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

Area of Science:

• Biotechnology
• Molecular Biology
• Protein Expression

Background:

• Periplasmic expression facilitates biologically active, correctly folded recombinant proteins.
• Recombinant human interleukin-15 (rhIL-15) has therapeutic potential but requires efficient production methods.

Purpose of the Study:

• To achieve efficient periplasmic expression and purification of functional rhIL-15 in E. coli.
• To evaluate different E. coli strains for optimal rhIL-15 expression.

Main Methods:

• In-frame cloning of rhIL-15 with a pelB-leader sequence into the pET-20 (+) vector.
• Expression trials in four E. coli strains: BL21 (DE3), BL21 (DE3) pLysS, Rosetta 2 (DE3), and Rosetta-gami 2 (DE3).
• Purification using dye ligand affinity chromatography and characterization via SDS-PAGE, Western blotting, and SEC-HPLC.

Main Results:

• Highest soluble periplasmic expression of rhIL-15 was observed in Rosetta-gami 2 (DE3) and Rosetta 2 (DE3) strains.
• Negligible expression was detected in BL21 (DE3) and BL21 (DE3) pLysS strains.
• Achieved a yield of 120 mg/L of purified functional rhIL-15.

Conclusions:

• Rosetta-gami 2 (DE3) is the optimal host for high-yield periplasmic expression of rhIL-15.
• This research presents the first report of functional rhIL-15 expressed and purified from the E. coli periplasm.