Method for efficient soluble expression and purification of recombinant human Interleukin-15.

Ahmed, Nadeem; Afroze, Bakht; Abbas, Rabia; Khan, Mohsin Ahmed; Akram, Muhammad; Tahir, Saad; Bakht, Shehman; Munir, Ayesha; Shahid, Ahmad Ali

Periplasmic expression of recombinant proteins ensures the production of biologically active proteins in a correctly folded state with several key advantages. This research focused on the in-frame cloning of rhIL-15 in pET-20b (+) vector with pelB-leader sequence to direct the protein to the bacterial periplasm. The target construct periplasmic expression was evaluated in four strains, BL21 (DE3), BL21 (DE3) pLysS, Rosetta 2(DE3) and Rosetta-gami 2(DE3). Soluble periplasmic expression of IL-15 was highest in Rosetta-gami 2(DE3) followed by Rossetta 2(DE3) whereas negligible expression was observed with rest of two expression host. Best expression clone was selected for purification by dye ligand affinity chromatography. Purified rhIL-15 was characterized by SDS-PAGE, Western blotting and SEC-HPLC. This is the first report of functional recombinant human interleukin-15 being expressed and purified with yield of 120mg/L in the periplasmic space of E. coli.