Supramolecular-Assembly-Enabled Synthetic mRNA Switch for Efficient and Accurate Cell Fate Control

Synthetic mRNA switches are promising tools capable of regulating target protein levels (output) in response to specific molecular signals (input). Conventional synthetic mRNA switch commonly consists of two domains: an input sensing module and a output coding module. The sensing domain interacts with input via noncovalent interactions to repress output production. Leaky expression of output signal is an innate limitation of conventional synthetic mRNA switch. Here, we engineered a novel readout control module to alleviate the signal noise generated by leaky output expression. This readout control module is based on aptamer-protein interaction. An array of aptamers is used as scaffolding to assemble inactive output protein. Only in the absence of input, ample amount of output protein can saturate the aptamer array to form functional protein assemblies. While in the presence of input, the leaky output protein production is insufficient to trigger assembly formation. Synthetic mRNA switches carrying this readout control module can sense different input with higher signal-to-noise ratio, offering efficient and accurate output signal production. This novel design combines chemistry and synthetic biology principles to offer a generally applicable synthetic mRNA switch model, featuring the near-complete sequestering of output signal noise, stronger input sensitivity, and a wider output operation range. With these prominent properties, we believe this novel switch model can efficient and accurate orthogonal control of cell fate, bringing enormous potentials in building complex synthetic mRNA circuits for next-generation diagnostic and therapeutic purposes.