1.7.2.3 the torECA promoter, and to a lesser extent the torYZ and dmsABC promoters, are active during symbiotic colonization of juvenile Euprymna scolopes, transcriptional regulation, overview 687424 1.7.2.3 the trimethylamine N-oxide reductase respiratory system is encoded by the torECAD operon, a three-gene cluster, torSTR, encoding a complex two-component regulatory system is present downstream of the torECAD operon, introduction of the torSTR gene cluster into Escherichia coli shows that this regulatory gene cluster is involved in trimethylamine N-oxide induction of the torE promoter, the torR operator site is required for induction of the tor structural promoter, TorS of Escherichia coli , the trimethylamine N-oxide sensor of Escherichia coli is able to transphosphorylate TorR of Shewanella oneidensis, the trimethylamine N-oxide response regulator of Shewanella oneidensis 392780