Team:XMU-China/CSS/SpryMenuBarHorizontal/css

The aim of this study is to construct a fluorescent digital display device of genetic circuits with synthetic logic gates, which can both display and switch numbers. Similar to electronic circuits, logic regulation operation in cells integrates the extracellular and intracellular signals. We assemble several pairs of promoters and their activators (or repressors) into computing building block of the circuit: PBAD-Arabinose, PcI-CI, and PtetR-TetR. As shown in Figure 1, these computation units act as genetic logic gates perform AND, OR and NOT gates function. In order to light up our digital numbers, we put Green Fluorescent Protein (GFP) in the downstream expression, which is ubiquitous in the field of biological signal protein. Considering that the common types of GFP usually tend to be very stable and hard to "quench", we choose unstable GFP to make our device reusable and convert in a fast speed. This unstable GFP is tagged with a C-terminal extension, which will be recognized and degraded by tail-specific proteases, leading to a short half-life and fast degradation of the protein.Degradation rate should be confined at a suitable range, otherwise the device would either have no light or take a long time to change numbers .

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Fig 2 Coherent type 1 Feed-Forward Loops