Channeling of eukaryotic diacylglycerol into the biosynthesis of plastidial phosphatidylglycerol.
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.
Fritz
Markus
M
Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany; Max-Planck-Gesellschaft, Generalverwaltung, Hofgartenstrasse 8, D-80539 München, Germany.
Lokstein
Heiko
H
Institut für Biochemie und Biologie, Universität Potsdam, Pflanzenphysiologie, Karl-Liebknecht-Strasse 24-25, D-14476 Golm, Germany.
Hackenberg
Dieter
D
Institut für Biologie/Pflanzenphysiologie, Humboldt-Universität zu Berlin, Unter den Linden 6, D-10099 Berlin.
Welti
Ruth
R
Division of Biology, Kansas State University, Kansas Lipidomics Research Center, Manhattan, Kansas 66506-4901.
Roth
Mary
M
Division of Biology, Kansas State University, Kansas Lipidomics Research Center, Manhattan, Kansas 66506-4901.
Zähringer
Ulrich
U
Leibniz-Zentrum für Medizin und Biowissenschaften, Forschungszentrum Borstel, Parkallee 4, D-23845 Borstel, Germany.
Fulda
Martin
M
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.
Hellmeyer
Wiebke
W
Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany.
Ott
Claudia
C
Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany.
Wolter
Frank P
FP
Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany; Bundesverband Deutscher Pflanzenzüchter, GVSmbH, Kaufmannstrasse 71-73, D-53115 Bonn, Germany.
Heinz
Ernst
E
Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany.
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
D004075:Diglycerides; D029968:Escherichia coli Proteins; D010715:Phosphatidylglycerols; D019852:Diacylglycerol Kinase