Supramolecular organization of phycobiliproteins in the chlorophyll d-containing cyanobacterium Acaryochloris marina

Here we report the high-resolution detail of the organization of phycobiliprotein structures associated with photosynthetic membranes of the chlorophyll d-containing cyanobacterium Acaryochloris marina. Cryo-electron transmission-microscopy on native cell sections show extensive patches of near-crystalline phycobiliprotein rods that are associated with the stromal side of photosynthetic membranes. This supramolecular photosynthetic structure represents a novel mechanism of organizing the photosynthetic light-harvesting machinery. In addition, the specific location of phycobiliprotein patches suggests a physical separation of photosystem I and photosystem II reaction centres. Based on this finding and the known photosystem's structure in Acaryochloris, we discuss possible membrane arrangements of photosynthetic membrane complexes in this species. (c) 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.