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 660 nm (originating from phycobilisomes) and at 681 nm (which, upon 440 nm excitation originates mostly from chlorophyll) was quenched. However, no blue-light-induced changes in the fluorescence yield were observed in the apcE- 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.
Original language | English (US) |
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Pages (from-to) | 757-765 |
Number of pages | 9 |
Journal | Biochimica et Biophysica Acta - Bioenergetics |
Volume | 1767 |
Issue number | 6 |
DOIs | |
State | Published - Jun 2007 |
Keywords
- Allophycocyanin
- Carotenoid
- Fluorescence quenching
- IsiA protein
- Photosystem II
- Phycobilisome
ASJC Scopus subject areas
- Biophysics
- Biochemistry
- Cell Biology