In the yeast Yarrowia lipolytica, the LYC1 locus controls the first step of the lysine degradation pathway which is catalyzed by lysine N-6-acetyl transferase (LAT). This gene was cloned by complementation of the lyc1-100 mutation. Its position in the cloned insert was determined by conversion mapping and by complementation. The LYC1 gene encodes a 391 amino-acid polypeptide which has no homolog in protein databases. The required upstream region extends over 960 bp. When placed under the control of the GAL10 promoter in Saccharomyces cerevisiae, LYC1 drives the expression of lysine acetyl transferase activity, thus providing strong evidence that it is the structural gene encoding this enzyme.