Secretory Expression of Human $\alpha_{s1}$-Casein in Saccharomyces cerevisiae

  • Kim, Yoo-Kyeong (Korea Research Institute of Bioscience and Biotechnology) ;
  • Yu, Dae-Yeul (Korea Research Institute of Bioscience and Biotechnology) ;
  • Kang, Hyun-Ah (Korea Research Institute of Bioscience and Biotechnology) ;
  • Yoon, Sun (Department of Food and Nutrition, Yonsei University) ;
  • Chung, Bong-Hyun (Korea Research Institute of Bioscience and Biotechnology)
  • Published : 1999.04.01

Abstract

A recombinant human $\alpha_{s1}$-casein was expressed as a secretory product in the yeast Saccharomyces cerevisiae. Three different leader sequences derived from the mating factor $\alpha$l (MF$\alpha$l), inulinase, and human $\alpha_{s1}$-casein were used to direct the secretion of human $\alpha_{s1}$-casein into the extracellular medium. Among the three leader sequences tested, the native leader sequence of human $\alpha_{s1}$-casein was found to be the most efficient in the secretory expression of human $\alpha_{s1}$-casein, which implies that the native leader sequence of human $\alpha_{s1}$-casein might be used very efficiently for the secretory production of other heterologous proteins in yeast. The recombinant human $\alpha_{s1}$-casein was proteolytically cleaved as the culture proceeded. Therefore, an attempt was made to produce human $\alpha_{s1}$-casein using a S. cerevisiae mutant in which the YAP3 gene encoding yeast aspartic protease 3 (YAP3) was disrupted. After 72 h of culture, most of the human $\alpha_{s1}$-casein secreted by the wild type was cleaved, whereas more than 70% of the human $\alpha_{s1}$-casein secreted by yap3-disruptant remained intact. The results suggest that YAP3 might be involved in the internal cleavage of human $\alpha_{s1}$-casein expressed in yeast

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