Charges Recombination Kinetics in Bacterial Photosynthetic Reaction Centers: Conformational States in Equilibrium Pre-Exist in the Dark

  • Barbara Schoepp
  • Pierre Parot
  • Jean Lavorel
  • André Verméglio
Chapter
Part of the Nato ASI Series book series (NSSA, volume 237)

Abstract

In whole bacterial cells (or in chromatophores) treated with orthophenantrolin, or in purified reaction centers, RCs, prepared with only one quinone acceptor, QA, the P+Q A - state resulting from the photochemical charge separation only decays by recombination (P+Q A - → PQA). Several years ago, we have studied the complex wavelength dependence of the P+Q A - decay at cryogenic temperatures and revealed its biphasicity for RCs and chromatophores of Rhodobacter sphaeroides and Rhodospirillum rubrum. In order to explain this biphasicity we proposed that the RCs were present in two conformational states1,2,3. On the other hand, for these same species, at room temperature, the decay is monophasic, suggesting that under this condition the two conformational states can equilibrate rapidly4. Numerous instances of polyphasic kinetics in bacterial systems have been documented. Biphasicity of charge recombination from P+Q A - or P+Q B - at room temperature has been reported in Rhodopseudomonas viridis RCs5,6,7 and Rhodobacter sphaeroides RCs where the native ubiquinone has been replaced by anthraquinone8. The above results have been interpreted as originating from two distinct conformational states pre-existing the excitation flash. In the nanosecond time range, Woodbury and Parson9 have observed polyphasic fluorescence decay. Careful analysis of the formation and decay of the P+I- state shows that these events appear with a range of time constants depending on the detecting wavelength10. In Chloroflexus aurantiacus at low temperature, the decay of P* is clearly non-exponential11. A proposed possible explanation of this heterogeneity could be a rapid interconversion among a distribution of conformational states in the excited state P*

Keywords

Recombination Photosynthesis HUll Quinone Phosphatidylcholine 

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References

  1. 1.
    P. Parot, J. Thicry and A. Vermcglio, Charge recombination ai low temperature in photosynthetic bacterial reaction centers: evidence for two conformational states, Biochim. Biophys. Acta 893: 534 (1987).CrossRefGoogle Scholar
  2. 2.
    P. Parot, J. Thiery and A. Vermeglio, Charge recombination at low temperature in photosynthetic bacteria reaction centers, in: “The Photosynthetic Bacterial Reaction Center Structure and dynamics”: 251, J. Breton and A. Verm6glio eds., Plenum Publishing Corporation, New-York-London (1988).CrossRefGoogle Scholar
  3. 3.
    P. Sebban, P. Parot, L. Baciou, P. Mathis and A. Vermeglio, Effects of low temperature and lipid rigidity on the charge recombination process in Rps. viridis and Rb. sphaeroides reaction centers, Biochim. Biophys. Acta 1057: 109 (1991).CrossRefGoogle Scholar
  4. 4.
    D. Kleinfeld, M.Y. Okamura and G. Feher, Electron-transfert in photosynthetic reaction centers cooled to cryogenic temperatures in charge-separated state: evidence for light-induced structural changes, Biochemistry 23: 5780 (1984).PubMedCrossRefGoogle Scholar
  5. 5.
    L. Baciou, E. Rivas and P. Sebban, P+QA- and P+QB- charge recombinations in Rps. viridis chromatophores and in reaction centers reconstituted in phosphatidylcholine liposomes. Existence of two conformational states of reaction centers and effects of pH and 0-phenanthroline, Biochemistry 29: 2966 (1990).PubMedCrossRefGoogle Scholar
  6. 6.
    P. Sebban and C. Wraight, Heterogeneity of the P+QA- recombination kinetics in reaction centers from Rps. viridis: the effects of pH and temperature, Biochim. Biophys. Acta 91A: 54 (1989).Google Scholar
  7. 7.
    J-L. Gao, R. J. Shopes and C. Wraight, Heterogeneity of kinetics and electron transfert equilibria in the bacteriopheophytin and quinone electron acceptors of reaction centers from Rps. viridis, Biochim. Biophys. Acta 1056: 259 (1991).CrossRefGoogle Scholar
  8. 8.
    P. Sebban, PH effect on the biphasicity of the P+QA- charge recombination kinetics in the reaction centers from Rb. sphaeroides, reconstituted with anthraquinones, Biochim. Biophys. Acta 936: 124 (1988).CrossRefGoogle Scholar
  9. 9.
    N.W. Woodbury and W.W. Parson, Nanosecond fluorescence from isolated photosynthetic reaction centers of Rps. sphaeroides, Biochim. Biophys. Acta 767: 345 (1984).PubMedCrossRefGoogle Scholar
  10. 10.
    C. Kirmaier and D. Holten, Evidence that a distribution of bacterial reaction centers underlies the temperature and detection-wavelength dependence of the rates of the primary electron-tranfert reactions, Proc. Natl. Acad. Sci. USA 87: 3552 (1990).PubMedCrossRefGoogle Scholar
  11. 11.
    M. Becker, V. Nagarajan, D. Middendorf, W.W. Parson, J.E. Martin and R.E. Blankenship, Temperature dependence of the initial electron-transfert kinetics in photosynthetic reaction centers of C. aurantiacus, Biochim. Biophys. Acta 1057: 299 (1991).CrossRefGoogle Scholar
  12. 12.
    S. Franzen, R.F. Goldstein and S.G. Boxer, Electric field modulation of electron transfert reaction rates in isotropic systems: long-distance charge recombination in photosynthetic reaction centers, J. Phys. Chem. 94:5135(1990).CrossRefGoogle Scholar
  13. 13.
    J J. Hopfield, Electron transfert between biological molecules by thermally activated tunneling, Proc. Nat. Acad. Sci. USA 71: 3640 (1974).PubMedCrossRefGoogle Scholar
  14. 14.
    J. Jortner, Dynamics of electron transfert in bacterial photosynthesis, Biochim. Biophys. Acta 594: 193 (1980).PubMedCrossRefGoogle Scholar
  15. 15.
    S.N. Deming and S.L. Morgan, Simplex optimisation of variables in analytical chemistry, Anal. Chem. 45:278A (1973).Google Scholar
  16. 16.
    J. Thiery, Personal communication.Google Scholar

Copyright information

© Springer Science+Business Media New York 1992

Authors and Affiliations

  • Barbara Schoepp
    • 1
  • Pierre Parot
    • 1
  • Jean Lavorel
    • 1
  • André Verméglio
    • 1
  1. 1.DPVE/SBCC.E. CadaracheSaint-Paul-lez-DuranceFrance

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