title: Activation of zeaxanthin is an obligatory event in the regulation of photosynthetic light harvesting.
abstract: By dynamic changes in protein structure and function, the photosynthetic membranes of plants are able to regulate the partitioning of absorbed light energy between utilization in photosynthesis and photoprotective non-radiative dissipation of the excess energy. This process is controlled by features of the intact membrane, the transmembrane pH gradient, the organization of the photosystem II antenna proteins and the reversible binding of a specific carotenoid, zeaxanthin. Resonance Raman spectroscopy has been applied for the first time to wild type and mutant Arabidopsis leaves and to intact thylakoid membranes to investigate the nature of the absorption changes obligatorily associated with the energy dissipation process. The observed changes in the carotenoid Resonance Raman spectrum proved that zeaxanthin was involved and indicated a dramatic change in zeaxanthin environment that specifically alters the pigment configuration and red-shifts the absorption spectrum. This activation of zeaxanthin is a key event in the regulation of light harvesting.
authors.affiliation: Robert Hill Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom. a.ruban@sheffield.ac.uk
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Ruban
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Pascal
authors.forename: Bruno
authors.initials: B
authors.lastname: Robert
authors.forename: Peter
authors.initials: P
authors.lastname: Horton
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D002734:Chlorophyll / Q000737:chemistry; D002736:Chloroplasts / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D008027:Light; D008055:Lipids / Q000737:chemistry; D008823:Micelles; D010788:Photosynthesis; D011487:Protein Conformation; D011725:Pyridines / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D013997:Time Factors; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene / Q000031:analogs & derivatives / Q000737:chemistry* / Q000378:metabolism
chemical_list: D008055:Lipids; D008823:Micelles; D011725:Pyridines; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D002734:Chlorophyll; C023666:pyridine