1个油茶Y_2SK_2型脱水素的全长cDNA克隆及生理功能的预测  

A Full-Length cDNA Clone of Typical Y_2SK_2 Dehydrin and Its Speculated Physiological Role in the Seeds of Camellia oleifera

作　　者：胡孝义[1] 谭晓风[1] 张党权[1] 曾艳铃[1] 陈鸿鹏[1] 田晓明[1] 刘巧[1] 

机构地区：[1]中南林业科技大学经济林育种与栽培国家林业局重点实验室,长沙410004

出　　处：《林业科学》2008年第10期55-62,共8页Scientia Silvae Sinicae

基　　金：国家"十一五"科技支撑项目(2006BAD18B0204;2006BAD01A1706);国家自然科学基金项目(30371184);湖南省科学技术厅科技计划项目(06FJ4111)

摘　　要：以构建的油茶EST文库为基础,采用电子克隆技术,分离克隆一个脱水素基因的全长cDNA序列,该基因的cDNA全长1406bp,含一个600bp的CDS,编码200aa的小分子蛋白。推测该基因编码蛋白的分子质量为21ku,等电点7,暂命名为CoDHNI。同源性分析发现该基因的编码蛋白具有2个Y-片段(DEYGNP),1个S-片段(SGSSSSSS),2个K-片段(KIKEKLPG),属于典型的Y2SK2型脱水素。经Blast比对,发现富含苏氨酸的Thr-区在各物种间变异显著,推测该区为油茶所特有,有利于在被保护的大分子表面形成水合层;同时还发现一个十分保守的基序:EDDGQGGRRKK,可能有利于脱水素的磷酸化和亚细胞定位。通过与柑桔和拟南芥的脱水素比较,提出CoDHNI有可能缓冲种子脱水胁迫响应时钙离子的瞬时增高,并可结合重金属离子,以减轻活性氧的危害。Based on a constructed EST library of Camellia oleifera, a full-length cDNA encoding a dehydrin was cloned from its seed by the electronic PCR technique. The cDNA, tentatively designated as CoDHN1, was 1 406 bp long containing an open reading frame of 600 bp. The deduced CoDHN1 protein had 200 amino acid residues, which formed a 21 ku polypeptide with a predicted isoelectric point （pI） of 7. The CoDHN1 protein had two Y-segments, an S-segment and two K-segments. Homology analysis indicated that the Y-segment, S-segment and K-segment of CoDHN1 shared identity with those of other reported dehydrins, indicating that CoDHN belonged to dehydrin superfamily. There was a wide range of variation for Thr-region existed among dehydrins from various species, and the CoDHN1 Thr-region was Camellia oleifera specific, protecting some macromolecules by forming hydrated layer outside of them. A very conserved motif of EDDGQGGRRKK was found in CoDHN1, and it might contribute to dehydrin＇ s phosphorylation and subcellular localization. By comparison with dehydrins from citrus and Arabidopsis respectively, it was proposed that CoDHN1 might serve as a buffer for transiently increased Ca^2＋ when the matured seeds was under the condition of desiccation stress to some extent, and that CoDHN1 might bind heavy metal ions such as Cu^2＋ , Ni^2＋ , Zn^2＋ , Co^2 ＋ , Fe^3＋ and hence scavenge reactive oxygen species to alleviate toxin caused by them.

关 键 词：油茶 脱水素基因 CDNA文库 RACE 生理功能 生物信息学 

分 类 号：S718.46[农业科学—林学] Q943.2[生物学—植物学]