title: N4,5-dimethylcytosine, a novel hypermodified base in DNA.
abstract: Successive enzymatic modification of DNA by two methyltransferases that recognize identical or overlapping sequences and normally target either 5- or N4-position of the same cytosine residue, can lead to the formation of a doubly methylated base--N4,5-dimethylcytosine. Implications of such enzymatic "permethylation" of cytosine on the structure and interactions of DNA are examined.
authors.affiliation: Laboratory of Biological DNA Modification, Institute of Biotechnology, Graiciuno 8, LT-2028 Vilnius, Lithuania.
authors.forename: Saulius
authors.initials: S
authors.lastname: Klimasauskas
authors.forename: Ruta
authors.initials: R
authors.lastname: Gerasimaite
authors.forename: Giedrius
authors.initials: G
authors.lastname: Vilkaitis
authors.forename: Saulius
authors.initials: S
authors.lastname: Kulakauskas
mesh_terms: D003596:Cytosine / Q000031:analogs & derivatives / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D019175:DNA Methylation
chemical_list: C476816:N4,5-dimethylcytosine; D003596:Cytosine; D004247:DNA