Format

Send to

Choose Destination
Plant Physiol. 2017 Jan;173(1):742-759. doi: 10.1104/pp.16.01420. Epub 2016 Nov 28.

A Palmitic Acid Elongase Affects Eicosapentaenoic Acid and Plastidial Monogalactosyldiacylglycerol Levels in Nannochloropsis.

Author information

1
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.).
2
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.
3
Padua Algae Research Laboratory, Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy (G.P., T.M.).
4
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.
5
Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.).
6
Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.); eric.marechal@cea.fr.
7
Fermentalg, 4 Rue Rivière, 33500, Libourne, France (M.L.); and.
8
Fermentalg, 4 Rue Rivière, 33500, Libourne, France (M.L.); and eric.marechal@cea.fr.
9
Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.).
10
Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.) eric.marechal@cea.fr.

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.

PMID:
27895203
PMCID:
PMC5210741
DOI:
10.1104/pp.16.01420
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center