title: Polyamines stimulate non-photochemical quenching of chlorophyll a fluorescence in Scenedesmus obliquus.
abstract: Polyamines (PAs) are small metabolites that are produced and oxidized in chloroplasts with an obscure mode of action. Recently, we showed that qE is stimulated by PAs in higher plants (Nicotiana tabacum) and in genetically modified plants with elevated thylakoid-associated PAs (Ioannidis and Kotzabasis Biochim Biophys Acta 1767:1371-1382, 2007; Ioannidis et al. Biochim Biophys Acta 1787:1215-1222, 2009). Here, we investigated further their quenching properties both in vivo in green algae and in vitro is isolated LHCII. In vivo spermine up-regulates NPQ in Scenedesums obliquus about 30%. In vitro putrescine--the obligatory metabolic precursor of PAs--has a marginal quenching effect, while spermidine and spermine exhibit strong quenching abilities in isolated LHCII up to 40%. Based on available 3D models of LHCII we report a special cavity of about 600 Å(3) and a near-by larger pocket in the trimeric LHCII that could be of importance for the stimulation of qE by amines.
authors.affiliation: Department of Biology, University of Crete, P.O. Box 2208, 71409 Heraklion, Crete, Greece.
authors.forename: Nikolaos E
authors.initials: NE
authors.lastname: Ioannidis
authors.forename: Liliana
authors.initials: L
authors.lastname: Sfichi-Duke
authors.forename: Kiriakos
authors.initials: K
authors.lastname: Kotzabasis
mesh_terms: D015317:Biogenic Polyamines / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism*; D000077194:Chlorophyll A; D005453:Fluorescence; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D017434:Protein Structure, Tertiary; D044444:Scenedesmus / Q000378:metabolism*; D013095:Spermidine / Q000378:metabolism / Q000502:physiology; D013096:Spermine / Q000378:metabolism / Q000502:physiology
chemical_list: D015317:Biogenic Polyamines; D045342:Light-Harvesting Protein Complexes; D010940:Plant Proteins; D002734:Chlorophyll; D013096:Spermine; D013095:Spermidine; D000077194:Chlorophyll A