P4501A1基因Thr~(461)→Asn~(461)及Ile~(462)→Val~(462)突变载体的构建

目的构建P4501A1基因cDNAThr461→Asn461及Ile462→Val462突变载体,为进一步研究CYP1A1的功能和致癌机制奠定基础。方法根据人CYP1A1基因(GeneBankNM-000499)cDNA序列设计通用引物Pm3/Pm4和突变引物Pt15/Pt16;Pt17/Pt18,内含酶切位点和突变位点,先用Pm3/Pt16,Pm3/Pt18组成两对引物,以pGEM-T-CYP1A1质粒为模板进行第一轮扩增,获得上游1397bp片断,再用Pt15/Pm4,Pt17/Pm4组成两对引物以10ngpGEM-T-CYP1A1质粒为模板进行第二轮扩增,得到下游177bp片断。然后用Pm3/Pm4做引物以第一、第二轮扩增产物为模板进行第三轮扩增,获得的1·5kb扩增产物用1%琼脂糖凝胶分离并回收纯化,将纯化的PCR产物与pMD-T载体连接后转化大肠埃希菌DHα5感受态细胞,挑单克隆扩增、质粒抽提后进行酶切和测序鉴定。结果三轮PCR扩增得到的1·5kb片断,经内切酶BamHI和SalI消化和T7p和SP6通用引物进行双向测序,证实克隆的目的片段与GeneBank中人CYP1A1基因cDNA的序列同源性为99·9%,且包含两个设计的突变位点Asn461、Val462。结论本实验成功地构建了含突变位点Asn461、Val462的CYP1A1基因cDNA的片断。

Construction of Thr461→ Asn461 and He462→ Val462 mutation vector of P4501A1 gene

OBJECTIVE: To construct Thr461 --> Asn461 and Ile462 --> Val462 mutation vector of P4501A1 gene and to provide scientific base for deeply researching on the function of cytochrome 1A1 gene (CYP1A1) and the mechanism of carcinogenesis. METHODS: According to cDNA sequence of human CYP1A1 gene, universal primers (Pm3/Pm4) and mutant primers (Pt15/Pt16 and Pt17/Pt18) containing restriction enzyme site and mutation site were designed. The first set of primers involving Pm3/Pt16 and Pm3/Pt18 amplified a forward 1.5kb fragment from pGEM-T-CYP1A1 plasmid. The second set of primers involving Pt15/Pm4 and Pt17/Pm4 amplified a reverse 177-bp fragment from 10ng pGEM-T-CYP1A1 plasmid. The third set of primers involving Pm3/Pm4 amplified a 1.5kb fragment from the fomer PCR amplifications. The third PCR products were separated, purified and recovered from 1% agarose gel, then inserted into pMD-T vector. Subsequently the conjunct products were transformed into E. coil strain DH-5alpha., then the single clone was screened out and plasmids were extracted from such clone finally verified by restriction endonuclease analysis and sequencing. RESULTS: A 1.5kb fragment of tricycle PCR amplifications were digested by restriction endonucleases (BamHI and SailI) and sequenced bidirectionally by universal primers(T7p and SP6). The results verified that the cloned fragment including Asn461 and Val462 mutant site had 99.9% homology with the human cDNA of CYP1A1 gene in Genebank. CONCLUSION: The objective fragment containing Asn461 and Va462 mutant site with cDNA of the CYP1A1 gene has been successfully constructed in this experiment.