Efficient accumulation of oleic acid in Saccharomyces cerevisiae caused by expression of rat elongase 2 gene (rELO2) and its contribution to tolerance to alcohols.

ABSTRACT

When the cells of Saccharomyces cerevisiae are exposed to high concentration of ethanol, the content of oleic acid (C181n-9) increased as the initial concentration of ethanol increased. Based on this observation, we attempted to confer ethanol tolerance to S. cerevisiae by manipulating fatty acid composition of the cells. Rather than altering OLE1 expression [the desaturase making both C161n-7 (palmitoleic acid) and C181n-9], we introduced elongase genes. Introduction of rat elongase 1 gene (rELO1) into S. cerevisiae gave cis-vaccenic acid (cis-C181n-7) by conversion from C161n-7, and the increase in this C181 fatty acid did not confer ethanol tolerance to the cells. On the other hand, the introduction of rat elongase 2 gene (rELO2), which elongates C160 to C180, drastically increased C181n-9 content, and the cells acquired ethanol tolerance, emphasizing the specific role of C181n-9. Furthermore, the transformant of rELO2 also conferred tolerance to n-butanol, n-propanol, and 2-propanol.