Turning Genes On and Off
Science Magazine V. 290, N. 5493 3nov00
Regulating the production (or transcription) of RNA from a gene is the main control point for many cellular processes. This regulation is affected through a gene's promoter, a short sequence of DNA that has binding sites for a number of protein factors. The core promoter is sufficient to define the start sight of the RNA made from a gene. Elements of the core promoter of protein-coding genes include the TATA box, the initiator, and the recently discovered downstream promoter element (DPE). Willy et al. (p. 982 BELOW) have isolated a factor required for the activation of transcription from promoters containing DPEs. Surprisingly, the factor turns out to have been previously characterized as a general repressor of transcription, NC2, an observation explained by its ability to repress TATA-box-containing promoters. The activation and repression functions of NC2 are separable.
A Basal Transcription Factor That Activates or Represses Transcription
We have identified an activity that is required for transcription of downstream promoter element (DPE)-containing core promoters in vitro. The purified factor was found to be the Drosophila homolog of the transcriptional repressor known as NC2 or Dr1-Drap1. Purified recombinant dNC2 activates DPE-driven promoters and represses TATA-driven promoters. A mutant version of dNC2 can activate DPE promoters but is unable to repress TATA promoters. Thus, the activation and repression functions are distinct. These studies reveal that NC2 (Dr1-Drap1) is a bifunctional basal transcription factor that differentially regulates gene transcription through DPE or TATA box motifs.
1 Section of Molecular Biology and Center for Molecular Genetics,
University of California, San Diego, La Jolla, CA 92093-0347, USA.
2 Cold Spring Harbor Laboratory, Post Office Box 100, Cold
Spring Harbor, NY 11724, USA.
* To whom correspondence should be
addressed. E-mail: jkadonaga@ucsd.edu
