Nanodissection and high-resolution imaging of the Rhodopseudomonas viridis photosynthetic core complex in native membranes by AFM. Atomic force microscopy.
In photosynthesis, highly organized multiprotein assemblies convert sunlight into biochemical energy with high efficiency. A challenge in structural biology is to analyze such supramolecular complexes in native membranes. Atomic force microscopy (AFM) with high lateral resolution, high signal-to-noise ratio, and the possibility to nanodissect biological samples is a unique tool to investigate multiprotein complexes at molecular resolution in situ. Here we present high-resolution AFM of the photosynthetic core complex in native Rhodopseudomonas viridis membranes. Topographs at 10-A lateral and approximately 1-A vertical resolution reveal a single reaction center (RC) surrounded by a closed ellipsoid of 16 light-harvesting (LH1) subunits. Nanodissection of the tetraheme cytochrome (4Hcyt) subunit from the RC allows demonstration that the L and M subunits exhibit an asymmetric topography intimately associated to the LH1 subunits located at the short ellipsis axis. This architecture implies a distance distribution between the antenna and the RC compared with a centered location of the RC within a circular LH1, which may influence the energy transfer within the core complex. The LH1 subunits rearrange into a circle after removal of the RC from the core complex.
Scheuring
Simon
S
Institut Curie, Unité Mixte de Recherche-Centre National de la Recherche Scientifique 168 and Laboratoire de Recherche Correspondant-Commissariat à l'Energie Atomique 34V, 11 Rue Pierre et Marie Curie, 75231 Paris Cedex 05, France. simon.scheuring@curie.fr
Seguin
Jérôme
J
Marco
Sergio
S
Lévy
Daniel
D
Robert
Bruno
B
Rigaud
Jean-Louis
JL
D007091:Image Processing, Computer-Assisted; D018625:Microscopy, Atomic Force; D036103:Nanotechnology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000648:ultrastructure*; D012241:Rhodopseudomonas / Q000378:metabolism* / Q000648:ultrastructure
D045322:Photosynthetic Reaction Center Complex Proteins