Open AccessArchitecture of a Charge-Transfer State Regulating Light Harvesting in a Plant Antenna Protein
Author(s) -
Tae Kyu Ahn,
Thomas J. Avenson,
Matteo Ballottari,
YuanChung Cheng,
Krishiyogi,
Roberto Bassi,
Graham R. Fleming
Publication year - 2008
Publication title -
science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 12.556
H-Index - 1186
eISSN - 1095-9203
pISSN - 0036-8075
DOI - 10.1126/science.1154800
Subject(s) - photochemistry , quenching (fluorescence) , photosystem ii , chlorophyll fluorescence , p700 , chemistry , electron transfer , photosynthesis , non photochemical quenching , zeaxanthin , chlorophyll , delocalized electron , light harvesting complex , excited state , photosystem i , fluorescence , atomic physics , physics , carotenoid , lutein , optics , biochemistry , organic chemistry
Energy-dependent quenching of excess absorbed light energy (qE) is a vital mechanism for regulating photosynthetic light harvesting in higher plants. All of the physiological characteristics of qE have been positively correlated with charge transfer between coupled chlorophyll and zeaxanthin molecules in the light-harvesting antenna of photosystem II (PSII). We found evidence for charge-transfer quenching in all three of the individual minor antenna complexes of PSII (CP29, CP26, and CP24), and we conclude that charge-transfer quenching in CP29 involves a delocalized state of an excitonically coupled chlorophyll dimer. We propose that reversible conformational changes in CP29 can "tune" the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of the chlorophyll-zeaxanthin charge-transfer state and switching on and off the charge-transfer quenching during qE.
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