播娘蒿叶绿体型△12脱饱和酶的功能研究

Further functional characterization of a chloroplast△12 fatty acid desaturases from Descurainia sophia

本文应用RT-PCR和RACE方法扩增出了的播娘蒿叶绿体型△12脱饱和酶(Ds-FAD2CHL)全长cDNA,其完整编码框为1344 bp,编码447个氨基酸;该基因ORF在酵母Saccharamyces cerevisiae中的表达阐明其功能为将18:1^(△9)脱饱和生成亚油酸(18:2^(△9,12));进一步切除叶绿体信号肽后的脱饱和酶在酵母中把18:1^(△9)脱饱和生成18:2^(△9,12)的效率提高了3.72%;通过GC/MS分析转基因酵母的磷脂及酰基辅酶A库发现,该脱饱和酶的作用底物为磷脂,而不是以酰基辅酶A形式结合的脂肪酸.

A chloroplast△12 fatty acid desaturases gene from Descurainia Sophia （DsFAD2CHL） was isolated by RT-PCR and RACE. It has an open reading frame of 1344 bp, which encodes 447 amino acids. Expression of this cDNA in Saccharamyces cerevisiae revealed that the desaturase had a function that introduce an double bond into 18：1△9 to produce linoleic acid （18.2△9,l2）, and the enzyme removing a plastidial signal peptide had a 3.72% higher desaturation conversion rate. Further phospholipids and acyl-CoAs pool analysis by GC/MS showed that the substrate of this enzyme was combined with phos- pholipids but not acyl-CoA.