甘薯贮藏蛋白基因启动子和信号肽编码区克隆及序列分析

Cloning and Sequence Analysis of the Promoter and Signal Peptide coding Region in Sporamin Gene from Ipomoea batatas

根据已知的甘薯块根贮藏蛋白 A基因序列 ,设计和合成了两对 PCR引物 ,从南薯 88基因组中分别扩增出该基因的启动子和启动子加信号肽编码区两种 DNA片段 ,并测定了它们的 DNA序列。将测定的序列与 Gen Bank中的甘薯贮藏蛋白基因的相应序列进行同源性分析 ,结果发现 ,其中既有与Gen Bank中甘薯贮藏蛋白基因启动子完全相同的片段 ,也有发生了较大变异的片段 ,这些变异涉及到调控表达的顺式作用元件。在信号肽编码区 ,虽存在碱基序列变异 ,但比启动子区更保守 。

Two DNA fragments, promoter (fragment 1) and promoter with signal peptide coding sequence (fragment 2) of sporamin from sweet potato Nahshu 88, a widely cultivated variety in China, were amplified by the polymerase chain reaction (PCR). The amplified fragments were cloned and then sequenced. Sequence comparison showed that the fragment 1 sequence was almost identical to the corresponding region of sporamin gene, gSPO A1, but different from that of gSPOR5 31. The sequence of fragment 2, including some cis regulatory elements, was different from the corresponding region of gSPO A1 and gSPOR5 31. Comparison of signal peptide coding sequence among fragment 2, gSPO A1 and gSPOR5 31 showed 8 nucleotides changed, which appeared in the region of pre segment, not in the region of pro segment. These results indicated that the 5′ flanking region of sporamin genes was much conserved, but there was some variation, especially in the promoter region, which maybe play some role in gene expression.