Redox effects on the bacteriochlorophyll α-containing Fenna-Matthews-Olson protein from Chlorobium tepidum

Wenli Zhou, Russell LoBrutto, Su Lin, Robert E. Blankenship

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

The BChl a-containing Fenna-Matthews-Olson (FMO) protein from the green sulfur bacterium Chlorobium tepidum was purified and characterized. Fluorescence spectra indicate that efficient excited state quenching occurs at neutral or oxidizing redox potentials. The major fluorescence lifetime at room temperature is approximately 60 ps in samples that are in neutral or oxidizing conditions, and approximately 2 ns in samples where the strong reductant sodium dithionite has been added. A similar change is observed in pump-probe picosecond absorbance difference experiments, where the long life time component increases after dithionite addition. A 16 Gauss wide EPR signal with g factor =2.005 is observed in samples without dithionite. This signal largely disappears upon addition of dithionite. Dithionite induces large reversibile changes in the 77 K absorbance spectra of the purified FMO protein and in whole cells. These results indicate that the FMO protein contains redox active groups, which may be involved in the regulation of energy transfer. Room temperature circular dichroism and low temperature absorption spectra show that dithionite also induces conformational or structural changes of the FMO protein complex.

Original languageEnglish (US)
Pages (from-to)89-96
Number of pages8
JournalPhotosynthesis research
Volume41
Issue number1
DOIs
StatePublished - Jul 1 1994

Keywords

  • Chlorobium tepidum
  • antenna
  • bacteriochlorophyll a protein
  • chlorosome
  • energy transfer
  • green bacteria
  • photosynthesis

ASJC Scopus subject areas

  • Biochemistry
  • Plant Science
  • Cell Biology

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