Cellular Arithmetic Logic Unit Using Toehold Switches

Abstract

Since the demonstration of primitive studies on molecular computing over two decades ago, modern synthetic biologists are now seeking for more complex artificial cellular functions. In this regard, RNA is one of promising materials for synthetic circuit due to its fully designable Watson-Crick base pairing and various structure prediction bioinformatic tools. While several arithmetic logics are implemented using diverse components [1,2], RNA-only operation has not yet been achieved. Here, we show RNA-only binary operation of XOR gate and cellular arithmetic logic operation, specifically half-adder. By the integration of orthogonal NIMPLY gates developed from de-novo-designed toehold switches [3], we can successfully demonstrate XOR gate which have higher dynamic range compared to conventional systems. To achieve comprehensive screening of functional antisense RNAs, we employed automatic design pipeline for selected toehold switch pairs. Then, basic binary calculator was constructed based on our XOR gate by combining with AND gate. We have further planned to build more sophisticated molecular computing devices, such as Neural network, by using multi-input multi-output features of binary calculators.