Cloning, Expression, and Purification of α, βa, and βb Subunits of Human Inhibin Protein in Escherichia coli

Background and Objectives: Inhibin is a glycoprotein hormone commonly found in the circulation, but its level increases in some diseases, and its measurement by serological method using anti-inhibin monoclonal antibodies, can help in diagnosis of some genetic diseases. This study was performed with the objective of cloning, expression, and purification of α, βa, and βb subunits of human inhibin protein in Escherichia coli.   Methods: For each Inhibin subunit gene. a primer pair was designed. Then, the gene sequence of each of the subunits, was obtained from human genomic DNA using polymerase chain reaction (PCR) method, and then was cloned into pET22b vector after enzymatic digestion. Recombinant vector associated with each subunit, was transferred to the host cell E. coli (strain BL21). The transformed cells were cultured in LB culture medium containing ampicillin, and positive colonies were isolated for mass production of recombinant protein. After mass culture and induction of transformed strains by isopropyl β-D-thiogalactopyranoside (IPTG), the produced recombinant protein, was isolated using nickel column chromatography.   Results: The inhibin hormone subunit genes, was correctly cloned in pET22b vector and its expression in E. coli, was considerably high. The results of the expression of inhibin hormone also showed that in the absence of codon optimization, the inhibin expression in the prokaryote host increases significantly. The protein subunits α, βa, and βb of inhibin hormone, were purified, respectively, with molecular weights of 13.7, 12, and 12 kDa.   Conclusion: protein subunits of inhibin hormone, can be expressed in the prokaryotic host due to their small size, short gene sequence, and minor post-transcriptional modifications.