1K6L

Photosynethetic Reaction Center from Rhodobacter sphaeroides

Summary for 1K6L

• Entry DOI: 10.2210/pdb1k6l/pdb
• Related: 1k6n 1pcr 1qov 2rcr
• Descriptor: PHOTOSYNTHETIC REACTION CENTER L SUBUNIT, CARDIOLIPIN, PHOTOSYNTHETIC REACTION CENTER M SUBUNIT, ... (11 entities in total)
• Functional Keywords: photosynthetic reaction center, membrane protein, photosynthesis
• Biological source: Rhodobacter sphaeroides; More
• Cellular location: Cellular chromatophore membrane; Multi-pass membrane protein: P02954 P02953; Cellular chromatophore membrane; Single-pass membrane protein: P11846
• Total number of polymer chains: 3
• Total formula weight: 104961.89

Authors

Pokkuluri, P.R.,Laible, P.D.,Deng, Y.-L.,Wong, T.N.,Hanson, D.K.,Schiffer, M. (deposition date: 2001-10-16, release date: 2002-08-07, Last modification date: 2023-08-16)

Primary citation

Pokkuluri, P.R.,Laible, P.D.,Deng, Y.L.,Wong, T.N.,Hanson, D.K.,Schiffer, M.
The structure of a mutant photosynthetic reaction center shows unexpected changes in main chain orientations and quinone position.
Biochemistry, 41:5998-6007, 2002

PubMed Abstract: We report on the unexpected structural changes caused by substitution of acidic amino acids in the Q(B) binding pocket of the bacterial photosynthetic reaction center by alanines. The mutations targeted key residues L212Glu and L213Asp of this transmembrane protein-cofactor complex. The amino acid substitutions in the L212Ala-L213Ala mutant reaction center ("AA") were known to affect the delivery of protons after the light-induced generation of Q(B)(-), which renders the AA strain incapable of photosynthetic growth. The AA structure not only revealed side chain rearrangements but also showed movement of the main chain segments that are contiguous with the mutation sites. The alanine substitutions caused an expansion of the cavity rather than its collapse. In addition, Q(B) is found mainly in the binding site that is proximal to the iron-ligand complex (closest to Q(A)) as opposed to its distal binding site (furthest from Q(A)) in the structure of the wild-type reaction center. The observed rearrangements in the structure of the AA reaction center establish a new balance between charged residues of an interactive network near Q(B). This structurally and electrostatically altered complex forms the basis for future understanding of the structural basis for proton transfer in active reaction centers which retain the alanine substitutions but carry a distant compensatory mutation.

PubMed: 11993994
DOI: 10.1021/bi0118963

Experimental method

X-RAY DIFFRACTION (3.1 Å)