Designing a Thermostable Mini-Intein for Intein-Mediated Purification of Recombinant Proteins and Peptides

This paper reports design of a thermostable temperature-activated mini-intein based on the full-length intein DnaE1 from Thermus thermophilus HB27 (TthDnaE1). We performed rational design of three mini-inteins TthDnaE1 Δ272, Δ280 and Δ287 through deletion mutations in the full-length intein sequence. Two mini-inteins (Δ272 and Δ280) were capable of efficient protein splicing at temperatures above 50°C. The most active mini-intein with the Δ280 deletion was chosen as the basis for further design of a self-cleaving carrier of affinity tags through single-point mutagenesis. We performed the C1A, D405G and C1A/D405G mutations, which were proposed to eliminate the intein’s capability of N-terminal extein cleavage and extein ligation. As a result, the mini-intein Δ280 with double mutation C1A/D405G displayed the highest efficiency of C-terminal extein cleavage at its temperature optimum around 60°C. Thus, we constructed thermostable temperature-activated mini-inteins capable of efficient protein splicing or cleavage of C-terminal extein. The engineered TthDnaE1 Δ280 C1A/D405G mini-intein can serve as basis for the development of new expression system for intein-mediated production of pharmaceutical recombinant proteins and peptides.