The adenovirus-inducible factor E2F stimulates transcription after specific DNA binding

The promoter-specific factor E2F interacts with critical regulatory sequences within the adenovirus E2 promoter. In addition, the level of active factor increases markedly during a virus infection, dependent on E1A function and coincident with the trans activation of E2 transcription. We have purified the E2F factor through a combination of standard biochemical procedures and DNA affinity chromatography. The purified factor was a single polypeptide of 54,000 molecular weight, as determined by UV crosslinking and renaturation of gel-fractionated protein. Addition of affinity-purified factor to an in vitro transcription system resulted in stimulation of transcription from a promoter containing two E2F-binding sites but not promoters lacking binding sites. We thus conclude that E2F is indeed capable of stimulating transcription once it has bound to the promoter.