DIFFERENTIAL REGULATION OF THE 70K HEAT-SHOCK GENE AND RELATED GENES IN SACCHAROMYCES-CEREVISIAE

S. cerevisiae contains a family of genes related to Hsp70, the major heat shock gene of Drosophila melanogaster. The transcription of 3 of these genes, which show no conservation of sequences 5'' to the protein-coding region, was analyzed. The 5'' flanking regions from the 3 genes were fused to the Escherichia coli .beta.-galactosidase structural gene and introduced into yeasts on multicopy plasmids, putting the .beta.-galactosidase production under yeast promoter control. Analysis of .beta.-galactosidase mRNA and protein production in these transformed strains revealed that transcription from the 3 promoters is differentially regulated. The number of transcripts from 1 promoter is vastly increased for a brief period after heat shock, whereas mRNA from another declines. Transcripts from a 3rd gene are slightly enhanced on heat shock; however, multiple 5'' ends of the mRNA are found, and a minor species increases in amount after heat shock. Transcription of these promoters in their native state on the chromosome appears to be modulated in the same manner.