title: Plasmid-controlled variation in the content of methylated bases in bacteriophage lambda deoxyribonucleic acid.
abstract: The N(6)-methyladenine (MeAde) and 5-methylcytosine (MeC) contents in deoxyribonucleic acid (DNA) of bacteriophage lambda has been analyzed as a function of host specificity. The following facts have emerged: (i) lambda grown on strains harboring the P1 prophage contain ca. 70 more MeAde residues/DNA molecule than lambda grown either in the P1-sensitive parent, or in a P1 immune-defective lysogen which does not confer P1 modification; (ii) lambda grown on strains harboring the N-3 drug-resistance factor contain ca. 60 more MeC residues/DNA molecule than lambda grown on the parental strain lacking the factor; (iii) lambda grown in Escherichia coli B strains is devoid of MeC, whereas lambda grown in a B (N-3) host contains a high level of MeC; (iv) the MeAde content in lambda DNA is not affected by the N-3 factor. These results suggest that P1 controls an adenine-specific DNA methylase, and that the N-3 plasmid controls a cytosine-specific DNA methylase. The N-3 factor has been observed previously to direct cytosine-specific methylation of phage P22 DNA and E. coli B DNA in vivo; in vitro studies presented here demonstrate this activity.
mesh_terms: D000225:Adenine / Q000032:analysis / Q000378:metabolism; D001483:Base Sequence; D002474:Cell-Free System; D002499:Centrifugation, Density Gradient; D002854:Chromatography, Paper; D003090:Coliphages / Q000032:analysis / Q000254:growth & development / Q000378:metabolism*; D003596:Cytosine / Q000032:analysis / Q000378:metabolism; D004269:DNA, Bacterial; D004279:DNA, Viral / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology; D005111:Extrachromosomal Inheritance; D005827:Genetics, Microbial; D008242:Lysogeny; D008715:Methionine / Q000378:metabolism; D008745:Methylation; D014316:Tritium
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral; D014316:Tritium; D003596:Cytosine; D008715:Methionine; D000225:Adenine