Binding of a simian virus 40 T antigen-related protein to DNA

Abstract

The interaction between the simian virus 40 (SV40) T antigen-related protein D2T (Hassel et al., 1978) and DNA was investigated using monoclonal antibodies raised against D2T. DNA bound by D2T was separated from free DNA by a simple modification of the Staphylococcus aureus immunoprecipitation procedure. Three forms of D2T could be detected in extracts of cells infected with the adeno-SV40 hybrid virus Ad2D2. One form did not bind DNA, the second bound to any DNA non-specifically, and the third bound tightly to the region of SV40 DNA spanning the origin of replication. The half-life of the specific complex was approximately 100 minutes at 25 °C but the non-specific binding was very unstable ( ). Mutants of SV40 that lack the second and third binding sites show undiminished ability to bind D2T specifically; but mutant DNAs that lack the first and second binding sites interact poorly with D2T. Finally, another region of the SV40 genome showed preferential binding to D2T. However, the decay rate of this site in the EcoRII/D fragment was rapid and, under these conditions, could not be distinguished from non-specific binding.