Secretory expression of human alpha(s1)-casein in Saccharomyces cerevisiae

초록

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 1 (MF alpha 1), 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 a,,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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