title: Isolation of a novel C18-Δ9 polyunsaturated fatty acid specific elongase gene from DHA-producing Isochrysis galbana H29 and its use for the reconstitution of the alternative Δ8 pathway in Saccharomyces cerevisiae.
abstract: A novel gene (IgASE2) encoding a C18-Δ9 polyunsaturated fatty acids specific (C18-Δ9-PUFAs-specific) elongase was isolated and characterized from DHA-rich microalga, Isochrysis galbana H29. The IgASE2 gene was 1,653 bp in length, contained a 786 bp ORF encoding a protein of 261 amino acids that shared 87% identity with Δ9 elongase, IgASE1, and possessed a 44 bp 5'-untranslated region (5'-UTR) and a 823 bp 3'-untranslated region (3'-UTR). IgASE2, by its heterologous expression in Saccharomyces cerevisiae, elongated linoleic acid (LA, 18:2n-6) and α-linolenic (ALA, 18:3n-3) to eicosadienoic acid (EDA, 20:2n-6) and eicosatrienoic acid (ETrA, 20:3n-3), respectively. The conversions of LA to EDA and ALA to ETrA were 57.6 and 56.1%, respectively. Co-expression of this elongase with Δ8 desaturase required for the synthesis of C20-polyunsaturated fatty acids resulted in the accumulation of dihomo-γ-linolenic acid (20:3n-6) from LA and eicosatetraenoic acid (20:4n-6) from ALA. These results demonstrated that IgASE2 exhibited C18-Δ9-PUFAs-specific elongase activity and the alternative Δ8 pathway was reconstituted.
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, Nankai University, Tianjin 300071, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Xiuyuan
authors.initials: X
authors.lastname: Ou
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Yang
authors.forename: Dongquan
authors.initials: D
authors.lastname: Guo
authors.forename: Xueyan
authors.initials: X
authors.lastname: Qian
authors.forename: Laijun
authors.initials: L
authors.lastname: Xing
authors.forename: Mingchun
authors.initials: M
authors.lastname: Li
mesh_terms: D000123:Acetyltransferases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D001711:Biotransformation; D000081031:Fatty Acid Elongases; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D058087:Haptophyta / Q000201:enzymology* / Q000235:genetics*; D019787:Linoleic Acid / Q000378:metabolism; D060847:Metabolic Engineering; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011994:Recombinant Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D017962:alpha-Linolenic Acid / Q000378:metabolism
chemical_list: D005231:Fatty Acids, Unsaturated; D011994:Recombinant Proteins; D017962:alpha-Linolenic Acid; D019787:Linoleic Acid; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases