title: d(CGGTGGT) forms an octameric parallel G-quadruplex via stacking of unusual G(:C):G(:C):G(:C):G(:C) octads.
abstract: Among non-canonical DNA secondary structures, G-quadruplexes are currently widely studied because of their probable involvement in many pivotal biological roles, and for their potential use in nanotechnology. The overall quadruplex scaffold can exhibit several morphologies through intramolecular or intermolecular organization of G-rich oligodeoxyribonucleic acid strands. In particular, several G-rich strands can form higher order assemblies by multimerization between several G-quadruplex units. Here, we report on the identification of a novel dimerization pathway. Our Nuclear magnetic resonance, circular dichroism, UV, gel electrophoresis and mass spectrometry studies on the DNA sequence dCGGTGGT demonstrate that this sequence forms an octamer when annealed in presence of K(+) or NH(4)(+) ions, through the 5'-5' stacking of two tetramolecular G-quadruplex subunits via unusual G(:C):G(:C):G(:C):G(:C) octads.
authors.affiliation: Dipartimento di Chimica delle Sostanze Naturali, University of Naples Federico II, Naples, Italy. nicola.borbone@unina.it
authors.forename: Nicola
authors.initials: N
authors.lastname: Borbone
authors.forename: Jussara
authors.initials: J
authors.lastname: Amato
authors.forename: Giorgia
authors.initials: G
authors.lastname: Oliviero
authors.forename: Valentina
authors.initials: V
authors.lastname: D'Atri
authors.forename: Valérie
authors.initials: V
authors.lastname: Gabelica
authors.forename: Edwin
authors.initials: E
authors.lastname: De Pauw
authors.forename: Gennaro
authors.initials: G
authors.lastname: Piccialli
authors.forename: Luciano
authors.initials: L
authors.lastname: Mayol
mesh_terms: D001483:Base Sequence; D019281:Dimerization; D054856:G-Quadruplexes; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular