单环刺螠转录因子基因Sp8的克隆、原核表达和重组蛋白纯化

Cloning of Transcription Factor Gene Sp8 of Urechis unicinctus,its Expression in E.coli and Purification of Recombinant Protein

转录因子Sp是一类广泛存在的锌指蛋白超家族成员,可与某些基因的上游调控序列结合,参与基因的转录调控。本研究采用同源克隆和RACE技术,获得单环刺螠的Sp8的全长cDNA,该序列长1 913bp,开放阅读框1 521bp,编码506个氨基酸;将其开放阅读框cDNA克隆到原核表达载体pET28a中,并转化大肠杆菌BL21(DE3)感受态细胞,在37℃条件下,经1mmol/L IPTG诱导表达4h,获得以包涵体形式存在的重组蛋白pET28a-SP,使用8mol/L尿素溶解包涵体,并通过镍离子金属螯合柱纯化获得重组蛋白,SDS-PAGE分析该蛋白的分子量约为50kD。Sp8蛋白体外表达的成功将为研究单环刺螠相关基因的转录调控打下基础。

The members of Sp gene family of vertebrates encode evolutionarily conserved proteins which are characterized by 3 zinc finger motifs and involved in a variety of developmental processes. In this stud- y, we isolated a full length eDNA of Sp8 gene from Urechis unicinctus with degenerate PCR and rapid am- plification of eDNA end methods. The eDNA was 1,913 bp in length, which contained an open reading frame （ORF） （1,521 bp in length） encoding 506 amino acid residules. A recombinant plasmid pET28a- Sp8 was constructed by inserting Sp80RF into pET28a and transferred into E. coli BL21 （DE3）. It was found that Sp8 was expressed in E. coli, forming inclusion bodies as was proved by SDS-PAGE analysis after lmmol/L IPTG induction at 37~C. Recombinant protein forming inclusion bodies was dissolved in 8 mol/L urea and purified with Ni^2＋-NTA affinity chromatography. It was found that the recombinant pro- tein has a molecular mass of 50 000 Da. The successful prokaryotic expression of Sp8 will provide a base for the research of transcription regulation of genes related to sulfide metabolism in U. unicinctus.