烟草类胡萝卜素双加氧裂解酶基因的克隆与序列分析
Cloning and Sequence Analysis of Carotenoid Cleavage Dioxygenase Gene from Nicotiana tabacum
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摘要: 为揭示类胡萝卜素双加氧裂解酶基因(CCDs)在烟草生长发育过程中的功能,通过RT-PCR技术克隆到烟草的类胡萝卜素双加氧裂解酶4基因(NtCCD4),编码区1806 bp,编码601个氨基酸,基因序列提交NCBI,GenBank登录号为JF947192。根据氨基酸组成对NtCCD4基因编码蛋白的疏水性/亲水性、蛋白结构及进化关系等进行预测和分析。结果表明:烟草NtCCD4基因编码的蛋白分子量为65936.3 Da,等电点为6.58,定位在叶绿体膜上,为一个稳定的亲水性蛋白;二级结构预测显示此蛋白结构以无规则卷曲(57.4%)为主,α螺旋(13.31%)和β转角(6.61%)所占比例相对较少;进化分析表明NtCCD4是类胡萝卜素双加氧裂解酶基因(CCDs)家族中的一个成员,与其他物种的CCD4蛋白比较显示NtCCD4编码的蛋白含有多个保守区域,其中4个组氨酸残基是组成蛋白功能域所必须的,它们与Fe2+结合共同组成蛋白酶的活性中心。Abstract: In order to reveal the function of carotenoid cleavage dioxygenases (CCDs) in the growth and development of tobacco plants, a CCD4 (NtCCD4) gene was cloned from Samsun oriental tobacco by RT-PCR. According to sequence analysis, with a coding sequence of 1806 bp in length the gene encoded 601 amino acids. The sequence was submitted to NCBI and its GenBank accession number was JF947192. Various bioinformatics softwares were adopted to analyze and predict physicochemical properties, advanced structure and biological function of NtCCD4 protein. The results showed that the molecular weight and isoelectric point of the encoded protein were 65936.3 Da and 6.58, respectively. The protein located on chloroplast membrane and was a stable and hydrophilic protein. The secondary structure prediction indicated that the protein structure was composed mainly of random coil (57.4%) and alpha helixes (13.31%), beta turn (6.61%). The phylogenetic tree analysis showed that NtCCD4 belonged to CCDs family containing numerous conserved domains, of which the 4 histidine residues were necessary for composing the functional domain and constructed the active center of the protein by combining with Fe2+.
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