Dynamics of G-Quadruplex Formation under Molecular Crowding

G-quadruplex (G4) structures assemble from guanine-rich DNA sequences and are believed to regulate several key cellular processes. G4 formation and conformational interconversions are well-established to occur dynamically in vitro. However, a clear understanding of G4 formation dynamics in cells as well as under conditions mimicking the cellular environment is missing. To fill this gap, we have investigated the G4 dynamics in molecularly crowded solutions, thus replicating the effect of the excluded volume present in cells. The results show that the volume exclusion exerted by large crowding agents accelerates the rate of G4 formation by at least an order of magnitude, leading to significant G4 stabilization. Extrapolation from our experimental data predicts crowding-induced G4 stabilization by more than 3 kcal/mol, under crowding levels found in the cellular environment. Such effects are likely to be important for G4-driven regulatory functions.