title: The Lhcb protein and xanthophyll composition of the light harvesting antenna controls the DeltapH-dependency of non-photochemical quenching in Arabidopsis thaliana.
abstract: Nonphotochemical quenching (NPQ) is the photoprotective dissipation of energy in photosynthetic membranes. The hypothesis that the DeltapH-dependent component of NPQ (qE) component of non-photochemical quenching is controlled allosterically by the xanthophyll cycle has been tested using Arabidopsis mutants with different xanthophyll content and composition of Lhcb proteins. The titration curves of qE against DeltapH were different in chloroplasts containing zeaxanthin or violaxanthin, proving their roles as allosteric activator and inhibitor, respectively. The curves differed in mutants deficient in lutein and specific Lhcb proteins. The results show that qE is determined by xanthophyll occupancy and the structural interactions within the antenna that govern allostericity.
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Pérez-Bueno
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Johnson
authors.forename: Ahmad
authors.initials: A
authors.lastname: Zia
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Ruban
authors.forename: Peter
authors.initials: P
authors.lastname: Horton
mesh_terms: D000494:Allosteric Regulation; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D061146:Chlorophyll Binding Proteins; D006863:Hydrogen-Ion Concentration; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010777:Photochemistry; D010788:Photosynthesis; D018892:Proton-Motive Force / Q000235:genetics; D024341:Xanthophylls / Q000032:analysis / Q000378:metabolism*; D065146:Zeaxanthins
chemical_list: D029681:Arabidopsis Proteins; D061146:Chlorophyll Binding Proteins; C529795:Lhcb6 protein, Arabidopsis; D045342:Light-Harvesting Protein Complexes; D024341:Xanthophylls; D065146:Zeaxanthins; C005613:violaxanthin