Using Distal-Site Mutations and Allosteric Inhibition To Tune, Extend, and Narrow the Useful Dynamic Range of Aptamer-Based Sensors

Here we demonstrate multiple, complementary approaches by which to tune, extend, or narrow the dynamic range of aptamer-based sensors. Specifically, we employ both distal-site mutations and allosteric control to tune the affinity and dynamic range of a fluorescent aptamer beacon. We show that allosteric control, achieved by using a set of easily designed oligonucleotide inhibitors that competes against the folding of the aptamer, allows rational fine-tuning of the affinity of our model aptamer across 3 orders of magnitude of target concentration with greater precision than that achieved using mutational approaches. Using these methods, we generate sets of aptamers varying significantly in target affinity and then combine them to recreate several of the mechanisms employed by nature to narrow or broaden the dynamic range of biological receptors. Such ability to finely control the affinity and dynamic range of aptamers may find many applications in synthetic biology, drug delivery, and targeted therapies, fields in which aptamers are of rapidly growing importance.