人补体受体1型活性片段SCR15-18在毕赤酵母中的表达、纯化及活性鉴定

Expression,purification and activity identification of SCR15-18 domain of human complement receptor 1 in Pichia Pastoris

目的实现人补体受体1型(complement receptor type 1,CR1)活性片段SCR15-18在毕赤酵母中的分泌表达。方法用PCR从原核表达质粒pET32a-sCR1-SCR15-18上扩增CR1-SCR15-18的编码基因,并克隆到毕赤酵母分泌表达质粒pPIC9,构建重组质粒pPIC9-CR1-SCR15-18,鉴定后测序;重组质粒电转化整合到毕赤酵母GS115基因组中,菌落PCR技术筛选阳性转化株;经摇瓶发酵和甲醇诱导,SDS-PAGE和Western blot鉴定目的蛋白的表达;Ni2+-NTA agarose亲和层析纯化目的蛋白,并用体外抑制补体溶血反应实验测定目的蛋白的生物活性。结果成功构建重组表达质粒pPIC9-CR1-SCR15-18;SDS-PAGE和Western blot证实目的基因在毕赤酵母中成功分泌表达;表达产物经镍柱快速纯化后,能够明显抑制补体的体外溶血。结论在毕赤酵母中成功实现了CR1-SCR15-18蛋白的分泌表达,该蛋白具有较高的抑制补体溶血的生物活性。

Objective To express the short consensus repeat 15-18 （SCR15-18） domain of human complement receptor 1 （ CR1 ） in Pichia pastoris as a secreted protein in order to found a base for large-scale industry fermentation. Methods The gene fragment of CR1-SCR15-18 was amplified by PCR from plasmid pET32a- sCR1-SCR15-18. The obtained sequence was subcloned into Pichia pastoris secretory expression vector pPIC9. After identification the recombinant plasmid pPICg-CR1-SCR15-18 was electrotransported into the yeast. Positive clones were identified using colony PCR. Positive recombinants were fermented in shake flaskes and induced with methanol. The recombinant proteins were identified with SDS-PAGE and Western blot analysis. After the recombinant protein was purified by Ni-NTA agarose metal chelate affinity chromatography, inhibiting complement hemolysis testing was used to detect the biological activity. Results Recombinant expression plasmid pPIC9-CR1-SCRIS-18 was successfully constructed. SDS-PAGE and Western blot analysis revealed that the target gene was successfully expressed in the yeast and the recombinant protein was successful secreted in the culture supernatant. After purification, the protein inhibited complement hemolysis in vitro. Conclusion CR1-SCR15-18 is successful expressed in Pichia Pastoris with high activity of inhibiting complement hemolysis.