Intein Based Fusion Proteins: Great Tags for the Soluble Production and Convenient Purification of Recombinant Proteins

Abstract

Background: The main problem in the recombinant protein expression in E. coli strains, especially for high-yield production, is the accumulation in un-folded and inactive inclusion bodies. A suitable solution is the direction into the soluble cytoplasmic products by solubilizing tags. The use of inteins with self-cleaving ability, in addition to increase the chance of soluble protein expression, facilitates their purification process.

Evidence acquisition: In this review article, papers related to the use of intein tags for soluble expression or protein purification were collected regardless the time limit. Available databases including Pubmed, google scholar, ScienceDirect, Web of Science, Scopus, and Embase was searched. The best condition for soluble expression or purification was focused in all articles.

Results: There are various intein tags commercially available in expression vectors that results in gaining our goal in facilitating the recombinant protein solubilization as well as its simple purification. It is enough to induce the self-cleavage property of the intein, which varies according to the type of intein used. In this way, the target protein is easily separated from the purification tag without the need to add protease enzymes such as enterokinase or treatment with various chemicals. The most common affinity tag in intein-based systems is Chitin Binding Domain attached to the chitin resin.

Conclusions: In this review article, we introduced proteins or peptides which produced in fusion to intein tags and discussed about their expression condition and purification process in order to enhance the chance of soluble expression and intein cleavage in a single stage, respectively.

Keywords: Chitin Binding Domain; Intein; Purification; Soluble Expression.

Figure 1

Schema of thiol-induced and pH-induced cleavage of two various inteins using the chitin column. A) C-terminal fusion of the target protein to the inteins that auto-cleaved by the addition of a reducing agent. B) N-terminal fusion of the target protein to the inteins that auto-cleaved by a shift in the buffer pH. C) C- and N-terminal fusion of the target protein to the inteins that auto-cleaved by the addition of a reducing agent and a shift in the buffer pH, respectively. TP: target protein, T-i: thiol-induced cleavage, pH-i: pH- induced cleavage, IN: intein, and CBD: Chitin Binding Domain.