title: Studies on an endonuclease activity associated with bacteriophage T7 DNA-membrane complex.
abstract: Infection of Escherichia coli with bacteriophage T7 results in the formation of an endonuclease which is selectively associated with the T7 DNA-membrane complex. A specificity of association with the complex is indicated by the finding that the enzyme is completely resolved from a previously described T7 endonuclease I. When membrane complexes containing (3)H-labeled in vivo synthesized DNA are incubated in the standard reaction mixture a specific cleavage product is formed which is about one-fourth the size of T7 DNA. The endonuclease associated with the complex produces a similar cleavage product after extensive incubation with native T7 DNA or T7 concatemers. Degradation of concatemers occurs by a mechanism in which the DNA is converted to molecules one-half the size of T7. This product is in turn converted to fragments one-fourth the size of mature phage DNA. The endonuclease is not present in membrane complexes from uninfected cells or cells infected with gene 1 mutants. The enzyme activity is, however, present in cells infected with mutants defective in T7 DNA synthesis or maturation.
mesh_terms: D002462:Cell Membrane; D002501:Centrifugation, Zonal; D003090:Coliphages / Q000254:growth & development*; D004267:DNA Viruses / Q000254:growth & development; D004279:DNA, Viral; D004720:Endonucleases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D009154:Mutation; D014779:Virus Replication
chemical_list: D004279:DNA, Viral; D004720:Endonucleases