A CCAAT box sequence in the adenovirus major late promoter functions as part of an RNA polymerase II termination signal.

Termination of transcription by RNA polymerase II has been shown in several cases to require a functional poly(A) addition site, although the actual termination event occurs further downstream. To define in more detail the sequences required for termination, we mapped the site at which transcription terminates on a chimeric plasmid template that contains the adenovirus MLP directing transcription of the SV40 early region. Termination in cells transfected with this plasmid occurs within a discrete promoter-proximal region that contains an inverted CCAAT-box sequence. This region of the MLP was also capable of directing termination, in an orientation-dependent manner, when inserted downstream of the poly(A) site in the plasmid template. In addition, in adenovirus-infected cells, transcription initiated from upstream promoters on the adenovirus chromosome terminates within the same MLP promoter-proximal region, both establishing the physiological relevance of the observed CCAAT-box dependent termination, and also suggesting a possible function for transcription termination in adenovirus infection.