title: The long-range supraorganization of the bacterial photosynthetic unit: A key role for PufX.
abstract: Bacterial photosynthesis relies on the interplay between light harvesting and electron transfer complexes, all of which are located within the intracytoplasmic membrane. These complexes capture and transfer solar energy, which is used to generate a proton gradient. In this study, we identify one of the factors that determines the organization of these complexes. We undertook a comparison of the organization of the light-harvesting complex 1 (LH1)/reaction center (RC) cores in the LH2(-) mutant of Rhodobacter sphaeroides in the presence or absence of the PufX protein. From polarized absorption spectra on oriented membranes, we conclude that PufX induces a specific orientation of the reaction center in the LH1 ring, as well as the formation of a long-range regular array of LH1-RC cores in the photosynthetic membrane. From our data, we have constructed a precise model of how the RC is positioned within the LH1 ring relative to the long (orientation) axis of the photosynthetic membrane.
authors.affiliation: Department of Physics and Astronomy and Institute for Molecular Biological Sciences, Vrije Universiteit, De Boelelaan 1081, 1081HV Amsterdam, The Netherlands. raoul@nat.vu.nl
authors.forename: R N
authors.initials: RN
authors.lastname: Frese
authors.forename: J D
authors.initials: JD
authors.lastname: Olsen
authors.forename: R
authors.initials: R
authors.lastname: Branvall
authors.forename: W H
authors.initials: WH
authors.lastname: Westerhuis
authors.forename: C N
authors.initials: CN
authors.lastname: Hunter
authors.forename: R
authors.initials: R
authors.lastname: van Grondelle
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D003624:Darkness; D008027:Light; D045342:Light-Harvesting Protein Complexes; D046911:Macromolecular Substances; D008958:Models, Molecular; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D012242:Rhodobacter sphaeroides / Q000235:genetics / Q000378:metabolism*; D013053:Spectrophotometry
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D046911:Macromolecular Substances; D045322:Photosynthetic Reaction Center Complex Proteins; C088749:PufX protein, Rhodobacter