Carotenoid-triggered energy dissipation in phycobilisomes of Synechocystis sp. PCC 6803 diverts excitation away from reaction centers of both photosystems

Marina G. Rakhimberdieva, Irina V. Elanskaya, Willem Vermaas, Navassard V. Karapetyan

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

Cyanobacteria are capable of using dissipation of phycobilisome-absorbed energy into heat as part of their photoprotective strategy. Non-photochemical quenching in cyanobacteria cells is triggered by absorption of blue-green light by the carotenoid-binding protein, and involves quenching of phycobilisome fluorescence. In this study, we find direct evidence that the quenching is accompanied by a considerable reduction of energy flow to the photosystems. We present light saturation curves of photosystems' activity in quenched and non-quenched states in the cyanobacterium Synechocystis sp. PCC 6803. In the quenched state, the quantum efficiency of light absorbed by phycobilisomes drops by about 30-40% for both photoreactions-P700 photooxidation in the photosystem II-less strain and photosystem II fluorescence induction in the photosystem I-less strain of Synechocystis. A similar decrease of the excitation pressure on both photosystems leads us to believe that the core-membrane linker allophycocyanin APC-LCM is at or beyond the point of non-photochemical quenching. We analyze 77 K fluorescence spectra and suggest that the quenching center is formed at the level of the short-wavelength allophycocyanin trimers. It seems that both chlorophyll and APC-LCM may dissipate excess energy via uphill energy transfer at physiological temperatures, but neither of the two is at the heart of the carotenoid-binding protein-dependent non-photochemical quenching mechanism.

Original languageEnglish (US)
Pages (from-to)241-249
Number of pages9
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1797
Issue number2
DOIs
StatePublished - Feb 1 2010

Keywords

  • Allophycocyanin
  • Cyanobacteria
  • Energy dissipation
  • Fluorescence quenching
  • Photosystem

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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