Energy transfers in the B808-866 antenna from the green bacterium Chloroflexus aurantiacus.
Energy transfers within the B808-866 BChl a antenna in chlorosome-membrane complexes from the green photosynthetic bacterium Chloroflexus aurantiacus were studied in two-color pump-probe experiments at room temperature. The steady-state spectroscopy and protein sequence of the B808-866 complex are reminiscent of well-studied LH2 antennas from purple bacteria. B808-->B866 energy transfers occur with approximately 2 ps kinetics; this is slower by a factor of approximately 2 than B800-->B850 energy transfers in LH2 complexes from Rhodopseudomonas acidophila or Rhodobacter sphaeroides. Anisotropy studies show no evidence for intra-B808 energy transfers before the B808-->B866 step; intra-B866 processes are reflected in 350-550 fs anisotropy decays. Two-color anisotropies under 808 nm excitation suggest the presence of a B808-->B866 channel arising either from direct laser excitation of upper B866 exciton components that overlap the B808 absorption band or from excitation of B866 vibronic bands in nontotally symmetric modes.
Novoderezhkin
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A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia.
Taisova
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AS
Fetisova
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ZG
Blankenship
R E
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Savikhin
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S
Buck
D R
DR
Struve
W S
WS
D016880:Anisotropy; D001426:Bacterial Proteins / Q000737:chemistry*; D001429:Bacteriochlorophylls / Q000737:chemistry*; D055592:Biophysical Phenomena; D001703:Biophysics; D019414:Chlorobi / Q000737:chemistry*; D004735:Energy Transfer; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*
C081521:B800-850 light-harvesting complex, bacteria; D001426:Bacterial Proteins; D001429:Bacteriochlorophylls; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins