Structure and functional role of supercomplexes of IsiA and Photosystem I in cyanobacterial photosynthesis

Roman Kouřil, Ana A. Arteni, Julia Lax, Nataliya Yeremenko, Sandrine D' Haene, Matthias Rögner, Hans C.P. Matthijs, Jan P. Dekker, Egbert J. Boekema

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Cyanobacteria express large quantities of the iron stress-inducible protein IsiA under iron deficiency. IsiA can assemble into numerous types of single or double rings surrounding Photosystem I. These supercomplexes are functional in light-harvesting, empty IsiA rings are effective energy dissipaters. Electron microscopy studies of these supercomplexes show that Photosystem I trimers bind 18 IsiA copies in a single ring, whereas monomers may bind up to 35 copies in two rings. Work on mutants indicates that the PsaF/J and PsaL subunits facilitate the formation of closed rings around Photosystem I monomers but are not obligatory components in the formation of Photosystem I–IsiA supercomplexes.
Original languageEnglish
Pages (from-to)3253 - 3257
Number of pages5
JournalFEBS Letters
Issue number15
Publication statusPublished - 2005


  • Electron microscopy
  • PsaL
  • PsaF/J
  • IsiA
  • Photosystem I

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