The expression of gene related to salt tolerance from Sinorhizobium meliloti 042BM in Escherichia coli and purification of its fusion protein
苜蓿中华根瘤菌与耐盐有关基因rstA在大肠杆菌中的高效表达及其产物的纯化

A 1.9kb DNA fragment related to salt tolerance ofS.meliloti strain 042BM containing two open reading frames were obtained by PCR amplication and ligated into shuttle vector pBBR1-MCS2. The complementation experiment showed that ORF2 is related to salt tolerance and named asrstA gene. Then the gene was cloned into the expression vector pThio-HisA, B and C, respectively, and recombinant expression vectors pGSA, pGB and pGC were constructed,and transformed intoE.coli Top10. Inducing by IPTG and analyzing with SDS-PAGE, the fusion protein encoded by pGSA was obtained,and it is 36% content of whole cell protein. It was isolated and purified by affinity chromography on ProBond TM , and the inclusion body precipitated by saturated sulfate ammonium, and 95% purity of fusion protein was obtained. The final product displayed a single band with a corresponding molecular weight 43kD in SDS-PAGE, and was verified by the Western blot.