title: An endonuclease isolated from Epstein-Barr virus-producing human lymphoblastoid cells.
abstract: An endonuclease has been isolated from human B lymphoblastoid cells that copurifies with an exonucleolytic activity and has been shown to produce double-strand breaks and a high proportion of single-strandedness in phage lambda DNA in vitro. The data are consistent with a model in which single-strand cuts are made by the endonucleolytic activity, possibly in A+T-rich regions of the DNA, followed by creation of single-stranded regions (gaps) precessing from the site of a cut. Generation of overlapping gaps on opposite strands or of a gap opposite a nick would lead to the creation of the banding patterns that we have seen on electrophoretic gels. This endonucleolytic activity copurifies with other enzymes induced by Epstein-Barr virus that relate to the process of viral DNA replication in productively infected cells. However, a more general role is proposed for this class of eukaryotic endonuclease activities. A marked degree of single-strandedness has been found in the replicating DNAs of many eukaryotes, ad these gaps could be generated by endonucleases with associated exonucleolytic activity such as that reported here. This Epstein-Barr virus-induced nuclease activity has been shown to resemble the recBC nuclease isolated from the prokaryote Escherichia coli and also the endonuclease isolated from the eukaryote Chlamydomonas.
mesh_terms: D010582:Bacteriophage lambda; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D004720:Endonucleases / Q000302:isolation & purification / Q000378:metabolism*; D005092:Exonucleases / Q000302:isolation & purification; D004854:Herpesvirus 4, Human / Q000201:enzymology*; D006801:Humans; D013379:Substrate Specificity; D014779:Virus Replication
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004720:Endonucleases; D005092:Exonucleases; D004262:DNA Restriction Enzymes