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2005 Fiscal Year Final Research Report Summary

Study on mechanisms of inter- and intra-cytochromes electron transfer in primary reactions of photosynthesis

Research Project

Project/Area Number 16570035
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 植物生理・分子
Research InstitutionTokyo Metropolitan University

Principal Investigator

NAGASHIMA Kenji  Tokyo Metropolitan Univ., Dept.Biology, Assistant Prof., 都市教養学部理工学系, 助手 (80264589)

Project Period (FY) 2004 – 2005
KeywordsPhotosynthesis / Electron transfer / Cytochrome / Reaction center / Rredox midpoint potential / Site-directed mutagenesis / Charges amino acids / Photosynthetic bacteria
Research Abstract

Site-directed mutations have been introduced into the tetraheme cytochrome subunit in the chimeric reaction center complex composed of that from the purple bacterium, Blastochioris viridis, and core subunits from other purple bacterium, Rubrivivax gelatinosus. About 50 mutants have been constructed and analyzed with methods of time-resolved spectroscopy. Results obtained are follows.
1. It was shown that the physiological electron donor, cytochrome c_2, donates an electron to the most distal heme from the core among the 4 hemes. When the cytochrome recognizes its reaction partner, electrostatic interaction between the surfaces of them is the most important driving force. The distribution of the charges important for the interaction was mapped on the structure of the tetraheme cytochrome.
2. The redox midpoint potentials of hemes in the tetraheme cytochrome were successfully changed up to 400mV by changing the net charges of the amino acid residues positioned near the hemes and away from the protein surface. Changing the amino acid working as an axial ligand to the heme iron, methionine, to cysteine caused about 450mV downshift in the midpoint potential.
3. The midpoint potentials of hemes are sequenced as -60, 310, 60 and 400mV from the outside to the core in the original chimeric reaction center. The highest potential heme in one of the mutants was lowered from 400mV to 0mV, resulted in a change of the redox profile of 4 hemes from low-high-low-high to low-high-low-low. In this mutant the rate of electron transfer to the chlorophyll dimer was about 100 times slower than that in the original chimera. This shows that the low-potential hemes intermediate the electron transfer in spite of their unfavorable energy level and supports a kinetic model that an electron is transferred through a thermodynamic "roller coaster" if a sufficient potential difference is kept between the end donor and the end acceptor.

  • Research Products

    (12 results)

All 2006 2005 2004

All Journal Article (12 results)

  • [Journal Article] Kinetic Performance and Energy Profile in a Roller Coaster Election Transfer Chain : A Study of Modified Tetraheme-Reaction Center Constructs2006

    • Author(s)
      Alric, J.
    • Journal Title

      Journal of the American Chemical Society 128

      Pages: 4136-4145

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Kinetic Performance and Energy Profile in a Roller Coaster Electron Transfer Chain : A Study of Modified Tetraheme-Reaction Center Constructs2006

    • Author(s)
      Alric, J. et al.
    • Journal Title

      Journal of the American Chemical Society 128

      Pages: 4136-4145

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Structural and spectroscopic properties of a reaction center complex from the chlorosome-lacking filamentous anoxygenic phototrophic bacterium Roseiflexus castenholzii2005

    • Author(s)
      Yamada, M.
    • Journal Title

      Journal of Bacteriology 187

      Pages: 1702-1709

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Changes in midpoint potentials of hemes by SD-mutagenesis in RC-bound tetraheme cytochrome of Blastochloris viridis2005

    • Author(s)
      Nagashima, K. V. P
    • Journal Title

      Photosynthesis : Fundamental Aspects to Global Perspectives, Alliance Communications Group, Kansas

      Pages: 325-327

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Structural and spectroscopic properties of a reaction center complex from the chlorosome-lacking filamentous anoxygenic phototrophic bacterium Roseiflexus castenholzii2005

    • Author(s)
      Yamada, M. et al.
    • Journal Title

      Journal of Bacteriology 187

      Pages: 1702-1709

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Changes in midpoint potentials of hemes by SD-mutagenesis in RC-bound tetraheme cytochrome of Blastochioris viridis2005

    • Author(s)
      Nagashima, K.V.P. et al.
    • Journal Title

      Photosynthesis : Fundamental Aspects to Global Perspectives (Alliance Communications Group, Kansas)

      Pages: 325-327

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Structural and functional characterization of the unusual triheme cytochrome bound to the reaction center of Rhodovulum sulfidophilum2004

    • Author(s)
      Alric, J.
    • Journal Title

      Journal of Biological Chemistry 279

      Pages: 26090-26097

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Two distinct binding sites for high potential iron-sulfer protein and cytochrome c on the reaction center-bound cytochrome of Rubrivivax gelationosus2004

    • Author(s)
      Alric, J.
    • Journal Title

      Journal of Biological Chemistry 279

      Pages: 32545-32553

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Electrostatic interaction between redox confactors in photosynthetic reaction centers2004

    • Author(s)
      Alric, J.
    • Journal Title

      Journal of Biological Chemistry 279

      Pages: 47849-47855

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Structural and functional characterization of the unusual triheme cytochrome bound to the reaction center of Rhodovulum sulfidophilum2004

    • Author(s)
      Alric, J. et al.
    • Journal Title

      Journal of Biological Chemistry 279

      Pages: 26090-26097

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Two distinct binding sites for high potential iron-sulfur protein and cytochrome c on the reaction center-bound cytochrome of Rubrivivax gelatinosus2004

    • Author(s)
      Alric, J. et al.
    • Journal Title

      Journal of Biological Chemistry 279

      Pages: 32545-32553

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Electrostatic interaction between redox cofactors in photosynthetic reaction centers2004

    • Author(s)
      Alric, J. et al.
    • Journal Title

      Journal of Biological Chemistry 279

      Pages: 47849-47855

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2007-12-13  

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