Recognition of foldback DNA by the human DNA (cytosine-5-) methyltransferase

• Published in: Biochemistry (Easton) Vol. 31; no. 3; pp. 850 - 854
• Main Authors: Smith, Steven S, Lingeman, Robert G, Kaplan, Bruce E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 28.01.1992
• Subjects: 550201 - Biochemistry- Tracer Techniques; AMINES; Analytical, structural and metabolic biochemistry; AUTORADIOGRAPHY; AZINES; Base Sequence; BASIC BIOLOGICAL SCIENCES; Biological and medical sciences; BIOSYNTHESIS; CARBON-GROUP TRANSFERASES; CYTOSINE; DNA; DNA (Cytosine-5-)-Methyltransferases - metabolism; DNA - chemistry; DNA - metabolism; ENZYMES; Enzymes and enzyme inhibitors; Female; Fundamental and applied biological sciences. Psychology; HETEROCYCLIC COMPOUNDS; Humans; ISOMERS; Kinetics; MATHEMATICAL MODELS; METHYL TRANSFERASES; Methylation; Models, Molecular; MOLECULAR MODELS; Molecular Sequence Data; Nucleic Acid Conformation; NUCLEIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; Placenta - enzymology; Pregnancy; PROTEINS; PYRIMIDINES; Substrate Specificity; SYNTHESIS; TRANSFERASES; Human; Sequence specificity; Nucleotide sequence; Enzyme; DNA; DNA (cytosine-5-)-methyltransferase; Methylation; Recognition
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00118a030

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.