Interaction between transcription factors Spl and YY1

A BASAL level of transcription is usually observed when all but a small region of DNA has been deleted from a eukaryotic gene promoter. These promoter elements, which are necessary and sufficient for specific transcription initiation, are referred to as minimal or core promoter elements. One element that is commonly present in a core promoter is the initiator. It has been demonstrated that the presence of Spl binding sites can greatly enhance the level of transcription initiation at initiator elements^1-4. A binding site for the YY1 transcription factor, located at the initiation site of the adeno-associated virus P5 promoter, functions as an initiator element; a synergistic enhancement of its activity is observed in vitro when upstream Spl binding sites are present³. Here we report that this synergistic activation probably occurs through protein-protein interactions.