Occupancy of the Drosophila hsp70 promoter by a subset of basal transcription factors diminishes upon transcriptional activation.
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.
Lebedeva
Lyubov A
LA
Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de Recherche Scientifique, Unité Mixte de Recherche 7104, Université Louis Pasteur de Strasbourg, BP 10142, Illkirch, France.
Nabirochkina
Elena N
EN
Kurshakova
Mariya M
MM
Robert
Flavie
F
Krasnov
Aleksey N
AN
Evgen'ev
Mihail B
MB
Kadonaga
James T
JT
Georgieva
Sofia G
SG
Tora
Làszlò
L
D000818:Animals; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers; D004330:Drosophila / Q000235:genetics*; D019084:Fluorescent Antibody Technique, Indirect; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics* / Q000502:physiology
D017931:DNA Primers; D018840:HSP70 Heat-Shock Proteins; D014157:Transcription Factors