Optimal Census by Quorum Sensing
Fig 3
Models for the regulation of the monitor protein (MP) expression.
A. In the TF regulation model, AI molecules induce the production of MPs by allosterically regulating the transcription factor (TF), which only binds to its cognate DNA regulatory sequence when complexed with AI. B. In the sRNA regulation model, a TF positively regulates a small regulatory RNA (sRNA) that represses MP expression. In both models, the expression of MP is positively regulated by binding of AIs to the TF and MP proteins regulate their own expression. For strong sRNA-mRNA pairing, sRNA regulation reduces the stochasticity in MP expression compared with TF regulation. The internal feedback regulates the transcription of the MP mRNA for TF regulation, whereas it regulates the sRNA level for sRNA regulation.