目的构建hITF毕赤酵母分泌型表达载体,表达重组hITF,为功能研究奠定基础。方法通过PCR获得hITFcDNA片段,将目的基因插入酵母表达载体pGAPZαA分泌信号下游,得到重组载体pGAPZαA-hITF。BspHⅠ线性化后氯化锂转化进入X-33,Zeoc in筛选转化酵母菌,PCR鉴定目的基因。阳性转化子经摇瓶表达,取上清TCA沉淀后做Tric ine SDS-PAGE分析及W estern b lot检测。结果经测序及PCR证实,hITFcDNA准确插入酵母表达载体pGAPZαA中,氯化锂转化后,重组载体通过同源重组整合进入酵母基因组中。Tric ine SDS-PAGE分析证明hITF的分子量约为10×103,W estern b lot分析表明,表达蛋白具有良好的抗原性和特异性。结论成功构建出酵母表达载体pGAPZαA-hITF,获得重组hITF,为深入研究hITF奠定了基础。
Objective:To construct a Pichia pastoris (P. pastoris) expression vector of human intestinal trefoil factor (hITF) and study its expression and purification procedures. Methods:hITF gene encoding mature peptide was modified with a polyhistidine tag sequence at the N-terminal, and then inserted into the P. pastoris expression vector pGAPZαA at the downstream of theα-mating factor signal. After gene sequencing, the recombinant pGAPZαA-hITF was transformed into the P. pastoris strain X-33 with lithium chloride. rhITF was induced to constitutively express in shake flask, and then analyzed with Tricine SDS-PAGE and Western blotting. The obtained rhITF was isolated from the cultured supernatants by ammonium sulfate precipitation, Ni-NTA affinity chromatography, and ultrafiltration. Results:The correctness and integrity of rhITF were identified by restriction digestion and gene sequencing. rhITF was successfully expressed to 50 mg/L as a secretive protein. After purification, the purity was above 95%. Tricine SDS-PAGE and Western-blot analysis showed that rhITF presented as a single band with a molecular weight of 10 kDa, a little larger than 7 879 Da as assayed by mass spectrometry analysis. Conclusion: hITF P. pastoris expression vector is successfully constructed and rhITF is expressed in P. pastoris at commercially relevant level. This research lays foundation for the further functional studying of hITF.
