title: Site-directed spin labeling of DNA reveals mismatch-induced nanometer distance changes between flanking nucleotides.
abstract: Multiple forms of DNA damages such as base modifications, double-strand breaks, and mispairings are related to inheritable diseases, cancer, and aging. Here, the structural changes of duplex DNA upon incorporation of mismatched base pairs are examined by EPR spectroscopy. Two ethynyl-7-deaza-2'-deoxyadenosine residues separated by two nucleotides were incorporated in DNA and functionalized with 4-azido-2,2,6,6-tetramethyl-piperidine-1-oxyl (4-azido TEMPO) by the click reaction. Mismatches such as dT·dT or dA·dA mispairs were positioned between these two spin labels in DNA duplexes. Pulse EPR experiments reveal that the mismatch-induced local conformational changes are transmitted to the flanking nucleotides and that the impact of this mismatch depends on the nearest neighbor environment.
authors.affiliation: Department of Physics, University Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany.
authors.forename: Dorith
authors.initials: D
authors.lastname: Wunnicke
authors.forename: Ping
authors.initials: P
authors.lastname: Ding
authors.forename: Frank
authors.initials: F
authors.lastname: Seela
authors.forename: Heinz-Jürgen
authors.initials: HJ
authors.lastname: Steinhoff
mesh_terms: D020137:Base Pair Mismatch; D057930:Click Chemistry; D003497:Cyclic N-Oxides / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D013113:Spin Labels; D014372:Tubercidin / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D003497:Cyclic N-Oxides; D009841:Oligonucleotides; D013113:Spin Labels; C053222:2'-deoxytubercidin; D004247:DNA; D014372:Tubercidin; C003959:TEMPO