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A second functional Î5 fatty acid desaturase in the cellular slime mould Dictyosteliumâdiscoideum
- Saito, Tamao, Morio, Takahiro, Ochiai, Hiroshi
- European journal of biochemistry 2000 v.267 no.6 pp. 1813-1818
- Dictyostelium discoideum, Mortierella alpina, Oryza sativa, amino acid sequences, complementary DNA, databases, fatty acids, gene overexpression, genes, histidine, mutation, nucleotides, stearoyl-CoA desaturase, yeasts
- A cDNA with homology to fatty acid desaturases was selected by searching the cDNA data bank of Dictyosteliumâdiscoideum (http://www.csm.biol.tsukuba.ac.jp/cDNAproject.html) with conserved histidine box motifs. Using this sequence, genomic DNA encoding the Î5 desaturase was amplified from the genomic DNA of D.âdiscoideum, and its desaturase activity was confirmed by the overexpression mutation in D.âdiscoideum and the gainâofâfunction mutation in yeast. The cloned cDNA is 1565 nucleotides in length, and the deduced aminoâacid sequence comprised 467 aminoâacid residues containing an Nâterminal cytochrome b5 domain that shared 43% identity with cytochrome b5 of Oryzaâsativa. The whole sequence was 42% identical to the Î5 desaturase of Mortierellaâalpina. This desaturase is a novel member of the cytochrome b5âcontaining Î5 fatty acid desaturase. As we have already reported one other Î5 desaturase in Dictyostelium, this organism is the first to be confirmed as having two functional Î5 fatty acid desaturase genes. The substrate specificities of the two functional Î5 desaturases of D.âdiscoideum were also examined.