title: A potent cell-active allosteric inhibitor of murine DNA cytosine C5 methyltransferase.
abstract: The major DNA cytosine methyltransferase isoform in mouse erythroleukemia cells, Dnmt1, exhibits potent dead-end inhibition with a single-stranded nucleic acid by binding to an allosteric site on the enzyme. The previously reported substrate inhibition with double-stranded substrates also involves binding to an allosteric site. Thus, both forms of inhibition involve ternary enzyme-DNA-DNA complexes. The inhibition potency of the single-stranded nucleic acid is determined by the sequence, length, and most appreciably the presence of a single 5-methylcytosine residue. A single-stranded phosphorothioate derivative inhibits DNA methylation activity in nuclear extracts. Mouse erythroleukemia cells treated with the phosphorothioate inhibitor show a significant decrease in global genomic methylation levels. Inhibitor treatment of human colon cancer cells causes demethylation of the p16 tumor suppressor gene and subsequent p16 re-expression. Allosteric inhibitors of mammalian DNA cytosine methyltransferases, representing a new class of molecules with potential therapeutic applications, may be used to elucidate novel epigenetic mechanisms that control development.
authors.affiliation: Department of Chemistry and Biochemistry and Program in Biochemistry and Molecular Biology, University of California, Santa Barbara 93106, USA.
authors.forename: James
authors.initials: J
authors.lastname: Flynn
authors.forename: Jing-Yuan
authors.initials: JY
authors.lastname: Fang
authors.forename: Judy A
authors.initials: JA
authors.lastname: Mikovits
authors.forename: Norbert O
authors.initials: NO
authors.lastname: Reich
mesh_terms: D000495:Allosteric Site; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017931:DNA Primers; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D051379:Mice
chemical_list: D017931:DNA Primers; D004791:Enzyme Inhibitors; D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases