title: Pigment-protein architecture in the light-harvesting antenna complexes of purple bacteria: does the crystal structure reflect the native pigment-protein arrangement?
abstract: Structural analysis of crystallized peripheral (LH2) and core antenna complexes (LH1) of purple bacteria has revealed circular aggregates of high rotational symmetry (C8, C9 and C16, respectively). Quantum-chemical calculations indicate that in particular the waterwheel-like arrangements of pigments should show characteristic structure-sensitive spectroscopic behavior in the near infrared absorption region. Laser-spectroscopic data obtained with non-crystallized, isolated LH2 of Rhodospirillum molischianum are in line with a highly symmetric (C8) circular aggregate, but deviations have been found for LH2 of Rhodobacter sphaeroides and Rhodopseudomonas acidophila. For both the latter, C-shaped incomplete circular aggregates (as seen only recently in electron micrographs of crystallized LH1-reaction center complexes) may be a suitable preliminary model.
authors.affiliation: Max-Born-Institute for Non-linear Optics and Short Pulse Spectroscopy, Berlin, Germany. leupold@mbi-berlin.de
authors.forename: D
authors.initials: D
authors.lastname: Leupold
authors.forename: B
authors.initials: B
authors.lastname: Voigt
authors.forename: W
authors.initials: W
authors.lastname: Beenken
authors.forename: H
authors.initials: H
authors.lastname: Stiel
mesh_terms: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D010860:Pigments, Biological / Q000737:chemistry*; D011487:Protein Conformation; D012241:Rhodopseudomonas / Q000737:chemistry*; D012246:Rhodospirillum / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared / Q000379:methods
chemical_list: C081521:B800-850 light-harvesting complex, bacteria; D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D010860:Pigments, Biological; C094744:light-harvesting complex 1, Rhodospirillum