title: Heat shock transcription factor 1 binds selectively in vitro to Ku protein and the catalytic subunit of the DNA-dependent protein kinase.
abstract: Heat shock transcription factor 1 (HSF1) functions as the master regulator of the heat shock response in eukaryotes. We have previously shown that, in addition to its role as a transcription factor, HSF1 stimulates the activity of the DNA-dependent protein kinase (DNA-PK). DNA-PK is composed of two components: a 460-kDa catalytic subunit and a 70- and 86-kDa heterodimeric regulatory component, also known as the Ku protein. We report here that HSF1 binds specifically to each of the two components of DNA-PK. Binding occurs in the absence of DNA. The complex with the Ku protein is stable and forms at a stoichiometry close to unity between the Ku protein heterodimer and the active HSF1 trimer. The binding is blocked by antibodies against HSF1. Our results show that HSF1 also binds directly, but more weakly, to the catalytic subunit of DNA-PK. Both interactions are dependent on a specific region within the HSF1 regulatory domain. This sequence is necessary but not sufficient for HSF1 stimulation of DNA-PK activity. The ability of HSF1 to interact with both components of DNA-PK provides a potential mechanism for the activation of DNA-PK in response to heat and other forms of stress.
authors.affiliation: Gene Regulation Program, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, Georgia 30912, USA.
authors.forename: J
authors.initials: J
authors.lastname: Huang
authors.forename: A
authors.initials: A
authors.lastname: Nueda
authors.forename: S
authors.initials: S
authors.lastname: Yoo
authors.forename: W S
authors.initials: WS
authors.lastname: Dynan
mesh_terms: D034961:Antigens, Nuclear; D002384:Catalysis; D004265:DNA Helicases; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D018604:Epitope Mapping; D006367:HeLa Cells; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000072200:Ku Autoantigen; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; C000619706:HSF1 protein, human; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen