title: Putative role of the malate valve enzyme NADP-malate dehydrogenase in H2O2 signalling in Arabidopsis.
abstract: In photosynthetic organisms, sudden changes in light intensity perturb the photosynthetic electron flow and lead to an increased production of reactive oxygen species. At the same time, thioredoxins can sense the redox state of the chloroplast. According to our hypothesis, thioredoxins and related thiol reactive molecules downregulate the activity of H2O2-detoxifying enzymes, and thereby allow a transient oxidative burst that triggers the expression of H2O2 responsive genes. It has been shown recently that upon light stress, catalase activity was reversibly inhibited in Chlamydomonas reinhardtii in correlation with a transient increase in the level of H2O2. Here, it is shown that Arabidopsis thaliana mutants lacking the NADP-malate dehydrogenase have lost the reversible inactivation of catalase activity and the increase in H2O2 levels when exposed to high light. The mutants were slightly affected in growth and accumulated higher levels of NADPH in the chloroplast than the wild-type. We propose that the malate valve plays an essential role in the regulation of catalase activity and the accumulation of a H2O2 signal by transmitting the redox state of the chloroplast to other cell compartments.
authors.affiliation: Commissariat à l'Energie Atomique (CEA) Saclay, iBiTec-S, CNRS UMR 8221, Service de Bioénergétique, Biologie Structurale et Mécanisme, , 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Eiri
authors.initials: E
authors.lastname: Heyno
authors.forename: Gilles
authors.initials: G
authors.lastname: Innocenti
authors.forename: Stéphane D
authors.initials: SD
authors.lastname: Lemaire
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Issakidis-Bourguet
authors.forename: Anja
authors.initials: A
authors.lastname: Krieger-Liszkay
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D002374:Catalase / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism / Q000502:physiology*; D017931:DNA Primers / Q000235:genetics; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D005453:Fluorescence; D006861:Hydrogen Peroxide / Q000378:metabolism*; D015151:Immunoblotting; D050538:Malate Dehydrogenase (NADP+) / Q000172:deficiency / Q000378:metabolism*; D008954:Models, Biological; D010788:Photosynthesis / Q000502:physiology*; D010936:Plant Extracts / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D013879:Thioredoxins; D006861:Hydrogen Peroxide; D050538:Malate Dehydrogenase (NADP+); D002374:Catalase
keywords: catalase; light stress; malate valve; reactive oxygen species