The use of light to investigate and modulate DNA and RNA conformations

We report the use of light for two distinct kinds of investigation of the conformational changes of, respectively, DNA and RNA. First, 'Deoxyribosensors' are a class of DNA constructs that incorporate aptamers, and which report the binding of a ligand to the aptamer by attenuating the conformational/stacking relationship of two constituent DNA double helices within the sensor. Such attenuations can be monitored as electrical outputs via a light irradiation protocol. Second, RNA aptamers were selected for the specific binding of one but not the other isomer of different photochromic switch compounds. One such RNA aptamer, specific for binding the 'closed' isomer of a dihydropyrene compound, was used to create a highly effective, light-sensitive, RNA-cleaving ribozyme. Such ribozymes and riboswitches should find broad utility for the light-mediated control of gene expression within living cells and organisms.