title: Prediction of respective contribution of linear electron flow and PGR5-dependent cyclic electron flow to non-photochemical quenching induction.
abstract: In chloroplasts, regulated formation of the proton gradient across the thylakoid membrane (ΔpH) is important for controlling non-photochemical quenching (NPQ), which is crucial for plants to perform photosynthesis under fluctuating light conditions. The ΔpH is generated by two electron flows: the linear electron flow (LEF) and the cyclic electron flow (CEF). The Arabidopsis CEF mutant, pgr5, showed significantly lower NPQ values than those observed in WT, indicating that ΔpH, generated by the PGR5-dependent CEF, has a crucial role in controlling NPQ. However, the respective significance of LEF and CEF for ΔpH formation is largely unknown. Here we applied computer simulation to reproduce NPQ induction kinetics and estimate the respective contribution of LEF and PGR5-dependent CEF to the dynamics of ΔpH formation. The results indicate that the contribution of CEF to total ΔpH formation for induction of NPQ varies from 60-80%. The simulation also suggested a role of the PGR5-dependent CEF in accelerating electron transfer in the cytochrome b6f complex.
authors.affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Sato
authors.affiliation: Center for Biological Resources and Informatics, Tokyo Institute of Technology, Yokohama 226-8501, Japan; Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohta
authors.affiliation: Center for Biological Resources and Informatics, Tokyo Institute of Technology, Yokohama 226-8501, Japan; Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan. Electronic address: shmasuda@bio.titech.ac.jp.
authors.forename: Shinji
authors.initials: S
authors.lastname: Masuda
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D003198:Computer Simulation; D004579:Electron Transport; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D008954:Models, Biological; D009154:Mutation; D010084:Oxidation-Reduction; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C465062:PGR5 protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D002734:Chlorophyll
keywords: Chlorophyll fluorescence; Cyclic electron flow; NPQ induction; PGR5; Regulation of photosynthesis