Epstein-Barr nuclear antigen 1 mediates a DNA loop within the latent replication origin of Epstein-Barr virus.
Epstein-Barr virus-encoded nuclear antigen 1 (EBNA-1) binds and activates the viral latent origin of DNA replication, oriP. We have used electron microscopy to examine the assembly of EBNA-1 onto oriP. The oriP region consists of two essential elements separated by approximately 1 kilobase pair of DNA. One element contains 20 tandom EBNA-1 binding sites [called the family of repeats (FR)] and serves to activate initiation of replication at the dyad symmetry (DS) element, which contains 4 EBNA-1 binding sites. Titration of homogeneous EBNA-1 produced in baculovirus (bEBNA-1) onto oriP DNA showed an order to the assembly of bEBNA-1 onto oriP. At low concentrations, bEBNA-1 was located exclusively on the FR element. As the level of bEBNA-1 was raised, a loop between the FR and DS elements became the most prevalent DNA-protein complex. These data suggest protein-mediated DNA looping may play a role in activating latent-phase replication of the Epstein-Barr virus.
Frappier
L
L
Howard Hughes Medical Institute, Microbiology Department, Cornell University Medical College, New York, NY 10021.
O'Donnell
M
M
D000956:Antigens, Viral / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D001665:Binding Sites; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics* / Q000648:ultrastructure; D019309:Epstein-Barr Virus Nuclear Antigens; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000378:metabolism / Q000648:ultrastructure; D015183:Restriction Mapping; D014779:Virus Replication
D000956:Antigens, Viral; D004279:DNA, Viral; D019309:Epstein-Barr Virus Nuclear Antigens; D011994:Recombinant Proteins