Expression of integrated viral DNA sequences outside the transforming region in eight adenovirus-transformed cell lines

Physicochemical properties of the DNAs of the fastidious adenovirus species 40 and 41

The DNAs of the two fastidious adenovirus species 40 and 41 (Ad40 and Ad41) have been studied by restriction endonuclease cleavage, CsCl density gradient centrifugation, and liquid-phase hybridization. For Ad40 DNA, cleavage maps were constructed for the restriction endonucleases EcoRI, SalI, ClaI, BstEII, BclII, and PvuI. The EcoRI, SalI, ClaI, and XhoI maps could be established for Ad41 DNA. The buoyant density in CsCl of DNAs of the fastidious species is 1.711 g/cm3 corresponding to a G + C content of 52%. The homology of the DNAs from Ad40 and Ad41 proved to be 62-69%. These results are consistent with previous reports on antigenic and DNA restriction enzyme analysis in which the classification into two species was proposed (J. C. De Jong, R. Wigand, A. H. Kidd, G. Wadell, J. G. Kapsenberg, C. J. Muzerie, A. G. Wermenbol, and R.-G. Fritzlaff, J. Med. Virol. 11, 215-231 (1983), and I. Uhnoo, G. Wadell, L. Svensson, and M. Johansson, Dev. Biol. Stand. 53, 311-318 (1983].

Specific binding of the adenovirus terminal protein precursor-DNA polymerase complex to the origin of DNA replication

Initiation of adenovirus DNA replication is dependent on a complex of the precursor of the terminal protein and the adenovirus-coded DNA polymerase (pTP-pol complex). This complex catalyzes the formation of a covalent linkage between dCMP and pTP in the presence of a functional origin of DNA replication residing in the terminal nucleotide sequence of adenovirus DNA. We have purified the pTP-pol complex of adenovirus type 5 and studied its binding to double-stranded DNA. Using DNA-cellulose chromatography it could be shown that the pTP-pol complex has a higher affinity for adenovirus DNA than for calf thymus or pBR322 DNA. From the differential binding of the pTP-pol complex to plasmids containing adenovirus terminal sequences with different deletions, it has been concluded that a sequence of 14 nucleotide pairs at positions 9-22 plays a crucial role in the binding of pTP-pol to adenovirus DNA. This region is conserved in the DNA's of all human adenovirus serotypes and is obviously an important structural element of the adenovirus origin of DNA replication. Comparative binding studies with adenovirus DNA polymerase and pTP-pol indicated that pTP is responsible for the binding. The nature of the binding of pTP-pol to the conserved sequence will be discussed.

Immunological characterization of the role of adenovirus terminal protein in viral DNA replication

The function of the adenovirus-coded terminal protein and its precursor in viral DNA replication was studied by raising an antiserum against the adenovirus type 5 (Ad5) terminal protein isolated from virions. This antiserum reacted with both the terminal protein and its precursor as measured by a radioimmunoassay. In an in vitro DNA replication system employing nuclear extracts the addition of antiserum inhibits replication when a DNA-terminal protein complex from adenovirions is used as template. The replication of a 3.8% terminal fragment of the Ad2 genome with a protein-free origin (derived from the plasmid XD-7) is also inhibited by the antiserum. This observation confirms a role of the terminal protein precursor in DNA replication. The antiserum completely inhibited the formation of a covalent complex between the precursor terminal protein and dCMP, which is essential for initiation. A function of the terminal protein in the elongation reaction was shown by the inhibitory effect of antiserum on DNA chain elongation in isolated nuclei from Ad5-infected cells. Also in the in vitro DNA replication system employing nuclear extracts the elongation reaction is strongly reduced by addition of the antiserum. These results indicate that the terminal protein and/or its precursor are not only involved in initiation of DNA replication but also in DNA chain elongation.