Abstract
At least 12 virus-induced DNA-binding proteins with mol. wt. ranging from 14 x 103 to 119 x 103 have been isolated from frog virus (FV 3)-infected fathead minnow cells by DNA affinity chromatography. Two enzymic activities, DNA-dependent DNA polymerase and endodeoxyribonuclease, were present in the DNA-binding proteins; these enzymic activities were similar to those induced by FV 3 in infected cells. A single species of DNA-binding protein with a mol. wt. of 36000 had very high affinity for single-stranded DNA, but a low one for double-stranded DNA. Proteins with such characteristic affinity for single-stranded DNA destabilize the DNA helix and are essential for viral DNA replication. Thus, the 36000 mol. wt. DNA-binding protein is a candidate for such a role in FV 3 DNA replication.