【摘要】 为在大肠杆菌中高效表达乳酸片球菌素(PED),按照美国国立生物技术信息中心公布的PED基因序列设计合成引物,以乳酸片球菌基因组DNA为模板,用多聚酶链式反应扩增PED结构基因特异片段,构建编码组氨酸标记硫氧还原蛋白融合PED的重组表达质粒pET32c-PED,并转化大肠杆菌BL21(DE3)。在异丙基硫代半乳糖苷诱导后融合蛋白以包涵体形式表达,表达量占菌体总蛋白的28%。经镍亲合层析纯化的融合蛋白用肠激酶裂解,再经超滤纯化,可得78%的收率。融合蛋白没有抗粪肠球菌细菌素活性,被分开的PED恢复了抑菌活性。更多还原

【Abstract】 To effectively express pediocin PA-1(PED)in Escherichia coli,the primers specific for PED coding sequence is designed and synthesized according to the National Center for Biotechnology Information.The gene fragment of PED is amplified from genomic DNA of pediococcus acidilacticii LH31 by polymeras chain reaction.The plasmid pET32c-PED,encoding PED fused with His-tagged thioredoxin protein,is constructed and introduced into escherichia coli BL21(DE3)strain.The fusion protein is expressed in inclusion bodies counting 28% of total cellular proteins in the strain after induction of isopropyl-β-D-thiogalactopyranoside(IPTG)and purified by nickel-nitrilotriacetic acid(Ni-NTA)metal affinity chromatography.For the recovery of biologically active PED,the purified fusion protein is cleaved by enterokinase and the liberated PED is finally purified by ultrafiltration with a 78% yield.The fusion protein,which does not have bactericidal activity against enterococcus faecalis,is cleaved by enterokinase and the cleaved PED recovers its own bactericidal activity.更多还原