Expression of a cDNA encoding human 5-lipoxygenase under control of the STA1 promoter in Saccharomyces cerevisiae

A yeast-expression vector utilizing the STA1 promoter was constructed, and shown to be useful for the expression of a heterologous gene. A cDNA, encoding human 5-lipoxygenase (5LO), was inserted into the vector and expressed in Saccharomyces cerevisiae. The enzyme (yh5LO) produced in the transformant was purified to homogeneity from the cellular soluble fraction. The purified enzyme showed both 5LO and leukotriene A4 synthase activities, which were stimulated by Ca2+ and ATP. The N-terminal end of yh5LO contained five extra amino acids not present in 5LO purified from human leukocytes. A human 5LO-secretion vector containing the STA1 signal sequence was also constructed. When this hybrid gene was expressed in S. cerevisiae, its product was glycosylated and accumulated in the fractions related to the secretory pathway.