参环毛蚓MT-2基因及启动子的克隆研究

Cloning of MT-2 gene and its promoter in Pheretima aspergillum

目的揭示参环毛蚓MT-2基因的转录调控机制,为今后采用基因工程技术改良参环毛蚓重金属富集性状奠定基础。方法根据已知的MT-2c DNA序列,设计特异引物,通过PCR扩增参环毛蚓MT-2基因的编码区基因组序列,扩增产物经测序后自行比对分析。基于该序列设计3条特异引物,采用基因步移技术克隆其上游的启动子序列,同时运用Promoter Prediction在线软件分析预测其顺式元件。结果经PCR扩增、测序后获得2 826 bp MT-2基因编码区序列,将该序列与已知MT-2 c DNA序列(登录号为KC787373.1)进行比对,发现MT-2编码区由4个外显子和4个内含子组成。基因步移技术克隆得到1 534 bp的启动子序列,经Promoter Prediction在线软件分析,结果显示该序列不仅含有TATA-box、CAAT-box等核心启动子软件,还具有3个特异响应重金属参与调控MT-2表达的MRE元件。结论参环毛蚓的MT-2基因能被重金属诱导表达,MT-2基因转录水平的金属调控是通过MT-2基因启动子区的金属调控元件MRE来实现的。

Objective To lay a foundation for attenuating the heavy metal accumulation in Pheretima aspergillum by means of genetic engineering technology in further research, we revealed the transcriptional regulation mechanism of MT-2 gene. Methods The coding sequence ofMT-2 gene was amplified by PCR with specific primers, which were designed according to their known cDNA sequences, and the outcomes were contrastively analyzed after the sequencing process. Prior to the isolation of 5＇ promoter sequence by genome walking technology, three specific primers were designed based on MT-2 cDNA sequence. Meanwhile, the cis-acting elements of MT-2 gene were analyzed by Promoter Prediction online software. Results After PCR and sequencing processes, a 2 826 bp coding sequence of MT-2 gene were obtained, four exons and four introns were found to compose the coding area by comparing with the known MT-2 cDNA sequence （accession No.KC787373.1）. Besides, after genome walking and Promoter Prediction online analysing, a 1 534 bp promoter region of MT-2 was isolated, which contained not only CAAT box, TAAT box, and other core promoter elements, but also three MRE elements which specifically response to heavy metal involved in regulating the MT-2 expression. Conclusion The expression of MT-2 gene in P. aspergillum can be induced by heavy metal, and the transcriptional level is achieved by MRE regulatory elements located in MT-2 gene promoter region.