红花ω3脂肪酸脱氢酶基因的分离及结构分析
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Isolation and structural analysis of safflower ω3 fatty acid desaturase
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    摘要:

    采用RT-PCR和RACE(rapid amplification of cDNA ends)技术,从红花叶片中分离到2个质体类ω3脂肪酸脱氢酶基因(CtFAD7和CtFAD8)的全长cDNA和1个微体类ω3脂肪酸脱氢酶基因(CtFAD3)的部分序列,均已提交至GenBank中。CtFAD7和CtFAD8与其他植物的质体类ω3脂肪酸脱氢酶的相似性分别为61-79 %, 63-78 %。而CtFAD3与其他植物微体类ω3脂肪酸脱氢酶的同源性较高,为60-93 %。氨基酸序列分析表明红花CtFAD3,CtFAD7和CtFAD8均含有3个富含组氨酸的保守结构域,分别为HDCGH,HXXXXXHRTHH 和HVIHH,其中CtFAD7和CtFAD8的 N-端分别含有56 和27 个氨基酸残基的质体信号肽序列。疏水性和跨膜分析表明,红花ω3脂肪酸脱氢酶氨基酸序列均包含4个疏水区域,分别跨膜1-3次。蛋白质二级结构预测结果表明,3个ω3脂肪酸脱氢酶蛋白主要由α螺旋和β折叠组成。通过对CtFAD7和CtFAD8的cDNA和DNA序列比较发现,2个基因的DNA序列中均包含有7个内含子,8个外显子。各内含子在物种间则表现出丰富的多态性,序列和长度大小均各不相同;而从第2# 到7# 外显子的长度和序列相似性在物种间非常保守。比较各内含子的位置可以发现,在内含子出现的位置,均为该基因的保守区。因此,推测ω3脂肪酸脱氢酶基因的内含子对于保证基因在物种进化过程中功能的保守性起着关键作用。

    Abstract:

    One microsomal ω3 fatty acid desaturase gene fragment and two plastidial ω3 fatty acid desaturases cDNA and genomic sequences, designated CtFAD3, CtFAD7 and CtFAD8 have been isolated from safflower (Carthamus tinctorius L.) and submitted to GenBank. Our Blast searches of the deduced amino acid sequences revealed that the similarities of CtFAD7 and CtFAD8 with other plant plastidial ω3 fatty acid desaturases were 61-79 % and 63-78 %, respectively, while CtFAD3 showed higher similarities to other plant microsomal ω3 fatty acid desaturases, 60-93 %. The deduced amino acid sequences of these genes showed three histidine boxes (HDCGH,HXXXXXHRTHH and HVIHH) characteristic of all membrane-bound desaturases, and CtFAD7 and CtFAD8 possess a putative N-termianl signal peptide, 56 and 27 aa respectively. In hydropathy and transmembrane analysis showed that the encoded polypeptides contain four putative hydropathy regions and transmenmbrane one to three times. Protein second-structure indicated that safflower ω3 fatty acid desaturase were composed by α-helix and β-sheet. Compared with the genome structures of safflower CtgFAD7 and CtgFAD8 and other plant plastidial ω3 desaturase genes, all the sequences contained 8 extons and 7 introns. The sequence and size of introns in all plant plastidial ω3 desaturase genes exhibited a wealth polymorphism between species, while the sizes of the internal 6 exons (from 2nd to 7th) were conservative. Comparing the location of the introns revealed that the intron occurs were the conserved regions of the enzyme. We speculated that these introns play an important role in assuring the gene function in the species evolutionary process.

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官玲亮,陈郡雯,刘千,等.红花ω3脂肪酸脱氢酶基因的分离及结构分析[J].植物遗传资源学报,2013,14(5):908-916.

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  • 收稿日期:2012-10-11
  • 最后修改日期:2012-12-27
  • 录用日期:2013-08-09
  • 在线发布日期: 2013-08-21
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