Cloning And Expression Of Escherichia Coli O157:H7 Stx 2B Subunit

Aim To clone,identify and express the gene of Shiga-like toxin 2B of EHEC O157:H7.Methods A pair of primers was designed based on the Stx2B subunit gene sequence of EHEC O157:H7.The stx2b gene was amplified from EHEC O157:H7 chromosome by PCR and then cloned into pMD18-T vector.Thereafter,the gene was cut from pMD18-T vector and cloned into prokaryotic expression plasmid pET-28a vector.Then the recombinant plasmids were transformed into E.coli BL21(DE3) and the transformed host strain induced by IPTG.The expression protein was detected by SDS-PAGE and Western-blot analyses.Results The stx2b gene was successfully cloned into pMD18-T and pET-28a vectors.The expressed protein was identified by SDS-PAGE and Western blot.The molecular mass(Mr) of the expressed product was about 7.5 kDa;the expression rate was about 40%.Conclusion The stx2B has been successfully expressed in prokaryotic expression system.