Expression of the major heat shock gene of Drosophila melanogaster in Saccharomyces cerevisiae.

A copy of the gene which encodes the major heat shock protein (hsp70) of D. melanogaster was integrated in both orientations into the genome of S. cerevisiae at the leu2 locus. The level of transcript from the D. melanogaster gene was measured under both normal conditions and conditions which are known to give rise to the heat shock response in S. cerevisiae. In both orientations the D. melanogaster gene gave rise to an abundant transcript in uninduced cells. The level of this transcript was increased transiently on heat shock, peaking after about 30 min at the elevated temperature. The average induction observed was around 5-fold. Although the D. melanogaster gene is heat inducible in S. cerevisiae, the transcripts are initiated at several sites which lie between 10 and 40 base pairs downstream of the initiation site in D. melanogaster. Thus, the transcriptional apparatus of S. cerevisiae appears to recognize the promoter and regulatory elements of the D. melanogaster major heat shock gene, although the manner in which transcription is initiated differs between the two species.