mompS-linker-flaA融合基因原核表达载体的构建及诱导表达

Construction of a prokaryotic expression vector carrying mompS-linker-flaA fusion gene and its expression in E.coli

目的在嗜肺军团菌主要外膜蛋白S基因(mompS)和鞭毛亚单位蛋白基因(flaA)基因间加入一段柔性链接头(Linker),以构建mompS-Linker-flaA融合表达载体,并使其在大肠杆菌中表达。方法以嗜肺军团菌1型DNA为模板,PCR分别扩增获得嗜肺军团菌mompS基因和flaA基因,与带有硫氧还蛋白(Trx)基因的高效原核表达质粒pET32a(+)定向重组,构建含mompS-Linker-flaA基因的重组质粒pET-LpSLF,经限制性核酸内切酶酶切鉴定、PCR和核酸序列分析后,以IPTG诱导表达Trx-MOMPS-Linker-FlaA融合蛋白,用SDS-PAGE及Westernblotting进行鉴定。结果限制性核酸内切酶酶切鉴定、PCR和核酸序列分析表明,我们扩增出了嗜肺军团菌906bp的mompS及1440bp的flaA基因,成功构建了重组质粒pET-LpSLF,SDS-PAGE及Westernblot分析显示重组质粒pET-LpSLF在原核系统中得到了表达。结论嗜肺军团菌mompS-Linker-flaA基因在大肠杆菌中得到了表达,为进一步从分子水平研究其免疫原性、免疫保护性及其在临床诊断上的应用价值提供研究基础。

Objective To construct the fusion expression vector ofLegioneUa pneumophila mompS andflaA genes linked with a flexible chain for expression in E.coli. Methods TheflaA gene, an flagellum subunit gene of LegioneUa pneumophila, and mompS gene that encodes an major outer membrane protein of Legionella pneumophila, were amplified from the DNA of Legionella pneumophila by PCR and cloned into the prokaryotic expression vector pET32a （＋） containing thioredoxin gene Trx. Following analysis of the recombinant plasmid （pET-LpSLF） with restriction endonuclease digestion, PCR and DNA sequencing, the expression of pET-LpSLF was induced with IPTG and the expressed fusion protein Trx-MOMPS-FIaA was examined with SDS-PAGE and Western blotting. Results The results of restriction endonuclease digestion, PCR and DNA sequencing analysis showed that theflaA gene （1 440 bp） and the mompS gene （906 bp） were successfully amplified from Legionella pneumophila DNA, and the recombinant plasmid pET-LpSLF was constructed and expressed in E.coli as demonstrated by SDS-PAGE and Western blotting. Conculsion The fusion expression vector of mompS andfloA genes linked with a flexible chain has been successfully constructed and allows efficient expression of mompS-linker-flaA gene in E.coli, which enables further study of the immunogenicity and immunoprotection of Legionella pneumophilca.