[Expression of recombinant streptolysin O by escherichia coli]

ABSTRACT

Streptolysin O is an antigenic protein that is secreted by Streptococcus pyogenes. Streptococcal infections are diagnosed with anti streptolysin O. At present, streptolysin O is produced by vectors that have fusion protein. In this study we produced streptolysin O without fusion protein vectors. In this experimental study, we amplified Streptolysin O gene by Polymerase chain reaction [PCR] method and subcloned it to prokaryotic expression vector pET28a. Escherichia coli BL21-DE3-plySs were transformed with pET28a-SLO and gene expression was induced by IPTG. Then it was purified by Ni-NTA kit. The concentration of SLO was assayed by Bradford method. To confirm recombinant SLO Western Blot was used. The sequencing result was confirmed by Sanger method and was the same as SLO gene. Escherichia coli BL21 [DE3] pLysS was transformed with pET28a-SLO and gene expression was induced by IPTG. The expressed protein was purified by affinity chromatography by Ni-NTA resin. The concentration of purified protein was 100microg/ml. The integrity of product was confirmed by Western Blot analysis using a mouse anti streptolysin O. Our data showed that recombinant SLO protein can be produced by pET28a in Escherichia coli. This protein maintains its antigenic effect very well. Therefore, recombinant SLO has same epitopes with natural form of this antigen