title: Dnmt3a-CD is less susceptible to bulky benzo[a]pyrene diol epoxide-derived DNA lesions than prokaryotic DNA methyltransferases.
abstract: Benzo[a]pyrene (B[a]P) is a well-characterized environmental polycyclic aromatic hydrocarbon pollutant. In living organisms, B[a]P is metabolized to the genotoxic anti-benzo[a]pyrene diol epoxide that reacts with cellular DNA to form stereoisomeric anti-B[a]PDE-N(2)-dG adducts. In this study, we explored the effects of adduct stereochemistry and position in double-stranded DNA substrates on the functional characteristics of the catalytic domain of murine de novo DNA methyltransferase Dnmt3a (Dnmt3a-CD). A number of 18-mer duplexes containing site-specifically incorporated (+)- and (-)-trans-anti-B[a]PDE-N(2)-dG lesions located 3'- and 5'-adjacent to and opposite the target cytosine residue were prepared. Dnmt3a-CD binds cooperatively to the DNA duplexes with an up to 5-fold greater affinity compared to that for the undamaged DNA duplexes. Methylation assays showed a 1.7-6.3-fold decrease in the methylation reaction rates for the damaged duplexes. B[a]PDE modifications stimulated a nonproductive binding and markedly favored substrate inhibition of Dnmt3a-CD in a manner independent of DNA methylation status. The latter effect was sensitive to the position and stereochemistry of the B[a]PDE-N(2)-dG adducts. The overall effect of trans-anti-B[a]PDE-N(2)-dG adducts on Dnmt3a-CD was less detrimental than in the case of the prokaryotic methyltransferases we previously investigated.
authors.affiliation: Chemistry Department, Moscow State University, Moscow 119991, Russia.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Lukashevich
authors.forename: Vladimir B
authors.initials: VB
authors.lastname: Baskunov
authors.forename: Maria V
authors.initials: MV
authors.lastname: Darii
authors.forename: Alexander
authors.initials: A
authors.lastname: Kolbanovskiy
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Baykov
authors.forename: Elizaveta S
authors.initials: ES
authors.lastname: Gromova
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000494:pharmacology*; D020134:Catalytic Domain; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018736:DNA Adducts / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D004852:Epoxy Compounds / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D011387:Prokaryotic Cells / Q000201:enzymology; D011485:Protein Binding
chemical_list: D018736:DNA Adducts; C000715535:Dnmt3a protein, mouse; D004852:Epoxy Compounds; D001564:Benzo(a)pyrene; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A