FOOD SCIENCE ›› 2020, Vol. 41 ›› Issue (10): 124-130.doi: 10.7506/spkx1002-6630-20190305-049

• Bioengineering • Previous Articles     Next Articles

Effect of Co-expression of Chaperone PDI and Transcription Factor Aft1 on the Expression of Recombinant Human Lysozyme in Pichia pastoris

WANG Ruxin, HAN Qin, CHEN Yuanyuan, WU Jing, YAN Dazhong, LIU Jun, LI Xin   

  1. (College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China)
  • Online:2020-05-25 Published:2020-05-15

Abstract: This study attempted to improve the expression level of recombinant human lysozyme in Pichia pastoris by co-expression of the chaperone protein disulfide isomerase (PDI) and the transcriptional activator of ferrous transport-1 (Aft1) from P. pastoris. The constructed expression plasmids, pG418-PDI and pG418-Aft1, were linearized and integrated into the genome of P. pastoris KM71-HLY through homologous recombination by electroporation. The positive transformants were selected based on G418 resistance, yielding two recombinant strains, KM71-HLY-PG418-PDI and KM71-HLY-PG418-Aft1. Shake flask fermentation was performed to analyze the expression level of HLY in the engineered yeasts. Experimental results showed that KM71-HLY, KM71-HLY-pG418-PDI and KM71-HLY-pG418-Aft1 all produced human lysozyme (14.7 kDa) with inhibitory effects on Micrococcus lysodeik under the induction of methanol. These recombinant strains exhibited only a slight difference in the cell growth at the early stage of induction. However, the biomasses of KM71-HLY-PG418-PDI and KM71-HLY-PG418-Aft1 were lower than that of KM71-HLY after 70 h and their optical density values (OD600 nm) at the end of fermentation were 92.8% and 84.1% as compared to KM71-HLY, respectively. When induced by methanol for 168 h, the yields of total secretory protein of KM71-HLY, KM71-HLY-PG418-PDI and KM71-HLY-PG418-Aft1 were 324.02, 350.87 and 474.8 mg/L, and the lysozyme activities of the fermentation supernatants were 34 880, 45 600 and 50 180 U/mL, respectively. As compared to KM71-HLY, KM71-HLY-PG418-PDI and KM71-HLY-PG418-Aft1 increased total secretory protein production by 8.3% and 46.5%, and extracellular lysozyme activity by 30.7% and 43.9%, respectively.

Key words: human lysozyme, chaperone, transcriptional factor, co-expression, Pichia pastoris

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