> Glu reaction center, the, carboxylic side chain of Glu L209 is located within the water chain, and, the binding site of Q(B) remains unchanged compared to the wild-type, structure.

About this Structure

1F6N is a Protein complex structure of sequences from Rhodobacter sphaeroides with FE, PO4, BCL, BPH, U10, SPO and LDA as ligands. Full crystallographic information is available from OCA.

Reference

X-ray structure analyses of photosynthetic reaction center variants from Rhodobacter sphaeroides: structural changes induced by point mutations at position L209 modulate electron and proton transfer., Kuglstatter A, Ermler U, Michel H, Baciou L, Fritzsch G, Biochemistry. 2001 Apr 10;40(14):4253-60. PMID:11284681

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