Evidence for the control of a mutation in lysine catabolism by the mating type in Yarrowia lipolytica.

Reversions of a mutation lye 1.5 blocking the first step of the lysine catabolic pathway were isolated. These reversions mapped inside the LYC1 locus. They exhibited an alteration of the regulation of the lysine pool after nitrogen and phosphorus starvation. This phenomenon did not appear in sexual diploids homozygous for the reversion. Diploids homozygous for the mating type were constructed by protoplast fusion. They displayed a pattern similar to that of the haploids. We conclude that the expression of this mutation is under the control of the physiological state of the mating type.