Ultrafast Optical Studies of the Cytochrome b6f Complex in Solution and Crystalline States

  • Naranbaatar Dashdorj
  • Eiki Yamashita
  • John Schaibley
  • William A. Cramer
  • Sergei Savikhin
Conference paper

Abstract

The cytochrome b 6 f complex of oxygenic photosynthesis contains a single chlorophyll a molecule. The singlet excited state of the Chl a. molecule is quenched by the surrounding protein matrix, and thus the lifetime of this state may serve as a probe of the proteins structure. In this work, singlet excited state dynamics were measured in well-diffracting crystals using femtosecond time-resolved optical pump-probe methodology. Lifetimes of the Chl a molecule in crystals of the cytochrome b 6 f complex having different space groups were 3–6 times longer than those determined in detergent solution of the b 6 f. The observed differences in excited state dynamics may arise from small (1–1.5 Å) changes in local protein structure caused by crystal packing. The Chl a excited state lifetimes measured in dissolved cytochrome b 6 f complexes from several different species are essentially the same, in spite of differences in the local amino acid sequences around the Chl a. This supports an earlier hypothesis that the short excited state lifetime of Chl a is critical for the function of the b 6 f complex.

Keywords

Chlorophyll a cytochrome b6complex crystal packing ultrafast spectroscopy 

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References

  1. Dashdorj N, Zhang H, Kim H, Yan J, Cramer WA, Savikhin S (2005) The single chlorophyll a molecule in the cytochrome b6 f complex: Unusual optical properties protect the complex against singlet oxygen. Biophys J 88:4178-4187.PubMedCrossRefGoogle Scholar
  2. Gray HB, Winkler JR (2003) Electron tunneling through proteins. Quart Rev Biophys 36:341-372.CrossRefGoogle Scholar
  3. Page CC, Moser CC, Chen X, Dutton PL (1999) Natural engineering principles of electron tunnelling in biologi-cal oxidation-reduction. Nature 402:47-52.PubMedCrossRefGoogle Scholar
  4. Peterman EJG, Wenk S, Pullerits T, Pålsson L-O, van Grondelle R, Dekker JP, Rögner M, van Amerongen H (1998) Fluorescence and absorption spectroscopy of the weakly fluorescent chlorophyll a in cytochrome b6 f of Synechocystis PCC6803. Biophys J 75:389-398.PubMedCrossRefGoogle Scholar
  5. Savikhin S, Xu W, Soukoulis V, Chitnis PR, Struve WS (1999) Ultrafast primary processes in photosystem I of the cyanobacterium Synechocystis sp. PCC 6803. Biophys J 76:3278-3288.PubMedCrossRefGoogle Scholar
  6. Stroebel D, Choquet Y, Popot J-L, Picot D (2003) An atypical haem in the cytochrome b6 f complex. Nature 426:413-418.PubMedCrossRefGoogle Scholar
  7. Yamashita E, Zhang H, Cramer WA (2007) Structure of the cytochrome b6 f complex: Quinone analogue inhibitors as ligands of heme cn. J Mol Biol 370:39-72.PubMedCrossRefGoogle Scholar
  8. Zhang H, Cramer WA (2004) Purification and crystal-lization of the cytochrome b6 f complex in oxygenic photosynthesis. In: Carpentier R (ed) Photosynthesis Research Protocols. Humana Press, Totowa, NJ, pp 67-78.CrossRefGoogle Scholar
  9. Zhang H, Kurisu G, Smith JL, Cramer WA (2003) A defined protein-detergent-lipid complex for crystallization of integral membrane proteins: The cytochrome b6 f com-plex of oxygenic photosynthesis. Proc Natl Acad Sci USA 100:5160-5163.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science + Business Media, B.V. 2008

Authors and Affiliations

  • Naranbaatar Dashdorj
    • 1
    • 3
  • Eiki Yamashita
    • 2
    • 4
  • John Schaibley
    • 1
  • William A. Cramer
    • 2
  • Sergei Savikhin
    • 1
  1. 1.Department of PhysicsPurdue UniversityWest LafayetteUSA
  2. 2.Department of Biological SciencesPurdue UniversityWest LafayetteUSA
  3. 3.Laboratory of Chemical PhysicsNIDDK, National Institutes of HealthBethesdaUSA
  4. 4.Institute for Protein ResearchOsaka UniversityOsakaJapan

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