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Photosystem I at 4 Å resolution represents the first structural model of a joint photosynthetic reaction centre and core antenna system

Nature Structural Biologyvolume 3pages965973 (1996) | Download Citation



The 4 Å X-ray structure model of trimeric photosystem I of the cyanobacterium Synechococcus elongatus reveals 31 transmembrane, nine surface and three stromal α-helices per monomer, assigned to the 11 protein subunits: PsaA and PsaB are related by a pseudo two-fold axis normal to the membrane plane, along which the electron transfer pigments are arranged. 65 antenna chlorophyll a (Chl a) molecules separated by ≤16 Å form an oval, clustered net, continuous with the electron transfer chain through the second and third Chl a pairs of the electron transfer system. This suggests a dual role for these Chl a both in excitation energy and electron transfer. The architecture of the protein core indicates quinone and iron-sulphur type reaction centres to have a common ancestor.

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  1. Institut für Kristallographie, Freie Universität Berlin, Takustr. 6, 0-14195, Berlin, Germany

    • Norbert Krauß
    • , Wolf-Dieter Schubert
    • , Olaf Klukas
    •  & Wolfram Saenger
  2. Max-Volmer-lnstitut für biophysikalische Chemie und Biochemie, Technische Universität Berlin, Straße-des-17.Juni 135, D-10623, Berlin, Germany

    • Petra Fromme
    •  & Horst Tobias Witt


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