Combinatorial Control of Transcription: The Herpes Simplex Virus VP16-induced Complex

Abstract

Common features of transcriptional regulation in multicellular organisms are the modular and combinatorial structure of cis-acting DNA sequences and trans-acting proteins. Promoters represent the cis-acting regulatory elements and consist of proximal and basal elements positioned near the transcriptional initiation site and enhancers, which can be located far from the transcriptional initiation site. These elements, especially enhancers, are in turn each composed of multiple modules or transcription factor binding sites that are arranged in combinations that specify a given pattern of transcriptional regulation. Transcription factors are also modular, frequently consisting of transcriptional activation domains, which interact with other proteins in the transcriptional machinery, and DNA-binding domains, which tether the activation domain to the appropriate promoter. The modularity of transcription factors is flexible; activation and DNA-binding modules can be exchanged between transcription factors, thereby creating chimeric molecules with new regulatory properties (Brent and Ptashne 1985).