TY - JOUR
T1 - Light-induced isomerization of the LHCII-bound xanthophyll neoxanthin
T2 - Possible implications for photoprotection in plants
AU - Zubik, Monika
AU - Luchowski, Rafał
AU - Grudzinski, Wojciech
AU - Gospodarek, Małgorzata
AU - Gryczynski, Ignacy
AU - Gryczynski, Zygmunt
AU - Dobrucki, Jerzy W.
AU - Gruszecki, Wiesław I.
N1 - Funding Information:
The authors wish to thank Prof. Stanislaw Krawczyk for making available the Stark effect experimental set-up and expertise advices. This research was financed by the Ministry of Science and Higher Education of Poland from the funds for science in the years 2008–2011 within the research project N N303 285034. ZG acknowledges the financial support from NIH ( R01EB012003 ).
PY - 2011/9
Y1 - 2011/9
N2 - Light-harvesting pigment-protein complex of Photosystem II (LHCII) is the largest photosynthetic antenna complex of plants and the most abundant membrane protein in the biosphere. Plant fitness and productivity depend directly on a balance between excitations in the photosynthetic apparatus, generated by captured light quanta, and the rate of photochemical processes. Excess excitation energy leads to oxidative damage of the photosynthetic apparatus and entire organism and therefore the balance between the excitation density and photosynthesis requires precise and efficient regulation, operating also at the level of antenna complexes. We show that illumination of the isolated LHCII leads to isomerization of the protein-bound neoxanthin from conformation 9′-cis to 9′,13- and 9′,13′-dicis forms. At the same time light-driven excitation quenching is observed, manifested by a decrease in chlorophyll a fluorescence intensity and shortened fluorescence lifetimes. Both processes, the neoxanthin isomerization and the chlorophyll excitation quenching, are reversible in dim light. The results of the 77 K florescence measurements of LHCII show that illumination is associated with appearance of the low-energy states, which can serve as energy traps in the pigment-protein complex subjected to excess excitation. Possible sequence of the molecular events is proposed, leading to a protective excess excitation energy quenching: neoxanthin photo-isomerization → formation of LHCII supramolecular structures which potentiate creation of energy traps → excitation quenching.
AB - Light-harvesting pigment-protein complex of Photosystem II (LHCII) is the largest photosynthetic antenna complex of plants and the most abundant membrane protein in the biosphere. Plant fitness and productivity depend directly on a balance between excitations in the photosynthetic apparatus, generated by captured light quanta, and the rate of photochemical processes. Excess excitation energy leads to oxidative damage of the photosynthetic apparatus and entire organism and therefore the balance between the excitation density and photosynthesis requires precise and efficient regulation, operating also at the level of antenna complexes. We show that illumination of the isolated LHCII leads to isomerization of the protein-bound neoxanthin from conformation 9′-cis to 9′,13- and 9′,13′-dicis forms. At the same time light-driven excitation quenching is observed, manifested by a decrease in chlorophyll a fluorescence intensity and shortened fluorescence lifetimes. Both processes, the neoxanthin isomerization and the chlorophyll excitation quenching, are reversible in dim light. The results of the 77 K florescence measurements of LHCII show that illumination is associated with appearance of the low-energy states, which can serve as energy traps in the pigment-protein complex subjected to excess excitation. Possible sequence of the molecular events is proposed, leading to a protective excess excitation energy quenching: neoxanthin photo-isomerization → formation of LHCII supramolecular structures which potentiate creation of energy traps → excitation quenching.
KW - Fluorescence
KW - LHCII
KW - Photoprotection
KW - Photosynthesis
KW - Spectroscopy
KW - Xanthophyll
UR - http://www.scopus.com/inward/record.url?scp=79960565713&partnerID=8YFLogxK
U2 - 10.1016/j.bbabio.2011.06.011
DO - 10.1016/j.bbabio.2011.06.011
M3 - Article
C2 - 21718685
AN - SCOPUS:79960565713
SN - 0005-2728
VL - 1807
SP - 1237
EP - 1243
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
IS - 9
ER -