High expression of a plectasin-derived peptide NZ2114 in Pichia pastoris and its pharmacodynamics, postantibiotic and synergy against Staphylococcus aureus

NZ2114, a new variant of plectasin, was overexpressed in Pichia pastoris X-33 via pPICZαA for the first time. The total secreted protein of fermentation supernatant reached 2,390 mg/l (29 °C) and 2,310 mg/l (25 °C), and the recombinant NZ2114 (rNZ2114) reached 860 mg/l (29 °C) and 1,309 mg/l (25 °C) at 96 h induction in a 5-l fermentor, respectively.The rNZ2114 was purified by cation exchange chromatography, and its yield was 583 mg/l with 94.8 % purity. The minimal inhibitory concentration (MIC) of rNZ2114 to four ATCC strains of Staphyloccocus aureus was evaluated from 0.028 to 0.90 μM. Meanwhile, it showed potent activity (0.11–0.90 μM) to 20 clinical isolates of MRSA. The rNZ2114 killed over 99.9 % of tested S. aureus (ATCC 25923 and ATCC 43300) in Mueller-Hinton medium within 6 h when treated with 4?×?MIC. The postantibiotic effect of rNZ2114 to S. aureus ATCC 25923 and ATCC 43300 was 18.6–45.6 and 1.7–3.5 h under 1×, 2×, and 4× MIC, respectively. The fractional inhibitory concentration index (FICI) indicated a synergistic effect between rNZ2114 and kanamycin, streptomycin, and vancomycin against S. aureus ATCC 25923 (FICI?=?0.125), and additivity between rNZ2114 and ampicillin, spectinomycin (FICI?=?0.625), respectively. To S. aureus ATCC 43300 methicillin-resistant S. aureus (MRSA)], rNZ2114 showed a synergistic effect (FICI?=?0.125–0.3125) with kanamycin, ampicillin, streptomycin, and vancomycin, and antagonism with spectinomycin (FICI?=?8.0625). The rNZ2114 caused only less than 0.1 % hemolytic activity in the concentration of 128 μg/ml, and showed a good thermostability from 20 to 80 °C. In addition, it exhibited the highest activity at pH 8.0. These results suggested that large-scale production of NZ2114 is feasible using the P. pastoris expression system, and it could be a new potential antimicrobial agent for the prevention and treatment of S. aureus especially for MRSA infections.