title: Nanodissection and high-resolution imaging of the Rhodopseudomonas viridis photosynthetic core complex in native membranes by AFM. Atomic force microscopy.
abstract: 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.
authors.affiliation: 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
authors.forename: Simon
authors.initials: S
authors.lastname: Scheuring
authors.forename: Jérôme
authors.initials: J
authors.lastname: Seguin
authors.forename: Sergio
authors.initials: S
authors.lastname: Marco
authors.forename: Daniel
authors.initials: D
authors.lastname: Lévy
authors.forename: Bruno
authors.initials: B
authors.lastname: Robert
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Rigaud
mesh_terms: 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
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins