Identification of a transcription factor which interacts with the distal domain of the adenovirus IVa2 promoter.

For efficient in vitro transcription from the adenovirus IVa2 promoter, two upstream control regions, one proximal to the RNA initiation site at nucleotide position (np) -39 to -48 and the other a distal domain between np -152 and -179, are necessary. By using the band competition assay of Strauss and Varshavsky (Cell 37:889, 1984), we identified a factor which binds to the IVa2 promoter. Competition studies with various deletion mutants demonstrated that the region present 152 to 160 base pairs upstream of the IVa2 transcription start site was necessary for binding of this factor. DNase I footprinting assays demonstrated directly that this factor interacted with the distal domain of the IVa2 promoter. This factor was necessary for efficient transcription from the IVa2 promoter, as evidenced by the ability of a DNA fragment containing the binding site for this factor to inhibit transcription. Its role in bidirectional activation of transcription from major late and IVa2 promoters is discussed.