title: Isolation and functional characterisation of the genes encoding Δ(8)-sphingolipid desaturase from Brassica rapa.
abstract: Δ(8)-Sphingolipid desaturase is the key enzyme that catalyses desaturation at the C8 position of the long-chain base of sphingolipids in higher plants. There have been no previous studies on the genes encoding Δ(8)-sphingolipid desaturases in Brassica rapa. In this study, four genes encoding Δ(8)-sphingolipid desaturases from B. rapa were isolated and characterised. Phylogenetic analyses indicated that these genes could be divided into two groups: BrD8A, BrD8C and BrD8D in group I, and BrD8B in group II. The two groups of genes diverged before the separation of Arabidopsis and Brassica. Though the four genes shared a high sequence similarity, and their coding desaturases all located in endoplasmic reticulum, they exhibited distinct expression patterns. Heterologous expression in Saccharomyces cerevisiae revealed that BrD8A/B/C/D were functionally diverse Δ(8)-sphingolipid desaturases that catalyse different ratios of the two products 8(Z)- and 8(E)-C18-phytosphingenine. The aluminium tolerance of transgenic yeasts expressing BrD8A/B/C/D was enhanced compared with that of control cells. Expression of BrD8A in Arabidopsis changed the ratio of 8(Z):8(E)-C18-phytosphingenine in transgenic plants. The information reported here provides new insights into the biochemical functional diversity and evolutionary relationship of Δ(8)-sphingolipid desaturase in plants and lays a foundation for further investigation of the mechanism of 8(Z)- and 8(E)-C18-phytosphingenine biosynthesis.
authors.affiliation: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Shu-Fen
authors.initials: SF
authors.lastname: Li
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Song
authors.forename: Wei-Bo
authors.initials: WB
authors.lastname: Yin
authors.forename: Yu-Hong
authors.initials: YH
authors.lastname: Chen
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Ji-Lin
authors.initials: JL
authors.lastname: Li
authors.forename: Richard R-C
authors.initials: RR
authors.lastname: Wang
authors.forename: Zan-Min
authors.initials: ZM
authors.lastname: Hu
mesh_terms: D000535:Aluminum / Q000633:toxicity; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D055162:Biocatalysis; D029741:Brassica rapa / Q000201:enzymology* / Q000235:genetics*; D019143:Evolution, Molecular; D018628:Gene Dosage; D018506:Gene Expression Regulation, Plant; D042541:Intracellular Space / Q000201:enzymology; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013110:Sphingosine / Q000031:analogs & derivatives / Q000096:biosynthesis; D014026:Nicotiana / Q000166:cytology / Q000235:genetics
chemical_list: D000535:Aluminum; D010088:Oxidoreductases; C115532:sphingolipid desaturase; C012491:phytosphingosine; D013110:Sphingosine