Primary structure of the Saccharomyces cerevisiae GAL7 gene.

We present the nucleotide sequence of a 1599-base pair (bp) DNA fragment containing the entire GAL7 gene that encodes galactose-1-phosphate uridyltransferase of Saccharomyces cerevisiae. The deduced peptide was composed of 364 amino acid residues. The expected molecular weight was 42,005 daltons, which agreed with the observed value for the purified enzyme. The 3'-end of the GAL7 transcript mapped at a position 82 bp downstream from the UAA termination codon by the S1 nuclease protection experiment. We constructed a GAL7'-lac'Z fusion on various types of yeast plasmid vectors. The fused gene on any type of vector was induced by galactose and repressed by glucose as for the GAL7 gene on the chromosome. The response of GAL7'-lac'Z fusion to gal4 delta and gal80 delta regulatory mutations was also similar to the response of the chromosomal GAL7 gene. By using various deletions in the 5'-flanking region of the gene fusion, we delimited the sequence essential for galactose controlled expression with a 180 bp-fragment of DNA lying 92 bp upstream of the transcription initiation site.