The Recombinant Expression and Receptor-binding Activity of the B Subunit of Shiga-like Toxin Type Ⅱ / 中国生物工程杂志

ABSTRACT

Objective:To express the B subunit of Shiga-like toxin type Ⅱ,and analyze its expression form and receptor-binding activity.Methods:The slt2b gene was obtained from EHEC O157∶H7 by PCR,and cloned to the expression vector pET22b(+).The genetically engineered bacteria pET22b(+)-stx2B/BL21 expressed the recombinant StxB after induced with IPTG.The renatured inclusion bodies were purified by ion exchange chromatography.The expression form of rStx2B was investigated by denaturing and native electrophoresis.The receptor-binding activity was confirmed by fluorescence detection and flow cytometer.Result:The constructed genetically engineered bacteria expressed the rStx2B at a high level.The purified protein was obtained after denaturation,renaturation and ion exchange chromatography.According to the denaturing and native electrophoresis,the rStx2B was expressed in a dimmer form,which consists of two monomers cross linked with disulfide bridge.The rStx2B showed good receptor-binding activity by Hela-binding assay.Conclusion:The genetically engineered bacteria were constructed successfully.The receptor-binding activity of rStx2B was independent of the pentamers.