Natural and synthetic heat shock protein gene promoters assayed in Drosophila cells

Hybrid genes containing mRNA encoding sequences for herpes virus thymidine kinase (tk), chloramphenicol acetyltransferase (CAT), or Drosophila alcohol dehydrogenase (Adh), ligated to truncated Drosophila melanogaster heat-shock protein 70 (hsp 70) gene promoters or to synthetic sequences containing one or several copies of a previously defined heat-shock consensus sequence, were transfected into cultured Drosophila line S3 cells. Each construction was then assayed for gene expression at 25 degrees C and 37 degrees C, using a CAT enzyme assay, slot blot hybridization, or S1 nuclease protection analysis. In the Drosophila cell transient expression assay system, we found that deletions extending beyond position -97, or synthetic constructions containing a single heat shock consensus sequence, were not induced by high-temperature shock. In constructions containing deletions extending to position -186, -130, or -97, in the hsp 70 promoter, and in synthetic constructions containing tandemly spaced heat-shock consensus sequences mRNA transcription was greatly induced by high temperature.