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

Norbert Krauß, Wolf Dieter Schubert, Olaf Klukas, Petra Fromme, Horst Tobias Witt, Wolfram Saenger

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304 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)965-973
Number of pages9
JournalNature Structural Biology
Issue number11
StatePublished - Nov 1 1996
Externally publishedYes


ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Genetics

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