Efficient Production of Recombinant Human Brain-Derived Neurotrophic Factor in Escherichia coli Through the Engineering of Its Pro-Region

Abstract

Thus far, no manufacturing process able to support industrialization has been reported for the recombinant human brain-derived neurotrophic factor (rhBDNF). Here, we described the setup of a new protocol for its production in Escherichia coli (E. coli) and its purification to homogeneity. A synthetic gene, codifying for the neurotrophin precursor, was inserted into an E. coli expression vector and transformed into BL21 (DE3) strain. The recombinant protein accumulates, at high yields, into inclusion bodies. With the developed strategy, more than 50% of the precursor can be refolded. The protein is successively digested by trypsin and the rhBDNF mature form is finally purified by two additional chromatographic steps If the wild-type precursor can be efficiently obtained by the proposed methodology, its pro-peptide remotion, through enzymatic digestion, is however problematic. To circumvent this difficulty, the precursor hinge region, containing the natural furin recognition site, was engineered to be more specifically cleaved by trypsin. Notwithstanding the substitution of three residues in the pro-region carboxyterminal, the precursor correctly refolds and is efficiently cleaved to generate a biologically active mature rhBDNF. This efficient high-yield process fills the current need of a scalable protocol to produce GMP-grade material and unlocks the rhBDNF employment in future clinical investigations.