Expression of the Isochrysis C18-delta9 polyunsaturated fatty acid specific elongase component alters Arabidopsis glycerolipid profiles.
A cDNA isolated from the prymnesiophyte micro-alga Isochrysis galbana, designated IgASE1, encodes a fatty acid elongating component that is specific for linoleic acid (C18:2n-6) and alpha-linolenic acid (C18:3n-3). Constitutive expression of IgASE1 in Arabidopsis resulted in the accumulation of eicosadienoic acid (EDA; C20:2n-6) and eicosatrienoic acid (ETrA; C20:3n-3) in all tissues examined, with no visible effects on plant morphology. Positional analysis of the various lipid classes indicated that these novel fatty acids were largely excluded from the sn-2 position of chloroplast galactolipids and seed triacylglycerol, whereas they were enriched in the same position in phosphatidylcholine. EDA and ETrA are precursors of arachidonic acid (C20:4n-6), eicosapentaenoic acid (C20:5n-3), and docosahexaenoic acid (C22:6n-3) synthesized via the so-called omega6 Delta8 desaturase and omega3 Delta8 desaturase biosynthetic pathways, respectively. The synthesis of significant quantities of EDA and ETrA in a higher plant is therefore a key step in the production of very long chain polyunsaturated fatty acid in oil-seed species. The results are further discussed in terms of prokaryotic and eukaryotic pathways of lipid synthesis in plants.
Fraser
Thomas Colin Michael
TC
School of Biological Sciences, University of Bristol, Bristol BS8 1UG, United Kingdom. t.c.m.fraser@bristol.ac.uk
Qi
Baoxiu
B
Elhussein
Salah
S
Chatrattanakunchai
Sunantha
S
Stobart
Allan Keith
AK
Lazarus
Colin Michael
CM
D000123:Acetyltransferases / Q000235:genetics* / Q000378:metabolism; D020418:Algal Proteins / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D056890:Eukaryota / Q000737:chemistry / Q000201:enzymology / Q000235:genetics*; D044943:Fatty Acid Desaturases / Q000378:metabolism; D000081031:Fatty Acid Elongases; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis* / Q000737:chemistry; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D006017:Glycolipids / Q000096:biosynthesis* / Q000737:chemistry; D019787:Linoleic Acid / Q000096:biosynthesis / Q000737:chemistry; D008563:Membrane Lipids / Q000502:physiology; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D030821:Plants, Genetically Modified; D012639:Seeds / Q000737:chemistry / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017962:alpha-Linolenic Acid / Q000096:biosynthesis / Q000737:chemistry
D020418:Algal Proteins; D018076:DNA, Complementary; D005231:Fatty Acids, Unsaturated; D006017:Glycolipids; D008563:Membrane Lipids; D017962:alpha-Linolenic Acid; D019787:Linoleic Acid; D044943:Fatty Acid Desaturases; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases