By assembled with their activators/repressors upstream, inducible promoters may detect the existence of inducers such as arabinose and salicylate. The promoters here act as Small Molecule Sensor. Two favourite promoter parts involved have been very well characterized.
(Learn more about the Small Molecule Sensor)
Fig1. The mechanism of the AND Gate J Christopher Anderson, Christopher A Voigt and Adam P Arkin (2007) Environmental signal integration by a modular AND gateMolecular Systems Biology 3:133
Our AND Gate is designed by J. Anderson, C. Voigt and A. Arkin (Molecular Systems Biology 3:133, 2007). We reconstructed the AND gate according to the principle of standard assembly, and finally greatly improved its efficiency. The AND gate senses small molecules as inputs and integrates the signals to activate T7 promoter, so as to trigger the expression of downstream gene. Different promoters are used to drive the expression of T7ptag and SupD tRNA to make this AND Gate. It really needs a great amount of work in order to find one qualified AND Gate out of tens of AND Gates. The figure on the top left demonstrates the mechanism of our AND Gate. The figure on the top right denotes one of the best AND Gates we achieved in the summer. These two AND Gate parts have been well characterized.
(Learn more about the AND Gate 1 design and AND Gate 2 design)