title: Photoprotection in plants involves a change in lutein 1 binding domain in the major light-harvesting complex of photosystem II.
abstract: Nonphotochemical quenching (NPQ) is the fundamental process by which plants exposed to high light intensities dissipate the potentially harmful excess energy as heat. Recently, it has been shown that efficient energy dissipation can be induced in the major light-harvesting complexes of photosystem II (LHCII) in the absence of protein-protein interactions. Spectroscopic measurements on these samples (LHCII gels) in the quenched state revealed specific alterations in the absorption and circular dichroism bands assigned to neoxanthin and lutein 1 molecules. In this work, we investigate the changes in conformation of the pigments involved in NPQ using resonance Raman spectroscopy. By selective excitation we show that, as well as the twisting of neoxanthin that has been reported previously, the lutein 1 pigment also undergoes a significant change in conformation when LHCII switches to the energy dissipative state. Selective two-photon excitation of carotenoid (Car) dark states (Car S(1)) performed on LHCII gels shows that the extent of electronic interactions between Car S(1) and chlorophyll states correlates linearly with chlorophyll fluorescence quenching, as observed previously for isolated LHCII (aggregated versus trimeric) and whole plants (with versus without NPQ).
authors.affiliation: Commisariat à l'Energie Atomique, Institut de Biologie et Technologies de Saclay and CNRS URA 2096, F-91191 Gif sur Yvette, France. cristian.ilioaia@cea.fr
authors.forename: Cristian
authors.initials: C
authors.lastname: Ilioaia
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Johnson
authors.forename: Pen-Nan
authors.initials: PN
authors.lastname: Liao
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Pascal
authors.forename: Rienk
authors.initials: R
authors.lastname: van Grondelle
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Walla
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Ruban
authors.forename: Bruno
authors.initials: B
authors.lastname: Robert
mesh_terms: D017360:Arabidopsis / Q000378:metabolism / Q000502:physiology*; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D014975:Lutein / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D013059:Spectrum Analysis, Raman
chemical_list: D045332:Photosystem II Protein Complex; D014975:Lutein