title: Channeling of eukaryotic diacylglycerol into the biosynthesis of plastidial phosphatidylglycerol.
abstract: Plastidial glycolipids contain diacylglycerol (DAG) moieties, which are either synthesized in the plastids (prokaryotic lipids) or originate in the extraplastidial compartment (eukaryotic lipids) necessitating their transfer into plastids. In contrast, the only phospholipid in plastids, phosphatidylglycerol (PG), contains exclusively prokaryotic DAG backbones. PG contributes in several ways to the functions of chloroplasts, but it is not known to what extent its prokaryotic nature is required to fulfill these tasks. As a first step toward answering this question, we produced transgenic tobacco plants that contain eukaryotic PG in thylakoids. This was achieved by targeting a bacterial DAG kinase into chloroplasts in which the heterologous enzyme was also incorporated into the envelope fraction. From lipid analysis we conclude that the DAG kinase phosphorylated eukaryotic DAG forming phosphatidic acid, which was converted into PG. This resulted in PG with 2-3 times more eukaryotic than prokaryotic DAG backbones. In the newly formed PG the unique Delta3-trans-double bond, normally confined to 3-trans-hexadecenoic acid, was also found in sn-2-bound cis-unsaturated C18 fatty acids. In addition, a lipidomics technique allowed the characterization of phosphatidic acid, which is assumed to be derived from eukaryotic DAG precursors in the chloroplasts of the transgenic plants. The differences in lipid composition had only minor effects on measured functions of the photosynthetic apparatus, whereas the most obvious phenotype was a significant reduction in growth.
authors.affiliation: Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany; Max-Planck-Gesellschaft, Generalverwaltung, Hofgartenstrasse 8, D-80539 München, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Fritz
authors.affiliation: Institut für Biochemie und Biologie, Universität Potsdam, Pflanzenphysiologie, Karl-Liebknecht-Strasse 24-25, D-14476 Golm, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Lokstein
authors.affiliation: Institut für Biologie/Pflanzenphysiologie, Humboldt-Universität zu Berlin, Unter den Linden 6, D-10099 Berlin.
authors.forename: Dieter
authors.initials: D
authors.lastname: Hackenberg
authors.affiliation: Division of Biology, Kansas State University, Kansas Lipidomics Research Center, Manhattan, Kansas 66506-4901.
authors.forename: Ruth
authors.initials: R
authors.lastname: Welti
authors.affiliation: Division of Biology, Kansas State University, Kansas Lipidomics Research Center, Manhattan, Kansas 66506-4901.
authors.forename: Mary
authors.initials: M
authors.lastname: Roth
authors.affiliation: Leibniz-Zentrum für Medizin und Biowissenschaften, Forschungszentrum Borstel, Parkallee 4, D-23845 Borstel, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Zähringer
authors.affiliation: Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany; Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Georg-August Universität Göttingen, Biochemie der Pflanze, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany, and the. Electronic address: mfulda@gwdg.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Fulda
authors.affiliation: Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany.
authors.forename: Wiebke
authors.initials: W
authors.lastname: Hellmeyer
authors.affiliation: Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Ott
authors.affiliation: Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany; Bundesverband Deutscher Pflanzenzüchter, GVSmbH, Kaufmannstrasse 71-73, D-53115 Bonn, Germany.
authors.forename: Frank P
authors.initials: FP
authors.lastname: Wolter
authors.affiliation: Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany.
authors.forename: Ernst
authors.initials: E
authors.lastname: Heinz
mesh_terms: D019852:Diacylglycerol Kinase / Q000096:biosynthesis* / Q000235:genetics; D004075:Diglycerides / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D010715:Phosphatidylglycerols / Q000096:biosynthesis*; D010788:Photosynthesis / Q000502:physiology; D030821:Plants, Genetically Modified; D020524:Thylakoids / Q000201:enzymology* / Q000235:genetics; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics
chemical_list: D004075:Diglycerides; D029968:Escherichia coli Proteins; D010715:Phosphatidylglycerols; D019852:Diacylglycerol Kinase