Hierarchical architecture of the genetic regulatory network. Each ellipse refers to a mechanism of transcriptional regulation, including: (i) transcription factors; (ii) early termination of transcription (T-box, L-box, G-box, A-box, S-box, TRAP); (iii) proteins involved in transcriptional regulation (RtpA). Each hexagon refers to a mechanism of translational regulation, including: (i) small RNA (SR1); (ii) peptide leaders (Plead). The arrow indicates the causality of the regulation. A regulator with a curved black arc indicates that it is subject to auto-regulation. Blue, magenta and dark red regulators have a metabolite, a PTS component, and an ion, respectively, as effector. The effector of brown regulators is unknown. Black regulators have no effector.