T-antigen is the only detectable protein on the nucleosome-free origin region of isolated simian virus 40 minichromosomes.
A nucleosome-free region or nucleosome gap, containing the origin of replication and the transcriptional promoter elements, is observed on 20%-25% of the SV40 minichromosomes isolated at physiological ionic strength at late time during the infectious cycle. We found that this subpopulation of gapped minichromosomes was more sensitive to digestion with a variety of single-cut restriction enzymes than the rest of the minichromosomes. This increased digestibility of gapped minichromosomes allowed us to excise the gap region by concomitant digestion with Bgl I and Msp I. T-antigen was the only detectable protein bound to this isolated chromatin fragment. In particular no histones could be detected. The presence of T-antigen on the gap region was confirmed by immunoelectron microscopy. Most of the T-antigen appeared to be located on the late side of the Bgl I restriction enzyme site.
D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor / Q000235:genetics*; D002460:Cell Line; D002522:Chlorocebus aethiops; D002875:Chromosomes / Q000648:ultrastructure; D004262:DNA Restriction Enzymes; D005796:Genes; D005814:Genes, Viral; D007668:Kidney; D008854:Microscopy, Electron; D009707:Nucleosomes / Q000648:ultrastructure; D009856:Oncogene Proteins, Viral / Q000235:genetics*; D011494:Protein Kinases / Q000235:genetics*; D013539:Simian virus 40 / Q000201:enzymology / Q000235:genetics*
D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor; D009707:Nucleosomes; D009856:Oncogene Proteins, Viral; D011494:Protein Kinases; D004262:DNA Restriction Enzymes