【摘要】 目的克隆幽门螺杆菌(Hp)尿素膜通道基因(ureI)和构建能表达UreI蛋白的原核表达工程菌,并初步研究产物的表达特性和免疫特性。方法用PCR方法从Hp基因组中克隆ureI基因,构建原核表达重组质粒pET32a/ureI,双酶切和测序鉴定正确后,重组质粒转染大肠杆菌BL21+(DE3),构建高效表达UreI的工程菌BL21+/UreI。不同温度条件下用1.0mmol/LIPTG诱导重组蛋白表达,用SDS-PAGE和Gel-ProAnalyzer4分析重组蛋白的表达,并用Westernblotting对其免疫原性进行分析。结果克隆到约650bp的基因片段,测序结果与GENBANK中对应菌株的ureI序列100%同源,与其他Hp的序列同源性不低于98.5%。工程菌BL21+/UreI含完整的ureI基因。在37℃、1.0mmol/LIPTG诱导14h后,重组蛋白表达量可达菌体总蛋白的20.2%。分析表明重组蛋白主要以包涵体形式表达,经免疫印迹证实该重组蛋白有一定的免疫反应性和特异性。结论成功构建了HpureI基因的原核表达载体,该载体可高表达有免疫特性的重组蛋白,为进一步研究Hp在胃的定植机制和抗Hp新药奠定了基础。更多还原

【Abstract】 Objective To clone the urea membrane channel gene (ureI) from Helicobacter pylori (Hp) for its expression in E.coli, and evaluate the expression conditions and immunological features of the fusion protein. Methods ureI gene cloned by PCR from Hp was inserted into the plasmid pET32a (+) to construct the recombinant plasmid pET32a/ureI, followed by identification by BglII and HindIII digestion and sequencing. E.coli BL-21+(DE3) was transformed with pET32a/ureI to obtain the engineered bacterium BL21+/UreI, which was cultured at different temperatures and induced with 1.0 mmol/L IPTG for expression of the recombinant protein. The expressed proteins were identified by SDS-PAGE and analyzed by Pro-gel analyzer 4.0. Western blotting was performed to evaluate the immunogenicity of the expressed protein. Results The cloned gene fragment was about 650 bp in length, and BglII and HindIII digestion of pET32a/ureI yielded a 650-bp band. Sequence analysis revealed that the cloned ureI gene contained 646 bp without reading frame alterations. Comparison against GenBank indicated a homology of 100% of the cloned gene with ureI gene of the corresponding Hp strains, and also one no less than 98.5% with ureI gene from other strains. The engineered E.coli BL21+/UreI could express recombinant UreI (rUreI) with His tag, and the target protein accounted for 20.2% of the total bacterial proteins after 1.0 mmol/L IPTG induction of the bacterium at 37 ℃ for 14 h. SDS-PAGE and Western blotting showed that the recombinant UreI protein was produced mainly in the inclusion bodies and fused with his-tag (rUreI/his), which could react with human anti-Hp and mAb to his tag but not with mAb to Hp UreB. Conclusions We have successfully cloned ureI gene and constructed the prokaryotic expression plasmid for efficient rUreI expression, and the fusion protein rUreI/his expressed in the inclusion bodies can react specifically with both Hp antibody and his-tag antibody.更多还原