1YF6

Structure of a quintuple mutant of photosynthetic reaction center from rhodobacter sphaeroides

Summary for 1YF6

• Entry DOI: 10.2210/pdb1yf6/pdb
• Related: 1QOV 1RZH
• Descriptor: Reaction center protein L chain, FE (II) ION, CHLORIDE ION, ... (15 entities in total)
• Functional Keywords: bacterial photosynthesis, rhodobacter sphaeroides, gated electron transfer, quinone movement, integral 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: 105288.87

Authors

Paddock, M.L.,Chang, C.,Xu, Q.,Abresch, E.C.,Axelrod, H.L. (deposition date: 2004-12-30, release date: 2005-05-17, Last modification date: 2023-08-23)

Primary citation

Paddock, M.L.,Chang, C.,Xu, Q.,Abresch, E.C.,Axelrod, H.L.,Feher, G.,Okamura, M.Y.
Quinone (Q(B)) Reduction by B-Branch Electron Transfer in Mutant Bacterial Reaction Centers from Rhodobacter sphaeroides: Quantum Efficiency and X-ray Structure.
Biochemistry, 44:6920-6928, 2005

PubMed Abstract: The photosynthetic reaction center (RC) from purple bacteria converts light into chemical energy. Although the RC shows two nearly structurally symmetric branches, A and B, light-induced electron transfer in the native RC occurs almost exclusively along the A-branch to a primary quinone electron acceptor Q(A). Subsequent electron and proton transfer to a mobile quinone molecule Q(B) converts it to a quinol, Q(B)H(2). We report the construction and characterization of a series of mutants in Rhodobacter sphaeroides designed to reduce Q(B) via the B-branch. The quantum efficiency to Q(B) via the B-branch Phi(B) ranged from 0.4% in an RC containing the single mutation Ala-M260 --> Trp to 5% in a quintuple mutant which includes in addition three mutations to inhibit transfer along the A-branch (Gly-M203 --> Asp, Tyr-M210 --> Phe, Leu-M214 --> His) and one to promote transfer along the B-branch (Phe-L181 --> Tyr). Comparing the value of 0.4% for Phi(B) obtained in the AW(M260) mutant, which lacks Q(A), to the 100% quantum efficiency for Phi(A) along the A-branch in the native RC, we obtain a ratio for A-branch to B-branch electron transfer of 250:1. We determined the structure of the most effective (quintuple) mutant RC at 2.25 A (R-factor = 19.6%). The Q(A) site did not contain a quinone but was occupied by the side chain of Trp-M260 and a Cl(-). In this structure a nonfunctional quinone was found to occupy a new site near M258 and M268. The implications of this work to trap intermediate states are discussed.

PubMed: 15865437
DOI: 10.1021/bi047559m

Experimental method

X-RAY DIFFRACTION (2.25 Å)