The effect of cytoplasmic chaperones co-expression with recombinant human nerve growth factor in E. coli

Nerve growth factor (NGF) is a neurotrophic factor that is functional in survival, maintenance and differentiation of peripheral and central nervous system cells. This protein has three subunits that its beta subunit has main activity. According to scientific studies, it can be used as a therapeutic agent in treatment of many diseases such as peripheral neuropathy associated with diabetes, Alzheimer's disease, Parkinson's disease, skin disease and so on. Prokaryotic expression of recombinant NGF should be done in the periplasmic space because of its oxidative envoronment. It is worth noting that co-expression of cytoplasmic molecular chaperones can facilitate the secretion of the recombinant proteins to the periplasmic space and also enhance the protein solubility. In this study, the effect of cytoplasmic chaperones of GroEL / GroES, DnaK / DnaJ, GrpE, Trigger Factor (TF) on the periplasmic production of recombinant NGF protein was studied. For this purpose, β-NGF subunit was expressed in pET39b(+) expression vector simultaneously with chaperone plasmids pG-Tf2, pTf16, pGro7, pKJE7 and pG-KJE8 in E. coli DE3 strain. The results showed that in the presence of TF chaperone (pTf16 plasmid), the total protein and periplasmic production increased. Also, the DnaK/DnaJ and GroEL/GroES chaperones (pG-KJE8 plasmid) have also increased the production to some extent.; while the expression of GroEL/ GroES (pGro7) or DnaK / DnaJ (pKJE7) had no effect on protein expression. Also treatment of PC12 cell line with recombinant β-NGF showed differentiation to nerve cells which indicates that the produced protein is fully functional.