Fig. 1.

AND gate design based on σ54-dependent hrpR/hrpS. Two environment-responsive promoters, P1 and P2 that acts as inputs to drive the transcription of hrpR and hrpS, and respond to the small molecules I 1 and I 2. The transcription hrpL promoter is turned on when HrpR and Hrps are present. It binds to the upstream activator sequence to remodel the closed σ54-RNAP-hrpL transcription complex through ATP hydrolysis. GFP was used as output while RBS for fine tuning. Figure reproduced with permission from Nature (Wang et al. 2011) © 2011 Macmillan Publishers Ltd