title: Is the DNA of virus T7 methylated?
abstract: DNA modification of T7 wild type and of T7 M-mutants was studied by determining the percentage of 5-methylcytosine (5MC)/cytosine (C) and N6-aminopurine (6MA)/adenine (A) and by evaluating the plating efficiencies of restriction-sensitive T7 M-mutants on modifying and non-modifying host strains. Only 0.03% adenine and 0.02% cytosine were methylated in the DNA of T7 wild type as well as in T7 M-mutants, which was independent of the host DNA methylation (30- to 50-fold higher). The restriction of T7 M-mutants, determined from the plating efficiencies, was not altered on modifying or non-modifying hosts. These results indicate that host-specific modification is blocked during T7 development and that this is not due to the M-protein.
mesh_terms: D000225:Adenine / Q000032:analysis; D003596:Cytosine / Q000032:analysis; D004269:DNA, Bacterial / Q000032:analysis; D004279:DNA, Viral / Q000032:analysis*; D004926:Escherichia coli / Q000032:analysis; D008745:Methylation; D009154:Mutation; D009690:Nucleic Acid Conformation; D010641:Phenotype; D013604:T-Phages / Q000032:analysis* / Q000254:growth & development
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral; D003596:Cytosine; D000225:Adenine