播娘蒿甜菜碱醛脱氢酶基因的克隆和表达分析

采用RT-PCR技术克隆了播娘蒿的甜菜碱醛脱氢酶基因全长cDNA序列(DsBADH)。DsBADHcD-NA序列全长1653bp,其中开放阅读框长1503bp,编码一个由501个氨基酸残基组成的蛋白质,推测的蛋白质相对分子质量为54kD,pI为5.5。序列比对结果表明DsBADH与其它物种的BADHs无论在核酸水平还是在蛋白质水平上都表现较高的同源性,表明BADH基因家族具有较高的保守性。DsBADH基因的氨基酸序列在进化上与同属十字花科植物BADH基因距离较近。蛋白质序列存在一个编码十肽的高度保守序列,该结构在醛脱氢酶中是高度保守的,这些残基可能包含NAD 结合位点及酶催化位点,而且含有与酶功能有关的醛脱氢酶高度保守的氨基酸残基Cys,表明DsBADH可编码活性蛋白。N端存在信号肽,初步将该酶定位于叶绿体。半定量RT-PCR分析表明,DsBADH在根、茎、叶以及角果中均表达,但在角果中的表达显著高于其它组织,而且表明DsBADH受盐诱导正调节表达。

Molecular Cloning and Characterization of a Betaine-aldehyde Dehydrogenase Gene in Descurainia Sophia

A novel cDNA encoding betaine aldehyde dehydrogenase (BADH) was cloned from Descurainia sophia by RT-PCR and designated as DsBADH. The full-length cDNA was 1 653 bp in length with a complete open reading frame of 1 506bp, encoding 501 amino acid with a predicted molecular mass of 54kD and a pI of 5.5. The deduced products contained the conserved domain sequence of the aldehyde dehydrogenase and cysteine associated with aldehyde dehydrogenase function. N-terminal signal peptide revealed that DsBADH was targeted into chloroplast. Sequence alignment showed that DsBADH presented higher similarity with other BADHs at the level of both nucleic acid and amino acid. Phylogenetic tree analysis showed that DsBADH fell into a small group with Cruciferous species. Semi-quantitative RT-PCR results revealed that DsBADH was expressed in roots, stems, leaves and siliques, but the expressing level was the highest in siliques. In addition, the expression of DsBADH gene was induced by salt stress in all tissues detected.