家兔MT-I基因克隆及其在大肠杆菌中的表达与分离

Cloning, Expression and Purification of Rabbit Metallothionein-I Gene in Escherichia Coli

采用 RT- PCR方法扩增镉诱导后的家兔肝脏金属硫蛋白 - I(Metallothionein- I,MT- I)基因的 c DNA全长 ,克隆入原核融合表达载体 p QE4 0 ,转化大肠杆菌 M15。菌落印迹法检测阳性菌株 ;Western blotting分析重组融合蛋白的表达方式 ;经 SDS- PAGE电泳后 ,Im age Master VDS software分析融合蛋白诱导表达条件 ;并采用 Ni-NTA agarose纯化融合蛋白。结果发现 ,重组融合蛋白在原核细胞中表达存在可溶和不可溶 (包涵体 )两种形式 ,表达量随 IPTG诱导时间延长而增加 ,9h达高峰 (占菌体不溶性蛋白总量的 5 7.4 % ) ,经 Ni- NTA亲合层析纯化得到重组融合蛋白 。

The cDNA encoding the rabbit metallothionein-I was amplified by RT-PCR from the rabbit liver induced by cadmium and cloned into prokaryotic fusion expression vector pQE40.Then it was transformed into Escherichia coli M15. Positive expression clones were detected by colony blotting. Target protein solubility was determined by Western blotting analysis.The optimal induction condition of the level of protein expression with IPTG induction was established by SDS-PAGE electrophoresis and ImageMaster VDS software analysis. The fusion protein can be purified from lysates with Ni-NTA agarose. We found that the fusion protein with apparent molecular weight 32 KD existed in two ways: soluble and insoluble in Escherichia coli. After 1mM IPTG induction, the level of expression of the fusion protein increased with the prolongation of induction time and reached a peak in 9 h by ImageMaster VDS software analysis, accounting for 57.4% of all the insoluble protein. The purified fusion protein was obtained by Ni-NTA affinity chromatography.This fusion protein can be used in further studies on the preparation of MT-I protein and development of protein product.