Improvement of recombinant streptokinase production in E.coli

Streptokinase is one of the antigenic proteins secreted by streptococcus pyogenes. This protein has an important role in bacterial pathogenesis. The aim of this study was to produce recombinant forms of this enzyme so that the product would change in accordance with changes in the media.

In this experimental study, we amplified the streptokinase gene by polymerase chain reaction (PCR) method. After extraction, it was sub-cloned to prokaryotic expression vector pET32a. pET32a-Ska was transferred to E.coli BL21-DE3-plySs strain. Protein production was induced by IPTG and optimization of culture media and OD of bacteria. The recombinant protein was extracted by Ni-NTA and its concentration was measured by Bradford assay. Western- Blot analysis was used to verify the recombinant protein.

The nucleotide sequence of the amplified gene was the same as streptokinase gene of the streptococcus pyogenes. The production of recombinant streptokinase by induction of plasmid pET32a-Ska was done by IPTG. The recombinant streptokinase had the same antigenic properties as natural streptokinase. The largest amount of recombinant protein was produced in bacteria concentrations with OD = 0.8. Also, the production of the recombinant protein was higher in media with no glucose.

Changes in culture media can increase the production of recombinant proteins in host bacteria. The presence of nutrients, such as glucose, alone not only can not increase the amount of production but it might even decrease it.