Identification of the Plastocyanin Binding Subunit of Photosystem I

  • Michael Hippler
  • Rafael Ratajczak
  • Wolfgang Haehnel

Abstract

A photosystem (PS) I complex being competent in mediating the electron transfer from plastocyanin (PCy) to ferredoxin is assembled from more than 7 subunits [1]. The two large chlorophyll (chl) a containing subunits Ia and Ib are plastid encoded and carry the primary electron donor P700 and the electron acceptors A0, phylloquinone and Fe-SX. Subunit VII carries the electron acceptors Fe-SA and Fe-SB (reviewed in [2]). Subunit II has been shown by cross-linking to ensure the docking of ferredoxin to subunit VII [3], Subunit III appeared to be necessary for the electron transfer from PCy to PS I [1]. This subunit does not carry a prosthetic group [4] and it is positively charged [5]. Its attribution to a band in SDS-PAGE is ambiguous because subunit III and IV alter their relative position in different gel systems [6]. Subunit III has been suggested to be identical with a subunit of 21 kDa [7] or a positively charged subunit of 9.7 kDa as deduced from the gene sequence [8]. Several authors have questioned a role of subunit III. However, in a recent study [9] PCy was cross-linked to a PS I subunit of 19 kDa. The function of this subunit and the assignment to one of the PS I subunits remains to be established.

Keywords

Methyl Viologen Primary Electron Donor Stroma Lamella Negative Surface Charge Density Peptide Deduce Sequence 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1990

Authors and Affiliations

  • Michael Hippler
    • 1
  • Rafael Ratajczak
    • 1
  • Wolfgang Haehnel
    • 1
  1. 1.Lehrstuhl für Biochemie der Pflanzen, Lehrstuhl für Medizinische CytologieUniversity of MünsterMünsterFederal Republic of Germany

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