Fig. 1: Schematic for the optical control of gene expression by G4switch.
From: Optical control of gene expression using a DNA G-quadruplex targeting reversible photoswitch
a, A G-tetrad, comprising four Hoogsteen hydrogen-bonded guanines, stabilized by a central monovalent cation (top) following a preference order of potassium (K+) > sodium (Na+) > lithium (Li+), and a parallel intramolecular G4 structure composed of stacked G-tetrads (bottom). b, Schematic diagram for the concept of optically controlling gene expression using a photoswitchable G4 ligand G4switch. Upon blue (405 nm) or green (525 nm) light illumination, G4switch can be switched ‘ON’ or ‘OFF’, respectively, in live cells to enable it to reversibly bind to endogenous DNA G4s and inhibit the gene expression, thus achieving spatiotemporal control of gene expression. TSS, transcription start site.
