3ZUM

Photosynthetic Reaction Centre Mutant with Phe L146 replaced with Ala

Summary for 3ZUM

• Entry DOI: 10.2210/pdb3zum/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 2JIY 2JJ0 2RCR 2UWS 2UWT 2UWU 2UWV 2UWW 2UX3 2UX4 2UX5 2UXJ 2UXK 2UXL 2UXM 3ZUW 4RCR
• Descriptor: REACTION CENTER PROTEIN H CHAIN, SPEROIDENONE, REACTION CENTER PROTEIN L CHAIN, ... (11 entities in total)
• Functional Keywords: photosynthesis, electron transfer, primary charge separation, charge recombination, transient absorption spectroscopy
• Biological source: RHODOBACTER SPHAEROIDES; More
• Total number of polymer chains: 3
• Total formula weight: 103332.89

Authors

Gibasiewicz, K.,Pajzderska, M.,Potter, J.A.,Fyfe, P.K.,Dobek, A.,Brettel, K.,Jones, M.R. (deposition date: 2011-07-19, release date: 2011-11-16, Last modification date: 2024-05-08)

Primary citation

Gibasiewicz, K.,Pajzderska, M.,Potter, J.A.,Fyfe, P.K.,Dobek, A.,Brettel, K.,Jones, M.R.
Mechanism of Recombination of the P(+)H(A)(-) Radical Pair in Mutant Rhodobacter Sphaeroides Reaction Centers with Modified Free Energy Gaps between P(+)B(A)(-) and P(+)H(A)(-).
J Phys Chem B, 115:13037-13050, 2011

PubMed Abstract: The kinetics of recombination of the P(+)H(A)(-) radical pair were compared in wild-type reaction centers from Rhodobacter sphaeroides and in seven mutants in which the free energy gap, ΔG, between the charge separated states P(+)B(A)(-) and P(+)H(A)(-) was either increased or decreased. Five of the mutant RCs had been described previously, and X-ray crystal structures of two newly constructed complexes were determined by X-ray crystallography. The charge recombination reaction was accelerated in all mutants with a smaller ΔG than in the wild-type, and was slowed in a mutant having a larger ΔG. The free energy difference between the state P(+)H(A)(-) and the PH(A) ground state was unaffected by most of these mutations. These observations were consistent with a model in which the P(+)H(A)(-) → PH(A) charge recombination is thermally activated and occurs via the intermediate state P(+)B(A)(-), with a mean rate related to the size of the ΔG between the states P(+)B(A)(-) and P(+)H(A)(-) and not the ΔG between P(+)H(A)(-) and the ground state. A more detailed analysis of charge recombination in the mutants showed that the kinetics of the reaction were multiexponential, and characterized by ~0.5, ~1-3, and 7-17 ns lifetimes, similar to those measured for wild-type reaction centers. The exact lifetimes and relative amplitudes of the three components were strongly modulated by the mutations. Two models were considered in order to explain the observed multiexponentiality and modulation, involving heterogeneity or relaxation of P(+)H(A)(-) states, with the latter model giving a better fit to the experimental results.

PubMed: 21970763
DOI: 10.1021/JP206462G

Experimental method

X-RAY DIFFRACTION (2.5 Å)