叶子花花色DOD基因全长cDNA克隆与序列分析

摘要

The RNA of Bougainvillea spectabilis Willd.bracts were extracted , and the 4, 5-DOPA dioxygenase ( DOD ) gene full-length cDNA was cloned by RACE technique .The full length of the cDNA was 1 059 bp, open reading frame ( ORF) was located between the 56-802 bp,which encoding 249 amino acid residues .According to bioinformatic analytical results of the amino acid sequence , there was 4,5-DOPA dioxygenase conserved domain in this sequence , and the molecular weight of the protein com-ponent was 27.94 kD.The pI was 5.48, and it was stable protein.The prediction of the secondary structure showed that there were 8 α-coils, 8 β-sheets, and 20β-turns in it.Most of the amino acid residues were hydrophilic , yet no signal peptide and transmem-brane structure was found .The blast results showed that as the differences of the species increased , the similarity of the DOD was decreased .It is indicated that DOD gene was quite conserved in betalain plants by discovering the phenomenon that anthocyanins metabolism and betalain metabolism were different and could not coexist in one plant .%以叶子花花苞为材料，运用RACE技术克隆出了叶子花苞片中的多巴双加氧酶基因cDNA全长，探讨叶子花花色变化机理和甜菜色素代谢途径。该序列长度为1059 bp，开放阅读框位于56-802 bp之间，共编码249个氨基酸残基。对该氨基酸序列进行生物信息学分析，结果表明该氨基酸序列具有多巴双加氧酶保守结构域，所组成的蛋白分子量为27．94 kD，等电点为5．48，是稳定蛋白。对其二级结构进行预测：该序列具有8个α螺旋、8个β转角、20个β折叠，其序列大多是由亲水性氨基酸残基组成，不具有跨膜结构和信号肽。对该氨基酸序列进一步的Blast比对，发现组成多巴双加氧酶的氨基酸序列因植物种类而异，且亲缘关系越远，差异越大，结合花青素与甜菜色素代谢途径的不同和在自然界中不能共存的现象，表明多巴双加氧酶基因在生成甜菜色素植物中具有独特的保守性。