Improved Production of Recombinant Human Activin A in Escherichia coli

Activin A is a member of transforming growth factor β (TGF-β) superfamily. It plays numerous roles in the body such as cell growth regulation and differentiation, wound repairing and modulation of inflammatory responses. More importantly, it can be used as a therapeutic agent; so recombinant production of it, especially in the periplasm of E. coli as an economical bacterium is of great value. The aim of this study is large- scale production of activin A with a correct structure. For this purpose, three strategies were used. First, an efficient and appropriate signal peptide, modified Iranian Bacillus Licheniformis α-amylase signal peptide, was selected to secrete activin A to the E. coli periplasm as a suitable environment for correct protein folding. Second, cytoplasmic chaperones, Dnak, DnaJ, GroEL/ GroES, TF (trigger factor) were expressed simultaneously with activin A. Finally, the agitation rate was optimized to achieve the highest production of Activin A at the bioreactor scale. Our results indicated that by the co-expression of TF with activin A and using agitation rate of 1000 rpm maximum expression of activin A in E. coli was obtained. More importantly, based on the CD spectroscopy results and bioassay test the produced activin A had the correct secondary structure as the commercial type and was fully active.