Synthetic Gene Networks That Count

Abstract

Synthetic gene networks can be constructed to emulate digital circuits and devices, giving one the ability to program and design cells with some of the principles of modern computing, such as counting. A cellular counter would enable complex synthetic programming and a variety of biotechnology applications. Here we report two complementary synthetic genetic counters in E. coli that can count up to three induction events, the first comprised of a riboregulated transcriptional cascade and the second of a recombinase-based cascade of memory units. These modular devices permit counting of varied user-defined inputs over a range of frequencies and can be expanded to count higher numbers.