title: Origin of DNA replication in papovavirus chromatin is recognized by endogenous endonuclease.
abstract: Isolated simian virus 40 (SV40) and polyoma nucleoprotein complexes contain endonuclease that, under in vitro conditions, converts part (up to 30%) of the covalently closed superhelical DNA to full-length linear rods. The positions of the cleavage sites within the genomes of SV40 and polyoma were determined by digestion with various single-cut restriction endonucleases and subsequent agarose gel electrophoresis of the cleavage products. Both SV40 and polyoma covalently closed superhelical DNA were cleaved open at their respective origins of DNA replication (+/- 75 base pairs). The full-length linear DNA rods whose ends map adjacent to the origin of DNA replication could also be isolated by sodium dodecyl sulfate/phenol extraction both from SV40-infected permissive cells and from purified SV40 virions. These data reveal the presence of a unique structure of the papovavirus chromatin close to the initiation site of DNA replication.
mesh_terms: D002843:Chromatin / Q000648:ultrastructure; D002874:Chromosome Mapping; D004261:DNA Replication; D004270:DNA, Circular / Q000235:genetics / Q000378:metabolism; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D007700:Kinetics; D011120:Polyomavirus / Q000235:genetics*; D013539:Simian virus 40 / Q000235:genetics*; D014779:Virus Replication
chemical_list: D002843:Chromatin; D004270:DNA, Circular; D004279:DNA, Viral; D004720:Endonucleases