Introductino of a Feed Back Resistant α-Isopropylmalate Synthase Gene of Saccharomyces cerevisiae into Sake Yeast

概要

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A mutant LEU4 gene (LEU4^<fbr>-2), responsible for both the overproduction of iso-amyl alcohol in yeast and the phenotype of yeast resistant to 5,5,5-trifluoro-DL-leucine (TEL), was isolated from a TFL-resistant mutant of Saccharomyces cerevisiae F-7. The single copy number of LEU4^<fbr>-2 complemented the leucine auxotrophy of S. cerevisiae HB190 (a, leu4,leu5), and also transformed it to TFL-resistant. Leucine-insensitive α-isopropylmalate synthase activity was detected in the crude extract of the Leu^+ transformant. Also sake yeast Kyokai no. 7 (K-7) was transformed by the LEU4^<fbr>-2 gene to TFL-resistant. THe resulting transformants produced 3〜30-fold higher levels of iso-amyl alcohol (approx. 50〜475 ppm) in shaking cultures, while in static cultures the increase in productivity was only 2.5-fold compared with that of recipient strain K-7. The isolated LEU4^<fbr>-2 gene may be useful as a positive selectable marker for the transformation of industrial yeast.
公益社団法人日本生物工学会の論文
1994-02-25