title: DNA methylation by N-methyl-N-nitrosourea: methylation pattern changes in single- and double-stranded DNA, and in DNA with mismatched or bulged guanines.
abstract: The detection of abnormal DNA base pairing arrangements and conformations is chemically probed in synthetic 32P-end-labeled deoxyribonucleotide oligomers using N-methyl-N-nitrosourea (MNU) and 2,12,-dimethyl-3,7,11,17-tetraazabicyclo-[11.3.1]heptadeca-1 -[17],2,11,13,15 pentaene-Ni (II) (Ni-complex) with KHSO5. The DNA targets studied are single-stranded (s-s) DNA, double-stranded (d-s) DNA, d-s DNA with G-G, G-A and G-T mismatches, d-s DNA with a single bulged G and d-s DNA with two bulged G's. The effect of the non-Watson--Crick structures on the formation of N7-methylguanine (N7-MeG) by MNU and the oxidation of G by Ni-complex is reported along with the Tm's and circular dichroism spectra of the different duplex oligomers. The results for MNU and Ni-complex show that the qualitative and quantitative character of the cleavage patterns at a G3 run change with the nature of the abnormal base pairing motif. Based on the DNA substrates studied, the results indicate that a combination of reagents which report electronic and steric perturbations can be a useful approach to monitor DNA mismatches and bulges.
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha 68198-6805.
authors.forename: R L
authors.initials: RL
authors.lastname: Wurdeman
authors.forename: M C
authors.initials: MC
authors.lastname: Douskey
authors.forename: B
authors.initials: B
authors.lastname: Gold
mesh_terms: D001345:Autoradiography; D001483:Base Sequence; D002942:Circular Dichroism; D004247:DNA / Q000187:drug effects* / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000187:drug effects* / Q000378:metabolism; D006147:Guanine / Q000737:chemistry*; D006358:Hot Temperature; D008745:Methylation; D008770:Methylnitrosourea / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009692:Nucleic Acid Heteroduplexes / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism
chemical_list: D004277:DNA, Single-Stranded; D009692:Nucleic Acid Heteroduplexes; D006147:Guanine; D008770:Methylnitrosourea; D004247:DNA