橡胶树AtCAB1同源基因的克隆及其在稳定与衰老期叶片中的差异分析

Molecular Cloning of a cDNA Homologue to Arabidopsis CAB1 from Hevea brasiliensis and Its Different Expression in Mature and Senescent Rubber Tree Leaves

以一编码蛋白与拟南芥的CAB1高度相似的EST序列作为探针,通过同源搜索从橡胶树的转录组数据中电子克隆到一条长1 415 bp的cDNA,该序列包含一798 bp的ORF及47 bp的5′UTR和570 bp的3′UTR,命名为HbCAB1;在此基础上,采用PCR技术成功扩增了包括该ORF在内的915 bp的cDNA序列。序列分析表明,该基因预测编码265个氨基酸,理论分子量为28.15 ku,等电点为5.25;蛋白含有1个保守的捕光叶绿素a/b结合蛋白结构域,3个跨膜螺旋和1个C端螺旋,1个三聚化基序,以及多个叶绿素和类胡萝卜素结合位点;蛋白与蓖麻(Ricinus communis)、杨树(Populus trichocarpa)、橄榄(Canarium album)中同源蛋白的相似性都在95%以上,显示出基因进化的保守性。半定量RT-PCR分析显示,与稳定期叶片相比,HbCAB1在衰老期叶片中的转录水平显著下调。

Based on a EST sequence encoding a deduced polypeptide with high similarity to Arabidopsis CAB1,a 1415 bp cDNA was in silico cloned from the transcriptome data of rubber tree（Hevea brasiliensis Muell.Arg.）.The sequence designated as HbCAB1 contains a ORF of 798 bp with 47 bp 5 ＇UTR and 570 bp 3＇ UTR.Subsequently,a 915 bp cDNA sequence including this ORF was amplified and sequenced.Sequence analysis showed that HbCAB1 encodes a deduced protein of 265 amino acids with a theoretical molecular weight（Mw） of 28.15 kDa and isolectric point（pI） of 5.25;the protein contains a conserved light-harvesting chlorophyll a / b binding protein domain,three transmembrane helices and a C-terminal helix,a trimerization motif,as well as some chlorophyll and carotenoid binding sites.Similarity search reveals high amino acid sequence identity of CAB from different plants.For example,the similarity of HbCAB1 shares a similarity of more than 95% with the homologous protein in castor（Ricinus communis）,poplar（Populus trichocarpa）,or olive（Canarium album）.Semi-quantitative RT-PCR analysis showed that HbCAB1 exhibits significantly lower expression in senescent leaves than the stable leaves.