Genetic evidence for separate functional domains on the human adenovirus specified, 72 kd, DNA binding protein

Seven mutations that affect various activities of the multifunctional DNA binding protein (DBP) encoded by human adenovirus have been physically mapped to different locations within DBP gene by marker rescue experiments. Two of these mutants (Ad5ts107 and Ad5ts125) contain a lesion which, under nonpermissive temperatures, decreases the capacity of the protein to bind single-strand DNA, blocks DNA replication, and prevents normal turn-off of viral early genes. In addition, the efficiency of transformation by the ts viruses compared to wild-type virus is increased at the nonpermissive temperature. Both ts mutations are located in the 3' half of the DBP gene (C-terminal half of DBP). In contrast, the alterations in the five host range mutants (Ad2hr400-Ad2hr403, Ad5hr404) which overcome the block to viral late mRNA synthesis in monkey cells, but have no marked effect on DNA replication or early gene expression map in the 5' half of the DBP gene. These results suggest that the 72 kd DBP of adenovirus contains at least two functionally separable domains.