title: Recognition of foldback DNA by the human DNA (cytosine-5-)-methyltransferase.
abstract: In order to specify the recognition requirements of the human DNA (cytosine-5-)-methyltransferase, two isomeric 48mers were synthesized so as to link a long block of DNA with a shorter complementary block of DNA through a tether consisting of five thymidine residues. These isomeric foldback molecules, differing only in the location of the 5-methyldeoxycytosine, were shown to be unimolecular, to contain a region of duplex DNA, and to contain a region of single-stranded DNA. When used as substrates for the DNA methyltransferase, only one of the isomers was methylated. A comparison of the structures of the two isomers allows us to begin to define the potential sites of interaction between the enzyme and the three nucleotides forming a structural motif consisting of 5-methyldeoxycytosine, its base-paired deoxyguanosine, and a deoxycytosine 5' to the paired deoxyguanosine.
authors.affiliation: City of Hope National Medical Center, Duarte, California.
authors.forename: S S
authors.initials: SS
authors.lastname: Smith
authors.forename: R G
authors.initials: RG
authors.lastname: Lingeman
authors.forename: B E
authors.initials: BE
authors.lastname: Kaplan
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D008745:Methylation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D013379:Substrate Specificity
chemical_list: D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases