A new carotenoid-to-BChl energy transfer pathway in photosynthetic light harvesting

Abstract

Carotenoids play an important role in photosynthetic light harvesting and photoprotection. We have recently demonstrated that upon excitation of the carotenoid spirilloxanthin bound to the light harvesting complex of the purple photosynthetic bacterium Rs. rubrum, spirilloxanthin triplet states are generated with a high yield on a femtosecond to picosecond timescale (C.C. Gradinaru et al., (2001) Proc. Natl. Acad. Sci. (USA), 98, 2364-2369.). To obtain a better understanding of this surprising phenomenon, we have extended our studies to light harvesting complexes of different species of purple bacteria, and have performed a systematic study of the dynamic behavior of a range of carotenoids artificially incorporated into the LH complexes of the photosynthetic bacteria Rs. rubrum and Rhodobacter sphaeroides.