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

Gabriel A. Montaño, Hsing Mei Wu, Su Lin, Daniel C. Brune, Robert E. Blankenship

Research output: Contribution to journalArticle

59 Scopus citations

Abstract

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, β-carotene, and the 5.7 kDa CsmA protein with a ratio of 1.0 CsmA protein/1.6 Bchl a/4.2 β-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.

Original languageEnglish (US)
Pages (from-to)10246-10251
Number of pages6
JournalBiochemistry
Volume42
Issue number34
DOIs
StatePublished - Sep 2 2003

ASJC Scopus subject areas

  • Biochemistry

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