title: The simian-virus-40 large-tumor antigen in replicating viral chromatin. A salt-resistant protein-DNA interaction.
abstract: The large tumor antigen (T antigen) is a genome regulation protein, coded by simian virus 40, 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. In fact, a considerable fraction of T antigen remains associated with replicating chromatin at NaCl concentrations 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. We consider the possibility that the unexpectedly tight binding of T antigen to replicating DNA is related to the function that T antigen performs during viral DNA replication.
mesh_terms: D000951:Antigens, Neoplasm / Q000302:isolation & purification*; D000956:Antigens, Viral / Q000302:isolation & purification*; D000957:Antigens, Viral, Tumor; D001665:Binding Sites; D002843:Chromatin / Q000378:metabolism*; D004261:DNA Replication; D004279:DNA, Viral / Q000378:metabolism*; D004351:Drug Resistance; D007120:Immunochemistry; D013539:Simian virus 40 / Q000276:immunology*; D012965:Sodium Chloride; D014779:Virus Replication
chemical_list: D000951:Antigens, Neoplasm; D000956:Antigens, Viral; D000957:Antigens, Viral, Tumor; D002843:Chromatin; D004279:DNA, Viral; D012965:Sodium Chloride