Mutational mapping of a cloned adenovirus origin.

We have developed a standardized, quantitative assay to study the function of a cloned adenovirus origin. We have shown that the adenovirus origin is located within the first 20 bp of the adenovirus inverted terminal repetition (ITR), a region containing a sequence conserved among human, simian, murine, and avian adenoviruses. Deletions removing or penetrating from either direction into the conserved sequence inactivated the cloned adenovirus origin. A point mutation within the conserved sequence impaired the adenovirus origin, but point mutations outside the conserved sequence had no effect. These results strongly suggest that the conserved sequence within the first 20 bp of the ITR alone constitutes the adenovirus origin (ori) signal.