Isolation and characterization of the B798 light-harvesting baseplate from the chlorosomes of Chloroflexus aurantiacus

Biochemistry. 2003 Sep 2;42(34):10246-51. doi: 10.1021/bi034350k.


The B798 light-harvesting baseplate of the chlorosome antenna complex of the thermophilic, filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus has been isolated and characterized. Isolation was performed by using a hexanol-detergent treatment of freeze-thawed chlorosomes. The isolated baseplate consists of Bchl a, beta-carotene, and the 5.7 kDa CsmA protein with a ratio of 1.0 CsmA protein/1.6 Bchl a/4.2 beta-carotenes. The baseplate has characteristic absorbance at 798 nm as well as carotenoid absorbance maxima at 519, 489, and 462 nm. The energy transfer efficiency from the carotenoids to the Bchl a is 30% as measured by steady-state and ultrafast time-resolved fluorescence and absorption spectroscopies. Energy equilibration within the Bchl a absorbing regions exhibits ultrafast kinetics. Circular dichroism spectroscopy shows no evidence for excitonically coupled Bchl a pools within the 798 nm region.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / isolation & purification
  • Bacteriochlorophylls / chemistry
  • Bacteriochlorophylls / isolation & purification
  • Chlorobi / chemistry*
  • Chromosomes / chemistry*
  • Electrophoresis, Polyacrylamide Gel
  • Energy Transfer
  • Kinetics
  • Light-Harvesting Protein Complexes
  • Photosynthetic Reaction Center Complex Proteins / chemistry*
  • Photosynthetic Reaction Center Complex Proteins / isolation & purification*
  • Spectrum Analysis / methods
  • beta Carotene / chemistry
  • beta Carotene / isolation & purification


  • Bacterial Proteins
  • Bacteriochlorophylls
  • CsmM protein, Chloroflexus aurantiacus
  • Light-Harvesting Protein Complexes
  • Photosynthetic Reaction Center Complex Proteins
  • beta Carotene