title: NMR solution structures of LNA (locked nucleic acid) modified quadruplexes.
abstract: We have determined the NMR solution structures of the quadruplexes formed by d(TGLGLT) and d(TL4T), where L denotes LNA (locked nucleic acid) modified G-residues. Both structures are tetrameric, parallel and right-handed and the native global fold of the corresponding DNA quadruplex is retained upon introduction of the LNA nucleotides. However, local structural alterations are observed owing to the locked LNA sugars. In particular, a distinct change in the sugar-phosphate backbone is observed at the G2pL3 and L2pL3 base steps and sequence dependent changes in the twist between tetrads are also seen. Both the LNA modified quadruplexes have raised thermostability as compared to the DNA quadruplex. The quadruplex-forming capability of d(TGLGLT) is of particular interest as it expands the design flexibility for stable parallel LNA quadruplexes and shows that LNA nucleotides can be mixed with DNA or other modified nucleic acids. As such, LNA-based quadruplexes can be decorated by a variety of chemical modifications. Such LNA quadruplex scaffolds might find applications in the developing field of nanobiotechnology.
authors.affiliation: Nucleic Acid Center, Department of Chemistry, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Jakob T
authors.initials: JT
authors.lastname: Nielsen
authors.forename: Khalil
authors.initials: K
authors.lastname: Arar
authors.forename: Michael
authors.initials: M
authors.lastname: Petersen
mesh_terms: D020029:Base Pairing; D002236:Carbohydrate Conformation; D004247:DNA / Q000737:chemistry*; D054856:G-Quadruplexes; D006147:Guanine / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D009691:Nucleic Acid Denaturation; D009841:Oligonucleotides; D016376:Oligonucleotides, Antisense / Q000737:chemistry*; D012996:Solutions; D013696:Temperature
chemical_list: D009841:Oligonucleotides; D016376:Oligonucleotides, Antisense; D012996:Solutions; C477371:locked nucleic acid; D006147:Guanine; D004247:DNA