Differential Binding Mode of a Phenanthroline-Based Metal Complex to a DNA or RNA Telomeric Sequence

RNA G-quadruplexes have been recently proposed as physiologically relevant structures in cellular processes which suggests they represent attractive novel drug targets. Up-to-date, limited information of their interactions with small molecules is available. In particular, no systematic comparative analysis of the DNA vs RNA recognition processes has been performed. Here, we investigated the RNA G-quadruplex binding properties of a phenanthroline-based metal complex, (P115)Ni(II), known to efficiently recognize the DNA telomeric sequence. We showed that one ligand molecule can be sandwiched between two RNA G-quadruplex units. Conversely, this binding mode is not occurring using the DNA counterpart as the target sequence