Figure 1
From: Rational design of modular circuits for gene transcription: A test of the bottom-up approach
Gene circuits. Repressor (A) and Reporter (B) plasmids. Boxes highlight the parts that could be used as independent elements to tune the circuit outcome in a modular framework. As a proof of principle of the modular architecture, we created nine different gene circuits, combining three different operator sequences, O1, O2 and Os, in two plasmids. (C) Gene circuit in cells transformed with both the plasmids. (D) Sequences of the three operator sites. Bold characters are used for the central G-C base pair in the naturally occurring operator sites O1 and O2. The left and right half operator sites in O1 and O2 are pseudo-symmetric, lower-case characters highlight the deviations from perfect symmetry. The base pairs that are different between the operators O1 and O2 are underlined in the O2 sequence. The artificial operator site Os was defined removing the central base pair G-C and creating a perfectly symmetric sequence based on the left half of the operator O1. The affinity to lactose repressor of the three operator sites O1, O2 and Os spans a range of over two orders of magnitude [27, 28], which allows the analysis of the system behavior under wide changes of the parameters values.