title: The plastid outer envelope protein OEP16 affects metabolic fluxes during ABA-controlled seed development and germination.
abstract: Previously, the OEP16.1 channel pore in the outer envelope membrane of mature pea (Pisum sativum) chloroplasts in vitro has been characterized to be selective for amino acids. Isolation of OEP16.2, a second OEP16 isoform from pea, in the current study allowed membrane localization and gene expression of OEP16 to be followed throughout seed development and germination of Arabidopsis thaliana and P. sativum. Thereby it can be shown on the transcript and protein level that the isoforms OEP16.1 and OEP16.2 in both plant species are alternating: whereas OEP16.1 is prominent in early embryo development and first leaves of the growing plantlet, OEP16.2 dominates in late seed development stages, which are associated with dormancy and desiccation, as well as early germination events. Further, OEP16.2 expression in seeds is under control of the phytohormone abscisic acid (ABA), leading to an ABA-hypersensitive phenotype of germinating oep16 knockout mutants. In consequence, the loss of OEP16 causes metabolic imbalance, in particular that of amino acids during seed development and early germination. It is thus concluded that in vivo OEP16 most probably functions in shuttling amino acids across the outer envelope of seed plastids.
authors.affiliation: Department Biologie I, Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Pudelski
authors.forename: Annette
authors.initials: A
authors.lastname: Schock
authors.forename: Stefan
authors.initials: S
authors.lastname: Hoth
authors.forename: Ruslana
authors.initials: R
authors.lastname: Radchuk
authors.forename: Hans
authors.initials: H
authors.lastname: Weber
authors.forename: Jörg
authors.initials: J
authors.lastname: Hofmann
authors.forename: Uwe
authors.initials: U
authors.lastname: Sonnewald
authors.forename: Jürgen
authors.initials: J
authors.lastname: Soll
authors.forename: Katrin
authors.initials: K
authors.lastname: Philippar
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D001692:Biological Transport; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D055786:Gene Knockout Techniques; D018525:Germination / Q000502:physiology*; D009154:Mutation; D018532:Pisum sativum / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D018087:Plastids / Q000378:metabolism; D020033:Protein Isoforms; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
chemical_list: D060365:Chloroplast Proteins; D010937:Plant Growth Regulators; D020033:Protein Isoforms; D000040:Abscisic Acid