Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1943584 | Biochimica et Biophysica Acta (BBA) - Bioenergetics | 2007 | 9 Pages |
Abstract
To determine the mechanism of carotenoid-sensitized non-photochemical quenching in cyanobacteria, the kinetics of blue-light-induced quenching and fluorescence spectra were studied in the wild type and mutants of Synechocystis sp. PCC 6803 grown with or without iron. The blue-light-induced quenching was observed in the wild type as well as in mutants lacking PS II or IsiA confirming that neither IsiA nor PS II is required for carotenoid-triggered fluorescence quenching. Both fluorescence at 660Â nm (originating from phycobilisomes) and at 681Â nm (which, upon 440Â nm excitation originates mostly from chlorophyll) was quenched. However, no blue-light-induced changes in the fluorescence yield were observed in the apcEâ mutant that lacks phycobilisome attachment. The results are interpreted to indicate that interaction of the Slr1963-associated carotenoid with - presumably - allophycocyanin in the phycobilisome core is responsible for non-photochemical energy quenching, and that excitations on chlorophyll in the thylakoid equilibrate sufficiently with excitations on allophycocyanin in wild type to contribute to quenching of chlorophyll fluorescence.
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Authors
Marina G. Rakhimberdieva, Dmitrii V. Vavilin, Wim F.J. Vermaas, Irina V. Elanskaya, Navassard V. Karapetyan,