Biomolecular resource utilization in elementary cell-free gene circuits

We present a detailed dynamical model of the behavior of transcription-translation circuits in vitro that makes explicit the roles played by essential molecular resources. A set of simple two-gene test circuits operating in a cell-free biochemical `breadboard' validate this model and highlight the consequences of limited resource availability. In particular, we are able to confirm the existence of biomolecular `crosstalk' and isolate its individual sources. The implications of crosstalk for biomolecular circuit design and function are discussed.