Effect of Temperature, Inducer Concentration, and Escherichia coli Cytosolic Redox State on MBP-PI2 Expression

Type II proteinase inhibitors (PI2) found in potato (Solanum tuberosum) have been observed to confer protective enzymatic activity towards foreign proteases and were shown to have potential in applied contexts including anticancer and hunger suppression. Previous studies in our laboratory have synthesised, cloned, expressed and purified a PI2 variant fused to maltose binding protein, termed MBP-PI2. We studied MBP-PI2 expression levels with respect to growth temperature (30°C vs 37°C), isopropyl β-D-1-thiogalactopyranoside (IPTG) inducer concentration, and cytosolic redox state using Escherichia coli strains Origami 2 (DE3) and BL21 (DE3) SDS-PAGE analysis of whole cell lysate show that the highest level of MBP-PI2 expression occurred in strain BL21 (DE3) with a 2 hour induction period. Expression was not detected in strain Origami 2 (DE3). Similar expression levels of MBP-PI2 were observed at 30°C vs 37°C and 0.2 mM vs 1 mM IPTG. Our study acts as a framework for future experiments exploring the production and application of MBP-PI2.