Occupancy of the Drosophila hsp70 promoter by a subset of basal transcription factors diminishes upon transcriptional activation

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 102; no. 50; pp. 18087 - 18092
• Main Authors: Lebedeva, L.A, Nabirochkina, E.N, Kurshakova, M.M, Robert, F, Krasnov, A.N, Evgen'ev, M.B, Kadonaga, J.T, Georgieva, S.G, Tora, L
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 13.12.2005; National Acad Sciences
• Subjects: Animals; Antibodies; binding capacity; Binding sites; Biochemistry, Molecular Biology; Biological Sciences; Chromatin; Chromatin Immunoprecipitation; DNA Primers; Drosophila; Drosophila - genetics; Drosophila melanogaster; Fluorescent Antibody Technique, Indirect; general transcription initiation factor; Genes; Genetic loci; Genetics; heat shock proteins; heat stress; HSP70 Heat-Shock Proteins; HSP70 Heat-Shock Proteins - genetics; hsp70 promoter; Life Sciences; Molecular biology; Polymerase Chain Reaction; Polytene chromosomes; Promoter regions; Promoter Regions (Genetics); Promoter Regions, Genetic - genetics; Proteins; Shock heating; Shock tests; TATA-binding protein; TATA-binding protein-associated factors; Trans-Activation (Genetics); transcription (genetics); Transcription Factors; Transcription Factors - genetics; Transcription Factors - metabolism; Transcriptional activation; Transcriptional Activation - genetics; Transcriptional Activation - physiology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0509063102

The presence of general transcription factors and other coactivators at the Drosophila hsp70 gene promoter in vivo has been examined by polytene chromosome immunofluorescence and chromatin immunoprecipitation at endogenous heat-shock loci or at a hsp70 promoter-containing transgene. These studies indicate that the hsp70 promoter is already occupied by TATA-binding protein (TBP) and several TBP-associated factors (TAFs), TFIIB, TFIIF (RAP30), TFIIH (XPB), TBP-free/TAF-containg complex (GCN5 and TRRAP), and the Mediator complex subunit 13 before heat shock. After heat shock, there is a significant recruitment of the heat-shock transcription factor, RNA polymerase II, XPD, GCN5, TRRAP, or Mediator complex 13 to the hsp70 promoter. Surprisingly, upon heat shock, there is a marked diminution in the occupancy of TBP, six different TAFs, TFIIB, and TFIIF, whereas there is no change in the occupancy of these factors at ecdysone-induced loci under the same conditions. Hence, these findings reveal a distinct mechanism of transcriptional induction at the hsp70 promoters, and further indicate that the apparent promoter occupancy of the general transcriptional factors does not necessarily reflect the transcriptional state of a gene.