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利用CODEHOP和RACE方法,从珍稀观赏植物金花茶(Camellia nitidissima)花瓣中克隆得到了β-胡萝卜素环羟化酶(β-carotene hydroxylase,BCH)基因的cDNA全长,命名为CnBCH。碱基序列分析结果表明,该CnBCH基因全长1 089 bp,包含58 bp的5’非翻译区(untranslated regions,UTR)、105 bp的3’UTR和927 bp编码308个氨基酸的开放阅读框。生物信息学分析表明,该基因编码的蛋白质为不稳定亲水性蛋白,分子量为34.42 k D,无信号肽,含有4个跨膜结构域,一个脂肪酸羟化酶超家族(FA_hydroxylase super family)功能结构域以及BCH功能结构域(PLN02601);CnBCH二级结构以α-螺旋为主,其次为无规则卷曲,β-折叠所占比例最少。氨基酸序列比对分析结果显示,CnBCH与茄科、蔷薇科等植物BCH蛋白同源性都在70%以上,与柿树(Diospyros kaki T.)BCH同源性最高。本研究为进一步了解CnBCH基因的功能及其在金花茶花瓣类胡萝卜素合成中的作用提供了帮助。
The full-length cDNA of β-carotene hydroxylase (BCH) gene was cloned from the petals of the rare ornamental Camellia nitidissima by CODEHOP and RACE methods and named as CnBCH. The nucleotide sequence analysis showed that the CnBCH gene was 1 089 bp in length and contained 58 bp 5 ’untranslated regions (UTRs), 105 bp 3’ UTR and 927 bp open reading frame encoding 308 amino acids. Bioinformatics analysis showed that the protein encoded by this gene was an unstable hydrophilic protein with a molecular weight of 34.42 kD, no signal peptide, four transmembrane domains, a function of FA_hydroxylase super family Domain and BCH functional domain (PLN02601). The secondary structure of CnBCH is mainly α-helix, followed by irregular curl, with the least proportion of β-sheet. The results of amino acid sequence alignment showed that the homology of BCH protein between CnBCH and Solanaceae and Rosaceae was more than 70%, and the homology was the highest among BCH from Diospyros kaki T. This study is helpful to further understand the function of CnBCH gene and its role in the synthesis of Camellia petals.