人源性神经营养素-6成熟肽基因融合表达载体的构建及表达产物的纯化

为了得到人源性神经营养素-6(N eurotroph in-6,NT-6)成熟肽片段,本研究以经测序鉴定的人源性NT-6 cDNA为模板,通过聚合酶链式反应(Po lym erase cha in reaction,PCR)扩增得到NT-6蛋白成熟肽编码区基因片段;将该基因克隆到融合表达载体pGEX 1-λT,构建重组原核融合表达质粒pGEX-NT-6;在异丙基-β-D-硫代半乳糖苷(Isopropy l-βD-th ioga lactos ide,IPTG)诱导的条件下,观察融合蛋白在大肠杆菌JM 109中的表达情况;利用蛋白回收试剂盒对表达产物进行纯化。结果表明经PCR扩增后,得到一分子量为460 bp左右的片段;含有该片段的重组质粒经电泳及双酶切鉴定表明,所得到的重组质粒即为含有目的片段的pGEX 1-NT-6;与带有pGEX 1-λT质粒的细菌相对照,pGEX 1-NT-6质粒转化的大肠杆菌JM 109,在IPTG诱导下表达了特异性的融合蛋白,该蛋白分子量为41 KD。获得的融合蛋白经凝血酶酶切后,得到了分子量大约为15 KD的NT-6成熟肽。本研究成功构建了人源性NT-6成熟肽编码区基因融合表达载体,并纯化了其表达产物,为研究人源性NT-6的生物学功能奠定了基础。

Construction of Fusion Expression Vector of Human-derived Neurotrophin-6 Gene Encoding Mature Peptide and Purification of Its Expressed Product

To get the mature peptide of human-derived neurotrophin-6 (NT-6), NT-6 gene encoding mature peptide was amplified by PCR, using the NT-6 cDNA that had been cloned as templet. The gene encoding mature peptide of NT-6 gene was cloned into pGEX1-lambdaT plasmid to construct the fusion expression vector. Expression of fusion protein in Escherichia coli was defected after induction by isopropyl beta-D-thiogalactoside(IPTG). The mature peptide of NT-6 was collected with GST fusion protein purifying kit. It was shown that a fragment of 460bp was gained by PCR. With the techniques of double-cleave and electrophoresis, the recombinant vector was identified as pGEX1-NT-6. The recombinant vector pGEX1-NT-6 transformed Escherichia coli expressed fusion protein of 41KD after induction by IPTG. Cleaved by thrombin, the mature peptide of NT-6 was obtained; its molecular weight was about 15KD. The cloning and expression of human-derived NT-6 gene encoding mature protein has provided a basis for further studies on the function and clinical application of NT-6.