The Simian‐Virus‐40 Large‐Tumor Antigen in Replicating Viral Chromatin

Publisher Website
Google Scholar
Abstract
The large tumor antigen (T antigen) is a genome regulation protein, coded by SV40, that binds with high affinity to specific binding sites on viral DNA. The specifically bound T antigen is released from these sites in 0.2-0.3 M NaCl. Immunoprecipitation techniques were used to show that T antigen also dissociates in 0.2-0.3 M NaCl from mature viral chromatin but not from replicating viral chromatin. A considerable fraction of T antigen remains associated with replicating chromatin at NaCl concentration as high as 1.2 M NaCl when most chromatin proteins, including histones, dissociate. However, T antigen binding to both replicating DNA and mature DNA is sensitive to intercalating drugs such as caffeine and ethidium bromide. The unexpectedly tight binding of T antigen to replicating DNA may be related to the function that T antigen performs during viral DNA replication.