Replication-dependent activation of the adenovirus major late promoter is mediated by the increased binding of a transcription factor to sequences in the first intron.

Abstract During lytic infection, the adenovirus major late promoter (MLP) is primarily activated after the onset of viral DNA replication. Using a combination of DNA binding and in vitro transcription assays, we delineated a discrete MLP element spanning positions +80 to +106 which is essential for the replication-dependent activation of this promoter. We also identified a 40- kilodaltonprotein (the downstream element factor [DEF]) which binds to the +86-TTGTCAGTTT-+95 motif within this element. Whereas the DEF-binding activity is barely detectable in uninfected cells, it is readily visualized in adenovirus-infectedcells, but only after the onset of viral DNA replication. Preventing the interaction of DEF with the MLP template impairs the in vitro transcriptional stimulation. We conclude that this replication-dependent activation of the MLP is, at least in part, mediated by induction of the specific binding of DEF to the MLP downstream element.