title: Isolation and characterization of genes from the marine microalga Pavlova salina encoding three front-end desaturases involved in docosahexaenoic acid biosynthesis.
abstract: The marine microalga Pavlova salina produces lipids containing approximately 50% omega-3 long chain polyunsaturated fatty acids (LC-PUFA) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Three cDNA sequences, designated PsD4Des, PsD5Des, PsD8Des, were isolated from P. salina and shown to encode three front-end desaturases with Delta4, Delta5 and Delta8 specificity, respectively. Southern analysis indicated that the P. salina genome contained single copies of all three front-end fatty acid desaturase genes. When grown at three different temperatures, analysis of fatty acid profiles indicated P. salina desaturation conversions occurred with greater than 95% efficiency. Real-Time PCR revealed that expression of PsD8Des was higher than for the other two genes under normal growth conditions, while PsD5Des had the lowest expression level. The deduced amino acid sequences from all three genes contained three conserved histidine boxes and a cytochrome b(5) domain. Sequence alignment showed that the three genes were homologous to corresponding desaturases from other microalgae and fungi. The predicted activities of these three front-end desaturases leading to the synthesis of LC-PUFA were also confirmed in yeast and in higher plants.
authors.affiliation: Food Futures National Research Flagship, CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia. Xue-Rong.Zhou@csiro.au
authors.forename: Xue-Rong
authors.initials: XR
authors.lastname: Zhou
authors.forename: Stanley S
authors.initials: SS
authors.lastname: Robert
authors.forename: James R
authors.initials: JR
authors.lastname: Petrie
authors.forename: Dion M F
authors.initials: DM
authors.lastname: Frampton
authors.forename: Maged P
authors.initials: MP
authors.lastname: Mansour
authors.forename: Susan I
authors.initials: SI
authors.lastname: Blackburn
authors.forename: Peter D
authors.initials: PD
authors.lastname: Nichols
authors.forename: Allan G
authors.initials: AG
authors.lastname: Green
authors.forename: Surinder P
authors.initials: SP
authors.lastname: Singh
mesh_terms: D020418:Algal Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015139:Blotting, Southern; D002849:Chromatography, Gas; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004281:Docosahexaenoic Acids / Q000378:metabolism*; D056890:Eukaryota / Q000201:enzymology / Q000235:genetics*; D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D020418:Algal Proteins; D018076:DNA, Complementary; D005231:Fatty Acids, Unsaturated; D007527:Isoenzymes; D004281:Docosahexaenoic Acids; D044943:Fatty Acid Desaturases