Energy transfer kinetics in whole cells and isolated chlorosomes of green photosynthetic bacteria

Timothy P. Causgrove, Daniel C. Brune, Jian Wang, Bruce Paul Wittmershaus, Robert E. Blankenship

Research output: Contribution to journalArticle

54 Scopus citations

Abstract

Time-resolved fluorescence spectroscopy and global data analysis techniques have been used to study the flow of excitations in antennae of the green photosynthetic bacteria Chloroflexus aurantiacus and Chlorobium vibrioforme f. thiosulfatophilum. The transfer of energy from bacteriochlorophyll (BChl) c in Chloroflexus or BChl d in Chlorobium to BChl a795 was resolved in both whole cells and isolated chlorosomes. In Chloroflexus, the decay of excitations in BChl c occurs in ∼16 ps and a corresponding rise in BChl a emission at 805 nm is detected in global analyses. This band then decays in 46 ps in whole cells due to energy transfer into the membrane. The 805 nm fluorescence in isolated chlorosomes shows a fast decay component similar to that of whole cells, which is consistent with trapping by residual membrane antenna complexes. In Chlorobium, the kinetics are sensitive to the presence of oxygen. Under anaerobic conditions, BChl d decays in 66 ps while the lifetime shortens to 11 ps in aerobic samples. The effect is reversible and occurs in both whole cells and isolated chlorosomes. Emission from BChl a is similarly affected by oxygen, indicating that oxidant-induced quenching can occur from all chlorosome pigments.

Original languageEnglish (US)
Pages (from-to)39-48
Number of pages10
JournalPhotosynthesis research
Volume26
Issue number1
DOIs
StatePublished - Oct 1 1990

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Plant Science
  • Cell Biology

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