Introduction

As previously described in the design of the switch, each half switch contains a nut site followed by a terminator, as well as an anti-terminator. The roles of these parts are to increase the stability of the current state and thereby also the robustness of the switch. As the PRM promoter is not very well repressed by the GogR/GtgR repressors, transcription is promoted even in their presence. If transcription was allowed to continue to the anti-repressor located on the inactive half of the switch, the switch could change state spontaneously. The terminator is placed in front of the anti-repressor to ensure that this does not happen. The anti-terminator of the active state is expressed, allowing continued transcription past the terminator.