title: A Palmitic Acid Elongase Affects Eicosapentaenoic Acid and Plastidial Monogalactosyldiacylglycerol Levels in Nannochloropsis.
abstract: Nannochloropsis species are oleaginous eukaryotes containing a plastid limited by four membranes, deriving from a secondary endosymbiosis. In Nannochloropsis, thylakoid lipids, including monogalactosyldiacylglycerol (MGDG), are enriched in eicosapentaenoic acid (EPA). The need for EPA in MGDG is not understood. Fatty acids are de novo synthesized in the stroma, then converted into very-long-chain polyunsaturated fatty acids (FAs) at the endoplasmic reticulum (ER). The production of MGDG relies therefore on an EPA supply from the ER to the plastid, following an unknown process. We identified seven elongases and five desaturases possibly involved in EPA production in Nannochloropsis gaditana Among the six heterokont-specific saturated FA elongases possibly acting upstream in this pathway, we characterized the highly expressed isoform Δ0-ELO1 Heterologous expression in yeast (Saccharomyces cerevisiae) showed that NgΔ0-ELO1 could elongate palmitic acid. Nannochloropsis Δ0-elo1 mutants exhibited a reduced EPA level and a specific decrease in MGDG In NgΔ0-elo1 lines, the impairment of photosynthesis is consistent with a role of EPA-rich MGDG in nonphotochemical quenching control, possibly providing an appropriate MGDG platform for the xanthophyll cycle. Concomitantly with MGDG decrease, the level of triacylglycerol (TAG) containing medium chain FAs increased. In Nannochloropsis, part of EPA used for MGDG production is therefore biosynthesized by a channeled process initiated at the elongation step of palmitic acid by Δ0-ELO1, thus acting as a committing enzyme for galactolipid production. Based on the MGDG/TAG balance controlled by Δ0-ELO1, this study also provides novel prospects for the engineering of oleaginous microalgae for biotechnological applications.
authors.affiliation: Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.).|Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.); eric.marechal@cea.fr.
authors.forename: Lina-Juana
authors.initials: LJ
authors.lastname: Dolch
authors.affiliation: Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.).|Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.); eric.marechal@cea.fr.
authors.forename: Camille
authors.initials: C
authors.lastname: Rak
authors.affiliation: Padua Algae Research Laboratory, Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy (G.P., T.M.).|Padua Algae Research Laboratory, Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy (G.P., T.M.); eric.marechal@cea.fr.
authors.forename: Giorgio
authors.identifier: 0000-0002-9204-4080
authors.initials: G
authors.lastname: Perin
authors.affiliation: Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.).|Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.); eric.marechal@cea.fr.
authors.forename: Guillaume
authors.identifier: 0000-0002-8140-4968
authors.initials: G
authors.lastname: Tourcier
authors.affiliation: Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.).|Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.); eric.marechal@cea.fr.
authors.forename: Richard
authors.initials: R
authors.lastname: Broughton
authors.affiliation: Fermentalg, 4 Rue Rivière, 33500, Libourne, France (M.L.); and.|Fermentalg, 4 Rue Rivière, 33500, Libourne, France (M.L.); and eric.marechal@cea.fr.
authors.forename: Marina
authors.initials: M
authors.lastname: Leterrier
authors.affiliation: Padua Algae Research Laboratory, Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy (G.P., T.M.).|Padua Algae Research Laboratory, Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy (G.P., T.M.); eric.marechal@cea.fr.
authors.forename: Tomas
authors.identifier: 0000-0002-0803-7591
authors.initials: T
authors.lastname: Morosinotto
authors.affiliation: Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.).|Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.).|Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.) eric.marechal@cea.fr.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Tellier
authors.affiliation: Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.).|Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.) eric.marechal@cea.fr.
authors.forename: Jean-Denis
authors.initials: JD
authors.lastname: Faure
authors.affiliation: Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.).|Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.); eric.marechal@cea.fr.
authors.forename: Denis
authors.initials: D
authors.lastname: Falconet
authors.affiliation: Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.).|Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.); eric.marechal@cea.fr.
authors.forename: Juliette
authors.initials: J
authors.lastname: Jouhet
authors.affiliation: Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.).|Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.); eric.marechal@cea.fr.
authors.forename: Olga
authors.identifier: 0000-0002-8484-2322
authors.initials: O
authors.lastname: Sayanova
authors.affiliation: Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.).|Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.); eric.marechal@cea.fr.
authors.forename: Frédéric
authors.identifier: 0000-0001-9847-3866
authors.initials: F
authors.lastname: Beaudoin
authors.affiliation: Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.).|Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.); eric.marechal@cea.fr.
authors.forename: Eric
authors.identifier: 0000-0002-0060-1696
authors.initials: E
authors.lastname: Maréchal
mesh_terms: D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D020418:Algal Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D015118:Eicosapentaenoic Acid / Q000235:genetics / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005453:Fluorescence; D038983:Galactolipids / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D010788:Photosynthesis; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D018087:Plastids / Q000378:metabolism*; D013107:Sphingolipids / Q000378:metabolism; D058009:Stramenopiles / Q000235:genetics / Q000378:metabolism*; D020524:Thylakoids / Q000235:genetics / Q000648:ultrastructure; D014280:Triglycerides / Q000378:metabolism; D015003:Yeasts / Q000235:genetics
chemical_list: D020418:Algal Proteins; D005231:Fatty Acids, Unsaturated; D038983:Galactolipids; D010940:Plant Proteins; D013107:Sphingolipids; D014280:Triglycerides; C009909:monogalactosyldiacylglycerol; D015118:Eicosapentaenoic Acid; D000123:Acetyltransferases