ISOLATION AND CHARACTERIZATION OF AAP1 - A GENE ENCODING AN ALANINE ARGININE AMINOPEPTIDASE IN YEAST

The yeast AAP1 gene, encoding a putative aminopeptidase, was isolated based on its ability to suppress the temperature-sensitive growth on n onfermentable carbon sources of spr5, a stationary phase regulatory mu tant. AAP1 was physically mapped to chromosome VIII between PUT2 and C UP1. Sequence analysis of the AAP1 gene showed a 1581-nucleotide open reading frame capable of encoding a 59-kilodalton protein. The protein encoded by this open reading frame exhibits approximately 40% sequenc e identity to human, rat, and mouse aminopeptidases. In limited region s, sequence identity between Aap1 and the mammalian aminopeptidases ra nges from 53% to 93%. Insertional inactivation of the AAP1 gene result ed in a decrease in glycogen accumulation and the loss of the major ba nd of arginine/alanine aminopeptidase activity. Strains carrying the A AP1 gene on a high copy plasmid show an increase in the major arginine /alanine aminopeptidase activity, a dramatic increase in glycogen accu mulation, and an increase in transcription from a vector carrying lacZ fused to the promoter of a gene (SSA3) expressed during post-diauxic and stationary phases of the culture cycle. We conclude that although the AAP1 gene is not essential for viability, the Aap1 protein positiv ely affects glycogen accumulation in yeast.