人瘦素基因在胎盘中的分离鉴定及在大肠杆菌中的融合表达

IDENTIFICATION OF LEPTIN GENE FROM HUMAN PLACENTA AND ITS FUSION EXPRESSION IN ESCHERICHIA COLI

目的克隆人瘦素(leptin)基因,构建融合表达载体,实现在大肠杆菌中的高效表达。方法从人胎盘中提取RNA,利用反转录聚合链式反应(RT-PCR),克隆到人的leptin基因编码序列,对该基因片段进行T载体克隆、酶切和PCR鉴定,并且对其进行序列分析。将leptin基因插入到原核表达载体PET-28a中,转化大肠杆菌BL21(DE3)感受态细胞,利用IPTG进行诱导,对表达产物进行SDS-PAGE电泳分析,并利用脱氧胆酸钠对表达蛋白进行纯化。结果DNA序列分析表明,从胎盘中克隆的人leptin序列与文献报道的一致,酶切鉴定证实leptin基因正确地插入到了表达载体中,经IPTG诱导和SDS-PAGE电泳分析,人leptin基因在大肠杆菌中实现了高效融合表达,表达产物的分子量为20kD,经过纯化,得到了较纯的融合表达蛋白。结论从人胎盘中成功克隆了leptin基因,构建了原核表达载体,实现了在大肠杆菌中的高效表达,为进一步研究leptin的生物学功能奠定基础。

Objective To identify the sequence of eDNA of human leptin coding region, construct a prokaryotic expression vector, and express human leptin in E. coli. Methods RNA was extracted from human placenta tissue. Leptin gene was amplified from RNA by RT-PCR method. The PCR product was ligated with T vector. The ligation reaction was transformed to E. coli DH5α competent cells. The recombinant plasmid was checked by sequencing and restriction analysis. The human leptin gene was cloned into prokaryotic expression vector PET-28a and tranformed into E. coli BL21. The recombinant strain was constructed and induced by IPTG. The product was analyzed with SDS-PAGE and Western blotting. The expressive product was purified by sodium deoxycholate. Results Analysis indicated that the sequence of human leptin cDNA was the same with the reported sequence. Leptin gene was inserted into prokaryotic expression vector. The fusion protein expressed with high efficiency in recombinant E. coli BL21. The results of SDS-PAGE analysis indicated that the molecular weight of the fusion protein was about 20kD. Conclusion Hunam leptin gene was successfully identified from placenta. The leptin gene prokaryotic expression strain was constructed and a high expression of leptin was achieved in E. coli.