油茶脱水素样蛋白的基因克隆与序列分析及其生理功能预测  

cDNA Cloning,Sequence Analysis and Physiological Role Speculation of A Dehydrin-like Protein from Camellia oleifera

作　　者：胡孝义[1] 谭晓风[1] 田晓明[1] 刘巧[1] 罗茜[1] 谢鹏[1] 曾艳玲[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：《西北植物学报》2008年第8期1541-1548,共8页Acta Botanica Boreali-Occidentalia Sinica

基　　金：中南林业科技大学与湖南省教育厅研究生创新基金(2006bx01);国家"十一五"科技支撑项目(2006BAD18B0204;2006BAD01A1706)

摘　　要：以油茶EST文库为基础,采用5-′RACE技术,分离克隆了一个脱水素样基因的全长cDNA序列(GenBank接受号EU856537),同源分析表明其编码的208 aa的小分子蛋白(id号ACF72673)属于SK2型脱水素,命名为CoDHN2.CoDHN2的肽链内2个类K-片段间富含苏氨酸,有别于脱水素一般性结构特点,并且同油茶种子中另一类脱水素一样也具有一个十分保守的基序(EDDGQAGRRKK),这可能有利于脱水素的磷酸化和亚细胞定位;采用多种方法预测其二级结构,表明CoDHN2为内在性无规则蛋白,但其中远离C端的一个类K-片段可形成两亲性α-螺旋.CoDHN2含有较多的组氨酸残基以及良好的可溶性,推测它可结合金属离子从而减少活性氧的来源并清除活性氧,并在生理脱水时充当缓冲液.结合其它物种脱水素的研究进展,认为CoDHN2极有可能在油茶油脂合成高峰期同正在发育的脂体结合而保护脂体免受活性氧危害,这为油茶种子细胞的脂体发育研究提出了一个新的方向.Based on a constructed cDNA library of Camellia oleifera, a full-length cDNA （GenBank accession number： EU856537） encoding a dehydrin like protein （id. ACF72673） composed of 208 amino acids, was cloned from the seeds by 5′ RACE technique. This putative protein should belong to the SK2-type dehydrin by homology analysis,designated as CoDHN2. In its polypeptide the region between the domains of the two similar K-segments is rich in threonine,which is different from the general characteristics of other dehydrins. CoDHN2 dehydrin shared a highly conserved motif of EDDGQGGRRKK,which might contribute to dehydrin＇s phosphorylation and hence subcellular localization,as another dehydrin do in the seeds of C. oleifera. Prediction of secondary structure via various methods showed that CoDHN2 was intrinsically unstructured,but one of its K-segments can be changed into α- amphipathic helix. Due to its relatively rich histidine content and good solvent accessibility,It was proposed that CoDHN2 may bind heavy metal ions, and thus eliminate ROS sources caused by these ions and scavenge ROS,or may also serve as buffer for some physiological process under the condition of water deficient. Considering the progress of study on dehydrin,it was speculated that the CoDHN2 was very possible to bind the developing lipid body and protect them against the ROS during rapid biosynthesis of lipid in the C. oleifera seeds,which give a new clue to study the development of lipid body in the seeds of C. oleifera.

关 键 词：油茶 脱水素基因 CDNA文库 RACE 生理功能 

分 类 号：Q789[生物学—分子生物学]