Chlorophyll fluorescence quenching in isolated light harvesting complexes induced by zeaxanthin

Abstract 

Non-photochemical quenching of chlorophyll fluorescence in plants occurs in the light harvesting antenna of photosystem II and is regulated by the xanthophyll cycle. A new in vitro model for this process has been developed. Purified light harvesting complexes above the detergent critical micelle concentration have a stable high fluorescence yield but a rapidly inducible fluorescence quenching occurs upon addition of zeaxanthin. Violaxanthin was without effect, lutein and antheraxanthin induced a marginal response, whereas the violaxanthin analogue, auroxanthin, induced strong quenching. Quenching was not caused by aggregation of the complexes but was accompanied by a spectral broadening and red shift, indicating a zeaxanthin-dependent alteration in the chlorophyll environment.

Keywords:  Non-photochemical quenching, Light harvesting complex, Xanthophyll cycle, Chlorophyll fluorescence, Thylakoid membrane

Abbreviations:  DBMIB, 2,5-dibromo-3-methyl-6-isopropyl-ρ-benzoquinone, DM, n-dodecyl β-maltoside, Lhcb, proteins encoded by the Lhcb genes, LHC II, the light harvesting complexes of photosystem II, NPQ, non-photochemical quenching, PS II, photosystem II, qE, non-photochemical quenching dependent upon the ΔpH, ΔpH, transthylakoid pH gradient