Expression and characterization of the antimicrobial peptide ABP-dHC-cecropin A in the methylotrophic yeast Pichia pastoris

•This is the first report of the use of Pichia pastoris for expression and purification of ABP-dHC-Cecropin A.•The optimal conditions were 20 °C, 2% casamino acids, 0.5% methanol, which induced expression for 96 h.•Approximately 48 mg of recombinant protein was secreted into 1L of medium.•The antibacterial and antifungal activities of recombinant protein are similar to those of the synthetic protein.•This method provides benefits of simple operation, high yield of the recombinant protein, and good activity.

ABP-dHC-cecropin A is a linear cationic peptide that exhibits antimicrobial properties. To explore a new approach for expression of ABP-dHC-cecropin A using the methylotrophic yeast Pichia pastoris, we cloned the ABP-dHC-cecropin A gene into the vector pPICZαA. The SacI-linearized plasmid pPICZαA-ABP-dHC-cecropin A was then transformed into P. pastoris GS115 by electroporation. Expression was induced after a 96-h incubation with 0.5% methanol at 20 °C in a culture supplied with 2% casamino acids to avoid proteolysis. Under these conditions, approximately 48 mg of ABP-dHC-cecropin A was secreted into 1L (4 × 250-mL)of medium. Recombinant ABP-dHC-cecropin A was purified using size-exclusion chromatography, and 21 mg of pure active ABP-dHC-cecropin A was obtained from 1L (4 × 250-mL)of culture. Electrophoresis on 4-20% gradient gels indicated that recombinant ABP-dHC-cecropin A was secreted as a protein approximately 4 kDa in size. Recombinant ABP-dHC-cecropin A was successfully expressed, as the product displayed antibacterial and antifungal activities (based on an antibacterial assay, scanning electron microscopy, and antifungal assay) indistinguishable from those of the synthesized protein.