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Regulatory domain of human heat shock transcription Factor‐2 is not regulated by hemin or heat shock
Author(s) -
Zhu Zhen,
Mivechi Nahid F.
Publication year - 1999
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/(sici)1097-4644(19990401)73:1<56::aid-jcb7>3.0.co;2-7
Subject(s) - heat shock factor , leucine zipper , microbiology and biotechnology , transcription factor , dna binding domain , hemin , heat shock , atf3 , fusion protein , heat shock protein , hsf1 , chemistry , biology , activator (genetics) , bzip domain , biochemistry , hsp70 , gene , heme , promoter , gene expression , recombinant dna , enzyme
Heat shock transcription factor 2 (HSF‐2) activates transcription of heat shock proteins in response to hemin in the human erythroleukemia cell line, K562. To understand the regulation of HSF‐2 activation, a series of deletion mutants of HSF‐2 fused to the GAL‐4 DNA binding domain were generated. We have found that human HSF‐2 has a regulatory domain located in the carboxyl‐terminal portion of the protein which represses the activity of its activation domain under normal physiological conditions. The repressive effects of this domain can be eliminated by its deletion in GAL4‐HSF‐2 fusion constructs. The regulatory domain of HSF‐2 can also repress a heterologous chimeric activator that contains a portion of the VP16 activation domain. The activation domain of HSF‐2 is a segment of approximately 77 amino acids located proximal to the carboxyl‐terminal hydrophobic heptad repeat (leucine zipper 4) of the molecule. Interestingly, the GAL4‐HSF‐2 fusion protein and the 77 amino acids activation domain are inactive and are not activated by pretreatment of cells with either hemin or elevated temperature. Our data suggest that regulation of HSF‐2 differs from HSF‐1 in that its regulatory domain is not responsive to hemin or heat directly. J. Cell. Biochem. 73:56–69, 1999. © 1999 Wiley‐Liss, Inc.