Optimization of expression and purification conditions of recombinant Hq001 protein in salivary glands of Haemaphysalis qinghaiensis
Objective To optimize the expression conditions(expression and induction conditions)and purification methods(non-denaturing and denaturing purification)of recombinant Hq001 protein in salivary glands of Haemaphysalis qinghaiensis.Methods The recombinant plasmid pET-30a-Hq001 was transformed into competent cells E.coil BL21(DE3),E.coil Rosetta(DE3)and E.coil ArcticExpress(DE3)pRARE2 respectively for the selection of an optimal expression strain.The final con-centration of IPTG(0,0.5,1.0mmol/L),induction temperature(20,25 ℃)and induction time(0,2,4,6,8 h)were optimized.The recombinant bacteria expressed under the ideal induction condition were homogenized by French press and the target protein was purified by passing through a Ni-NTA affinity chromatography column under either native(denaturation-renaturation-column chromatography)or denatured conditions(denaturation-column chromatography-renaturation).The purified products were analyzed by 12％SDS-PAGE.Results E.coil BL21(DE3)was proved to be the most suitable strain for the expression of recombinant Hq001 protein.The optimum induction condition was induction with 0.5 mmol/L IPTG for 4 h at 25 ℃.The target protein with a relative molecular mass of approximately 18 800 was obtained by non-denaturing purification method,and the size was consistent with the expectation.Conclusion The recombinant protein rHq001 in salivary glands of Haemaphysalis qinghaiensis can be obtained by the optimized expression conditions and purification methods.
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