title: Thermo-optically induced reorganizations in the main light harvesting antenna of plants. I. Non-Arrhenius type of temperature dependence and linear light-intensity dependencies.
abstract: Thermo-optically induced structural reorganizations have earlier been identified in isolated LHCII, the main chlorophyll a/b light harvesting complexes of Photosystem II, and in granal thylakoid membranes [Cseh et al. (2000) Biochemistry 39: 15250-15257; Garab et al. (2002) Biochemistry 41: 15121-15129]. According to the thermo-optic mechanism, structural changes can be induced by fast, local thermal transients due to the dissipation of excess excitation energy. In this paper, we analyze the temperature and light-intensity dependencies of thermo-optically induced reversible and irreversible reorganizations in the chiral macrodomains of lamellar aggregates of isolated LHCII and of granal thylakoid membranes. We show that these structural changes exhibit non-Arrhenius type of temperature dependencies, which originate from the 'combination' of the ambient temperature and the local thermal transient. The experimental data can satisfactorily be simulated with the aid of a simple mathematical model based on the thermo-optic effect. The model also predicts, in good accordance with experimental data published earlier and presented in this paper, that the reorganizations depend linearly on the intensity of the excess light, a unique property that is probably important in light adaptation and photoprotection of plants.
authors.affiliation: Institute of Plant Biology, Hungarian Academy of Sciences, Szeged, P.O. Box 521, 6701 Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Cseh
authors.forename: Alberto
authors.initials: A
authors.lastname: Vianelli
authors.forename: Subramanyam
authors.initials: S
authors.lastname: Rajagopal
authors.forename: Sashka
authors.initials: S
authors.lastname: Krumova
authors.forename: László
authors.initials: L
authors.lastname: Kovács
authors.forename: Elemér
authors.initials: E
authors.lastname: Papp
authors.forename: Virginijus
authors.initials: V
authors.lastname: Barzda
authors.forename: Robert
authors.initials: R
authors.lastname: Jennings
authors.forename: Gyozo
authors.initials: G
authors.lastname: Garab
mesh_terms: D002942:Circular Dichroism; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects*; D018532:Pisum sativum / Q000737:chemistry*; D018724:Spinacia oleracea / Q000737:chemistry*; D013696:Temperature
chemical_list: D045342:Light-Harvesting Protein Complexes