First published online March 13, 2003; 10.1104/pp.102.018317
Plant Physiol, April 2003, Vol. 131, pp. 1648-1660
New Insight into Phaeodactylum tricornutum Fatty Acid
Metabolism. Cloning and Functional Characterization of Plastidial and
Microsomal 12-Fatty Acid Desaturases1,[w]
Frédéric
Domergue,*
Patricia
Spiekermann,
Jens
Lerchl,2
Christoph
Beckmann,
Oliver
Kilian,
Peter G.
Kroth,
Wilhem
Boland,
Ulrich
Zähringer, and
Ernst
Heinz
Institut für Allgemeine Botanik, Universität Hamburg,
Ohnhorststrasse 18, 22609 Hamburg, Germany (F.D., P.S., E.H.); BASF
Plant Science GmbH, BPS-A30, D-67056 Ludwigshafen, Germany (J.L.);
Fachbereich Biologie, Universität Konstanz, D-78457 Konstanz,
Germany (O.K., P.K.); Max-Planck-Institut für Chemische
Ökologie, Carl-Zeiss-Promenade 10, D-07745 Jena, Germany (C.B.,
W.B.); and Forschungszentrum Borstel, Parkallee 22, D-23845 Borstel,
Germany (U.Z.)
In contrast to 16:3 plants like rapeseed (Brassica
napus), which contain -linolenic acid
(18:3 9,12,15) and hexadecatrienoic acid
(16:3 7,10,13) as major polyunsaturated fatty
acids in leaves, the silica-less diatom Phaeodactylum
tricornutum contains eicosapentaenoic acid (EPA;
20:5 5,8,11,14,17) and a different isomer of
hexadecatrienoic acid (16:3 6,9,12). In this
report, we describe the characterization of two cDNAs having sequence
homology to 12-fatty acid desaturases from higher plants. These
cDNAs were shown to code for a microsomal and a plastidial
12-desaturase (PtFAD2 and PtFAD6, respectively) by heterologous
expression in yeast (Saccharomyces cerevisiae) and Synechococcus, respectively. Using these systems in the
presence of exogenously supplied fatty acids, the substrate
specificities of the two desaturases were determined and compared with
those of the corresponding rapeseed enzymes (BnFAD2 and BnFAD6). The microsomal desaturases were similarly specific for oleic acid (18:1 9), suggesting that PtFAD2 is involved
in the biosynthesis of EPA. In contrast, the plastidial desaturase from
the higher plant and the diatom clearly differed. Although the rapeseed
plastidial desaturase showed high activity toward the 9-fatty acids
18:1 9 and 16:1 7,
in line with the fatty acid composition of rapeseed leaves, the enzyme
of P. tricornutum was highly specific for
16:1 9. Our results indicate that in contrast
to EPA, which is synthesized in the microsomes, the hexadecatrienoic
acid isomer found in P. tricornutum
(16:3 6,9,12) is of plastidial origin.
1
This work was supported in part by the European
Community program Human Potential (Marie Curie Fellowship under
contract no. HPMF-CT-1999-00148 to F.D.), by the Fachagentur
für Nachwachsende Rohstoffe (grant to P.S.), by the Deutsche
Forschungsgemeinschaft (grant no. Transregio-SFB TR1, TP A1 to P.G.K.
and grant no. SFB 436 to W.B.), by the Fonds der Chemischen Industrie,
and by BASF Plant Science GmbH.
2
Present address: Plant Science Sweden AB,
SE-26831 Svalöv, Sweden.
[w]
The online version of this article contains Web-only
data. The supplemental material is available at www.plantphysiol.org.
*
Corresponding author; e-mail
fredDo{at}botanik.uni-hamburg.de; fax 49-40-42816-254.
© 2003 American Society of Plant Biologists
This article has been cited by other articles:

|
 |

|
 |
 
M. Hoffmann, E. Hornung, S. Busch, N. Kassner, P. Ternes, G. H. Braus, and I. Feussner
A Small Membrane-peripheral Region Close to the Active Center Determines Regioselectivity of Membrane-bound Fatty Acid Desaturases from Aspergillus nidulans
J. Biol. Chem.,
September 14, 2007;
282(37):
26666 - 26674.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
N. Sato and T. Moriyama
Genomic and Biochemical Analysis of Lipid Biosynthesis in the Unicellular Rhodophyte Cyanidioschyzon merolae: Lack of a Plastidic Desaturation Pathway Results in the Coupled Pathway of Galactolipid Synthesis
Eukaryot. Cell,
June 1, 2007;
6(6):
1006 - 1017.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
R. M. Morgan-Kiss, J. C. Priscu, T. Pocock, L. Gudynaite-Savitch, and N. P. A. Huner
Adaptation and Acclimation of Photosynthetic Microorganisms to Permanently Cold Environments
Microbiol. Mol. Biol. Rev.,
March 1, 2006;
70(1):
222 - 252.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
A. Montsant, K. Jabbari, U. Maheswari, and C. Bowler
Comparative Genomics of the Pennate Diatom Phaeodactylum tricornutum
Plant Physiology,
February 1, 2005;
137(2):
500 - 513.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
F. Domergue, A. Abbadi, C. Ott, T. K. Zank, U. Zahringer, and E. Heinz
Acyl Carriers Used as Substrates by the Desaturases and Elongases Involved in Very Long-chain Polyunsaturated Fatty Acids Biosynthesis Reconstituted in Yeast
J. Biol. Chem.,
September 12, 2003;
278(37):
35115 - 35126.
[Abstract]
[Full Text]
[PDF]
|
 |
|
|
|