title: Effect of Chlamydomonas plastid terminal oxidase 1 expressed in tobacco on photosynthetic electron transfer.
abstract: The plastid terminal oxidase PTOX is a plastohydroquinone:oxygen oxidoreductase that is important for carotenoid biosynthesis and plastid development. Its role in photosynthesis is controversially discussed. Under a number of abiotic stress conditions, the protein level of PTOX increases. PTOX is thought to act as a safety valve under high light protecting the photosynthetic apparatus against photodamage. However, transformants with high PTOX level were reported to suffer from photoinhibition. To analyze the effect of PTOX on the photosynthetic electron transport, tobacco expressing PTOX-1 from Chlamydomonas reinhardtii (Cr-PTOX1) was studied by chlorophyll fluorescence, thermoluminescence, P700 absorption kinetics and CO2 assimilation. Cr-PTOX1 was shown to compete very efficiently with the photosynthetic electron transport for PQH2 . High pressure liquid chromatography (HPLC) analysis confirmed that the PQ pool was highly oxidized in the transformant. Immunoblots showed that, in the wild-type, PTOX was associated with the thylakoid membrane only at a relatively alkaline pH value while it was detached from the membrane at neutral pH. We present a model proposing that PTOX associates with the membrane and oxidizes PQH2 only when the oxidation of PQH2 by the cytochrome b6 f complex is limiting forward electron transport due to a high proton gradient across the thylakoid membrane.
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA) Saclay, Institut de Biologie et de Technologie de Saclay, Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, 91191, Gif-sur-Yvette Cedex, France.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Feilke
authors.affiliation: Ecologie, Systématique et Evolution, Université Paris-Sud, Université Paris-Saclay, UMR-CNRS 8079, Bâtiment 362, 91405, Orsay Cedex, France.
authors.forename: Peter
authors.initials: P
authors.lastname: Streb
authors.affiliation: Ecologie, Systématique et Evolution, Université Paris-Sud, Université Paris-Saclay, UMR-CNRS 8079, Bâtiment 362, 91405, Orsay Cedex, France.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Cornic
authors.affiliation: Institut Jean-Pierre Bourgin, INRA, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, F-78026, Versailles, France.|Institut Jean-Pierre Bourgin, AgroParisTech, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, F-78026, Versailles, France.
authors.forename: François
authors.initials: F
authors.lastname: Perreau
authors.affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Kruk
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA) Saclay, Institut de Biologie et de Technologie de Saclay, Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, 91191, Gif-sur-Yvette Cedex, France.
authors.forename: Anja
authors.initials: A
authors.lastname: Krieger-Liszkay
mesh_terms: D002696:Chlamydomonas / Q000201:enzymology* / Q000235:genetics; D004579:Electron Transport / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010788:Photosynthesis / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D018087:Plastids / Q000201:enzymology*; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics*
chemical_list: D010088:Oxidoreductases
keywords: Chlamydomonas reinhardtii PTOX1; Nicotiana tabacum; photooxidative stress; photosynthetic electron transport; plastid terminal oxidase; regulation