Mediator, not holoenzyme, is directly recruited to the heat shock promoter by HSF upon heat shock.
Activators of RNA polymerase II (Pol II) transcription have been shown to bind several coactivators and basal factors in vitro. Whether such interactions play a primary regulatory role in recruiting these factors to activator-associated chromosomal target sites in living cells remains unclear. Here, we show that upon heat shock the Pol II-free form of Mediator is rapidly recruited to HSF binding sites. Unlike the TAFs and Pol II, the interaction between Mediator and HSF on chromosomal loci is direct and mechanistically separable from the preinitiation complex assembly step. Therefore, the activator-Mediator interaction likely underlies the initiation of signal transfer from enhancer-bound activators to the basal transcription machinery.
Park
J M
JM
National Creative Research Initiative Center for Genome Regulation, Department of Biochemistry, Yonsei University, 120-749, Seoul, South Korea.
Werner
J
J
Kim
J M
JM
Lis
J T
JT
Kim
Y J
YJ
D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D030801:Animals, Genetically Modified; D001665:Binding Sites; D002478:Cells, Cultured; D002875:Chromosomes; D004268:DNA-Binding Proteins / Q000378:metabolism*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D017344:Genes, Insect; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response; D046911:Macromolecular Substances; D009687:Nuclear Proteins / Q000378:metabolism*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012319:RNA Polymerase II / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012469:Salivary Glands / Q000502:physiology; D013997:Time Factors; D014157:Transcription Factors; D015533:Transcriptional Activation
D000546:Amanitins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C053134:Hsf protein, Drosophila; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D011994:Recombinant Proteins; D014157:Transcription Factors; D012319:RNA Polymerase II