In Drosophila cell, an RNA polymerase is present on the 5' end of the uninduced hsp70 gene and is transcriptionaly engaged, but paused. The polymerase has ready access to this uninduced gene and can initiate transcription, but is impeded from progressing beyond early elongation. To analyze the biological role of the paused polymerase, we developed the model system. The results showed the possibility of the function of paused polymerase for quick activation of the gene. GAGA factor, a general transcription factor found to interact with GA CT repeats present in Drosophila is capable of binding to heat shock promoter sequences under non heat shock condition.
GAGA factor is directly responsible for the displacement of histones from the heat shock promoter.
In addition to the replacement of chromatin structure, we found the direct function as a transcription acrivator on the GAGA factor. We focus on the detail analyses of the function of GAGA factor and mechanism of paused polymerase.