title: Importance of the O6 position of guanine residues in the binding of DNA methylase to DNA.
abstract: Methylation of Micrococcus lysodeikticus DNA by purified DNA methylase isolated from L1210 leukaemia cells is potently and specifically inhibited by both hetero and homoribo and deoxyribopolynucleotides containing guanine residues. The inhibitory effect is unaffected by chain length, but is abolished when the O6 residue of guanine is substituted as in poly[d(O6MeG)]20. Potent inhibition is also shown by polyinosinic and polyxanthylic acids, but not by polyadenylic acid or by heteropolymers containing adenine and thymine. These results suggest that the 6-position of the purine nucleus is important in binding of the DNA methylase to a particular region of the DNA duplex and that the hydrogen bonding properties of this group are important in enzyme recognition.
authors.affiliation: CRC Experimental Chemotherapy Group, Aston University, Birmingham, U.K.
authors.forename: P A
authors.initials: PA
authors.lastname: Hepburn
authors.forename: M J
authors.initials: MJ
authors.lastname: Tisdale
mesh_terms: D001665:Binding Sites; D015254:DNA Modification Methylases / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D015226:Dinucleoside Phosphates / Q000378:metabolism; D007700:Kinetics; D008745:Methylation; D008837:Micrococcus / Q000378:metabolism; D011068:Poly G / Q000378:metabolism
chemical_list: D015254:DNA Modification Methylases; D004269:DNA, Bacterial; D015226:Dinucleoside Phosphates; D011068:Poly G; C015772:CpG dinucleotide; C026628:poly(dG)