title: delta 9 Acyl-lipid desaturases of cyanobacteria. Molecular cloning and substrate specificities in terms of fatty acids, sn-positions, and polar head groups.
abstract: In cyanobacteria, the biosynthesis of unsaturated fatty acids is initiated by delta 9 acyl-lipid desaturase which introduces the first double bond at the delta 9 position of a saturated fatty acid that has been esterified to a glycerolipid. We have cloned genes, designated desC, for delta 9 acyl-lipid desaturases from two cyanobacteria, namely Anabaena variabilis and Synechocystis sp. PCC 6803. These desaturases, when expressed in Escherichia coli, desaturated stearic acid to yield oleic acid at the C-1 positions of phosphatidylethanolamine and phosphatidylglycerol, but did not desaturate palmitic acid, palmitoleic acid, and cis-vaccenic acid. These results indicate that the delta 9 acyl-lipid desaturases are specific to stearic acid esterified at the C-1 position of a glycerolipid and are nonspecific with respect to the polar head group of the glycerolipid. The deduced amino acid sequences of the delta 9 acyl-lipid desaturases are similar in part to those of stearoyl-CoA desaturases of the rat, the mouse, and Saccharomyces cerevisiae, but not to those of acyl-(acyl-carrier-protein) desaturases of higher plants.
authors.affiliation: National Institute for Basic Biology, Okazaki, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sakamoto
authors.forename: H
authors.initials: H
authors.lastname: Wada
authors.forename: I
authors.initials: I
authors.lastname: Nishida
authors.forename: M
authors.initials: M
authors.lastname: Ohmori
authors.forename: N
authors.initials: N
authors.lastname: Murata
mesh_terms: D000595:Amino Acid Sequence; D017033:Anabaena / Q000201:enzymology / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000201:enzymology / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D044943:Fatty Acid Desaturases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D005798:Genes, Bacterial / Q000235:genetics*; D008055:Lipids / Q000737:chemistry; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D013230:Stearoyl-CoA Desaturase; D013379:Substrate Specificity
chemical_list: D005227:Fatty Acids; D008055:Lipids; D011994:Recombinant Proteins; D044943:Fatty Acid Desaturases; D013230:Stearoyl-CoA Desaturase; C029627:delta-9 fatty acid desaturase