title: Comparative study of spectral flexibilities of bacterial light-harvesting complexes: structural implications.
abstract: This work presents a comparative study of the frequencies of spectral jumping of individual light-harvesting complexes of six different types: LH2 of Rhodopseudomonas acidophila, Rhodobacter sphaeroides, and Rhodospirillum molischianum; LH1 of Rhodobacter sphaeroides; and two "domain swap mutants" of LH2 of Rhodobacter sphaeroides: PACLH1 and PACLH2mol, in which the alpha-polypeptide C-terminus is exchanged with the corresponding sequence from LH1 of Rhodobacter sphaeroides or LH2 of Rhodospirillum molischianum, respectively. The quasistable states of fluorescence peak wavelength that were previously observed for the LH2 of Rps. acidophila were confirmed for other species. We also observed occurrences of extremely blue-shifted spectra, which were associated with reversible bleaching of one of the chromophore rings. Different jumping behavior is observed for single complexes of different types investigated with the same equivalent excitation intensity. The differences in spectral diffusion are associated with subtle differences of the binding pocket of B850 pigments and the structural flexibility of the different types of complexes.
authors.affiliation: Department of Biophysics and Physics of Complex Systems, Division of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands. danielis@nat.vu.nl
authors.forename: Danielis
authors.initials: D
authors.lastname: Rutkauskas
authors.forename: John
authors.initials: J
authors.lastname: Olsen
authors.forename: Andrew
authors.initials: A
authors.lastname: Gall
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cogdell
authors.forename: C Neil
authors.initials: CN
authors.lastname: Hunter
authors.forename: Rienk
authors.initials: R
authors.lastname: van Grondelle
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D001703:Biophysics / Q000379:methods*; D002244:Carbon / Q000737:chemistry; D006860:Hydrogen Bonding; D007477:Ions; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011522:Protons; D012242:Rhodobacter sphaeroides / Q000378:metabolism; D012241:Rhodopseudomonas / Q000378:metabolism*; D012246:Rhodospirillum / Q000378:metabolism*; D013045:Species Specificity; D013053:Spectrophotometry; D013696:Temperature; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D007477:Ions; D045342:Light-Harvesting Protein Complexes; D011522:Protons; D002244:Carbon; D008274:Magnesium