The C-terminal region of Drosophila heat shock factor (HSF) contains a constitutively functional transactivation domain.
The heat shock transcription factor (HSF) is constitutively expressed in Drosophila cells as an inactive monomer. Upon heat shock HSF undergoes trimerization and acquires high affinity DNA binding ability leading to specific interaction with its cognate elements in heat shock promoters. Here we show that the transactivation function of HSF is conferred by the extreme C-terminal region of the protein. Deletion analysis of HSF fragments fused to the GAL4 DNA-binding domain demonstrates that transactivation is dependent on HSF residues 610-691. This domain is located beyond the C-terminal heptad repeat (leucine zipper 4) whose presence or integrity is dispensable for transactivation. The transactivation domain is functional in the absence of heat shock and can be replaced by the extreme C-terminal region of human HSF1. The Drosophila and human HSF transactivation domains are both rich in hydrophobic and acidic residues and may be structurally conserved, despite limited sequence identity.
Wisniewski
J
J
Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Orosz
A
A
Allada
R
R
Wu
C
C
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D005656:Fungal Proteins / Q000235:genetics; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response; D006801:Humans; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics*
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; C000619706:HSF1 protein, human; D000076249:Heat Shock Transcription Factors; C053134:Hsf protein, Drosophila; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D004247:DNA