PsbS enhances nonphotochemical fluorescence quenching in the absence of zeaxanthin.
Leaves and chloroplasts from Arabidopsis plants with increased amounts of PsbS protein showed the same percentage increase in nonphotochemical quenching in comparison to the wild type both in the presence and absence of zeaxanthin. The absorption change at 525-535 nm was also more pronounced in both cases. It is suggested that PsbS alone can cause the quenching, supporting the model in which zeaxanthin acts as an allosteric activator and is not the primary cause of the process. It is proposed that PsbS acts as a trigger of the conformational change that leads to the establishment of nonphotochemical quenching.
Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
Sophie
S
Crouchman
Alexander
A
Ruban
Peter
P
Horton
D000585:Aminacrine; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D005453:Fluorescence; D015870:Gene Expression; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes; D010777:Photochemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D013997:Time Factors; D024341:Xanthophylls / Q000172:deficiency* / Q000378:metabolism*; D065146:Zeaxanthins
D029681:Arabidopsis Proteins; D045342:Light-Harvesting Protein Complexes; C489731:NPQ4 protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D024341:Xanthophylls; D065146:Zeaxanthins; D000585:Aminacrine