Structure Validation of G-Rich RNAs in Noncoding Regions of the Human Genome

We present the rapid biophysical characterization of six previously reported putative G-quadruplex-forming RNAs from the 5 '-untranslated region (5 '-UTR) of silvestrol-sensitive transcripts for investigation of their secondary structures. By NMR and CD spectroscopic analysis, we found that only a single sequence-[AGG](2)[CGG](2)C-folds into a single well-defined G-quadruplex structure. Sequences with longer poly-G strands form unspecific aggregates, whereas CGG-repeat-containing sequences exhibit a temperature-dependent equilibrium between a hairpin and a G-quadruplex structure. The applied experimental strategy is fast and provides robust readout for G-quadruplex-forming capacities of RNA oligomers.