title: The insertion of two 8-methyl-2'-deoxyguanosine residues in tetramolecular quadruplex structures: trying to orientate the strands.
abstract: In this article, we report a structural study, based on NMR and CD spectroscopies, and molecular modelling of all possible d(TG(3)T) and d(TG(4)T) analogues containing two 8-methyl-2'-deoxyguanosine residues (M). Particularly, the potential ability of these modified residues to orientate the strands and then to affect the folding topology of tetramolecular quadruplex structures has been investigated. Oligodeoxynucleotides (ODNs) TMMGT (T12) and TMMGGT (F12) form parallel tetramolecular quadruplexes, characterized by an all-syn M-tetrad at the 5'-side stacked to all-anti M- and G-tetrads. ODNs TMGMT (T13) and TMGGMT (F14) form parallel tetramolecular quadruplexes, in which an all-anti G core is sandwiched between two all-syn M-tetrads at the 5'- and the 3'-side. Notably, the quadruplex formed by T13 corresponds to an unprecedented structure in which the syn residues exceed in number the anti ones. Conversely, ODN TGMGMT (F24) adopts a parallel arrangement in which all-anti G-tetrads alternate with all-syn M-tetrads. Most importantly, all data strongly suggest that ODN TMGMGT (F13) forms an unprecedented anti-parallel tetramolecular quadruplex in which G and M residues adopt anti and syn glycosidic conformations, respectively. This article opens up new understandings and perspectives about the intricate relationship between the quadruplex strands orientation and the glycosidic conformation of the residues.
authors: Dipartimento di Chimica delle Sostanze Naturali, Università degli Studi di Napoli Federico II, Via D. Montesano 49, I-80131 Napoli, Italy.
authors: Antonella
authors: A
authors: Virgilio
authors: Veronica
authors: V
authors: Esposito
authors: Giuseppe
authors: G
authors: Citarella
authors: Antonietta
authors: A
authors: Pepe
authors: Luciano
authors: L
authors: Mayol
authors: Aldo
authors: A
authors: Galeone
mesh_terms: D002942:Circular Dichroism; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D054856:G-Quadruplexes; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009691:Nucleic Acid Denaturation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry
chemical_list: C104538:8-methyl-2'-deoxyguanosine; D009838:Oligodeoxyribonucleotides; D003849:Deoxyguanosine