title: A plant porphyria related to defects in plastid import of protochlorophyllide oxidoreductase A.
abstract: The plastid envelope of higher plant chloroplasts is a focal point of plant metabolism. It is involved in numerous pathways, including tetrapyrrole biosynthesis and protein translocation. Chloroplasts need to import a large number of proteins from the cytosol because most are encoded in the nucleus. Here we report that a loss-of-function mutation in the outer plastid envelope 16-kDa protein (oep16) gene causes a conditional seedling lethal phenotype related to defects in import and assembly of NADPH:protochlorophyllide (Pchlide) oxidoreductase A. In the isolated knockout mutant of Arabidopsis thaliana, excess Pchlide accumulated in the dark operated as photosensitizer and provoked cell death during greening. Our results highlight the essential role of the substrate-dependent plastid import pathway of precursor Pchlide oxidoreductase A for seedling survival and the avoidance of developmentally programmed porphyria in higher plants.
authors.affiliation: Université Joseph Fourier et Centre National de la Recherche Scientifique Unité Mixte de Recherche 5575, CERMO, BP53, Grenoble Cedex 9, France.
authors.forename: Stephan
authors.initials: S
authors.lastname: Pollmann
authors.forename: Armin
authors.initials: A
authors.lastname: Springer
authors.forename: Frank
authors.initials: F
authors.lastname: Buhr
authors.forename: Abder
authors.initials: A
authors.lastname: Lahroussi
authors.forename: Iga
authors.initials: I
authors.lastname: Samol
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Bonneville
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Tichtinsky
authors.forename: Diter
authors.initials: D
authors.lastname: von Wettstein
authors.forename: Christiane
authors.initials: C
authors.lastname: Reinbothe
authors.forename: Steffen
authors.initials: S
authors.lastname: Reinbothe
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism*; D030821:Plants, Genetically Modified; D018087:Plastids / Q000378:metabolism*; D011164:Porphyrias / Q000201:enzymology / Q000209:etiology* / Q000235:genetics; D021381:Protein Transport / Q000502:physiology
chemical_list: D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase