Inhibition of adenovirus early region IV transcription in vitro by a purified viral DNA binding protein.

Adenoviruses depend on cellular mechanisms for the decoding of their genetic information, and so provide a useful and simple model system for the investigation of mammalian gene expression. The five regions transcribed early in adenovirus infection are termed EIa, EIb, EII, EIII and EIV. We report here that the primary product of the EII region, a 72,000 molecular weight DNA-binding protein (DBP), specifically represses transcription from the EIV promoter in an in vitro transcription system. Single-stranded DNA binds to the DBP with high affinity, and as a result inhibits its repressor activity. Our data extend previous genetic evidence that the DBP represses EIV transcription in vivo, and suggest that it acts directly by suppressing transcription from the EIV promoter.