Does SCP-2 promote the expression of foreign proteins in Escherichia coli?

Abstract:

Expression of foreign proteins in host organisms usually results in the development of insoluble, inactive proteins. Further, these proteins have a tendency to form aggregates termed inclusion bodies. However, the formation of inclusion bodies can be avoided by fusing the gene encoding the foreign protein to a highly soluble protein. In this report Sterol Carrier Protein-2 (SCP-2) is reviewed as a possible solubility tag. The experiment was carried out by fusing SCP-2 to one of two i nsoluble proteins, Green fluorescent protein (GFP) or a form of chloramphenicol acetyl transferase (CAT∆9). The protein fusion was then inserted into the vector pET-15b, transformed in Escherichia coli and the yield of actively expressed protein was measured. The results obtained from this study, as evaluated by PageBlue staining and  Western blot, are indicating that SCP-2 does not improve the solubility of GFP or CAT∆9. Nonetheless, the solubility of GFP has earlier been increased by fusing it to the solubility tag maltose-binding protein (MBP).  Producing more soluble forms of CAT∆9  have also been tested but without success. Therefore the conclusion drawn from this experiment is that SCP-2 does not work as a solubility tag, however more research must be performed to conclude this with certainty.