Isolation of a mutant allele that deregulates the threonine biosynthesis in Saccharomyces cerevisiae

Martin-Rendon, E. . Facultad de Biologia. Dept. de Genetica; Farfan, M.J.; Ramos, C.; Calderon, I.L.

Isolation of a mutant allele that deregulates the threonine biosynthesis in Saccharomyces cerevisiae

1993

Martin-Rendon, E. (Sevilla Univ. (Spain). Facultad de Biologia. Dept. de Genetica) | Farfan, M.J. | Ramos, C. | Calderon, I.L.

The yeast allele HOM3-R2 was cloned, that codes for a mutant aspartate kinase which is insensitive to feedback inhibition by threonine, by gap-repair. A strain carrying this allele in a multicopy plasmid, or integrated into the genome, accumulates 14-times and 8-times more threonine than the wild-type, respectively. The sequence of the mutant allele differs from that of the wild-type in a single base pair change, namely a G by an A, at position 1355 in the open reading frame. The fact that the presence of this mutant allele in a cell induces threonine overproduction points to aspartate kinase as the key enzyme in the regulation of threonine biosynthesis in yeast.

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