Architecture of a charge-transfer state regulating light harvesting in a plant antenna protein.
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.
Ahn
Tae Kyu
TK
Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Avenson
Thomas J
TJ
Ballottari
Matteo
M
Cheng
Yuan-Chung
YC
Niyogi
Krishna K
KK
Bassi
Roberto
R
Fleming
Graham R
GR
D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002734:Chlorophyll / Q000502:physiology; D000077194:Chlorophyll A; D061146:Chlorophyll Binding Proteins; D060365:Chloroplast Proteins; D004579:Electron Transport; D004594:Electrophysiology; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D014975:Lutein / Q000378:metabolism; D008958:Models, Molecular; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000378:metabolism; D012261:Ribonucleoproteins; D013329:Structure-Activity Relationship; D024341:Xanthophylls / Q000378:metabolism; D065146:Zeaxanthins
D029681:Arabidopsis Proteins; D061146:Chlorophyll Binding Proteins; D060365:Chloroplast Proteins; C490432:LHCB5 protein, Arabidopsis; D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; C529074:RBP29 protein, Arabidopsis; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D024341:Xanthophylls; D065146:Zeaxanthins; D002734:Chlorophyll; C005613:violaxanthin; C037184:chlorophyll b; D014975:Lutein; D000077194:Chlorophyll A