TRANSCRIPTIONAL REPRESSION BY YY1, A HUMAN GLI-KRUPPEL-RELATED PROTEIN, AND RELIEF OF REPRESSION BY ADENOVIRUS E1A PROTEIN

A sequence within the transcription control region of the adeno-associated virus P5 promoter has been shown to mediate transcriptional activation by the adenovirus E1A protein. We report here that this same element mediates transcriptional repression in the absence of E1A. Two cellular proteins have been found to bind to overlapping regions within this sequence element. One of these proteins, YY1, is responsible for the repression. E1A relieves repression exerted by YY1 and further activates transcription through its binding site. A YY1-specific cDNA has been isolated. Its sequence reveals YY1 to be a zinc finger protein that belongs to the GLI-Kruppel gene family. The product of the cDNA binds to YY1 sites. When fused to the GAL4 DNA-binding domain, it is capable of repressing transcription directed by a promoter that contains GAL4-binding sites, and E1A proteins can relieve the repression and activate transcription through the fusion protein.