[Construction of prokaryotic expression vector and expression of human beta defensin 4 gene]

Human beta defensin 4 is a small cationic peptide with a broad range of antimicrobial activity. It plays an important role in innate immunity of human body, especially in mucosal and epithelial defense. In this study, the full-length encoding gene of HBD4 was synthesized by overlap extension polymerase chain reaction and inserted into cloning vector pMD18-T. The gene encoding mature peptide of HBD4 was amplified by PCR and cloned into prokaryotic expression vector pGEX-4T-2. Then pGEX-4T-2/mHBD4 was transformed into E. coli DH5 alpha, which was induced by isopropy-beta-D-thiogalactoside (IPTG). The identification was made by means of endonuclease digestion, DNA sequencing, sodium dodecyl sulphate-polyacrylamine gel electrophoresis (SDS-PAGE). The results showed that the synthesized gene and cloned gene were identical to the HBD4 gene sequence registered in GenBank and were successfully cloned into cloning vector pMD18-T and prokaryotic expression vector pGEX-4T-2. After IPTG induction, the GST-HBD4 fusion protein was successfully expressed in E. coli.