אסיף מאגר המחקר החקלאי

The architecture of Rhodobacter sphaeroides chromatophores

Year:

2014

Source of publication :

Authors :

Volume :

1837

Co-Authors:

Scheuring, S., U1006 INSERM, Aix-Marseille Université, Parc Scientifique de Luminy, Marseille F-13009, France
Nevo, R., Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
Liu, L.-N., U1006 INSERM, Aix-Marseille Université, Parc Scientifique de Luminy, Marseille F-13009, France, Institute of Integrative Biology, Bioscience Building, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom
Mangenot, S., UMR168, CNRS, Institut Curie, 26 rue d'Ulm, 75005 Paris, France
Charuvi, D., Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
Boudier, T., Sorbonne Universités, UPMC Univ Paris 06, IBPS, F-75005 Paris, France
Prima, V., LISM, CNRS, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille, France
Hubert, P., LISM, CNRS, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille, France
Sturgis, J.N., LISM, CNRS, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille, France
Reich, Z., Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel

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Abstract:

The chromatophores of Rhodobacter (Rb.) sphaeroides represent a minimal bio-energetic system, which efficiently converts light energy into usable chemical energy. Despite extensive studies, several issues pertaining to the morphology and molecular architecture of this elemental energy conversion system remain controversial or unknown. To tackle these issues, we combined electron microscope tomography, immuno-electron microscopy and atomic force microscopy. We found that the intracellular Rb. sphaeroides chromatophores form a continuous reticulum rather than existing as discrete vesicles. We also found that the cytochrome bc1 complex localizes to fragile chromatophore regions, which most likely constitute the tubular structures that interconnect the vesicles in the reticulum. In contrast, the peripheral light-harvesting complex 2 (LH2) is preferentially hexagonally packed within the convex vesicular regions of the membrane network. Based on these observations, we propose that the bc1 complexes are in the inter-vesicular regions and surrounded by reaction center (RC) core complexes, which in turn are bounded by arrays of peripheral antenna complexes. This arrangement affords rapid cycling of electrons between the core and bc1 complexes while maintaining efficient excitation energy transfer from LH2 domains to the RCs. © 2014 Elsevier B.V.

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