Part:BBa_K1132002:Design
XOR gate with recombinases switching gene regulatory sequences
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21INCOMPATIBLE WITH RFC[21]Illegal BamHI site found at 1
- 23COMPATIBLE WITH RFC[23]
- 25INCOMPATIBLE WITH RFC[25]Illegal NgoMIV site found at 122
- 1000INCOMPATIBLE WITH RFC[1000]Illegal BsaI site found at 142
Illegal BsaI.rc site found at 331
Design Notes
This XOR gate was built with one promoter- one terminator surrounded by the Bxb1 integrase sites and the Tp901.1 integrase sites. This system is designed to be activated only in the presence of excusively one recombinases (transcription of the output gene). The switch is permanent.
The input signals for this gate are the production of either one or both integrases Bxb1 and Tp901.1. The output can be choosen at will by assembling this biobrick to any ORF containing an RBS site. We also designed a test Biobrick of the gate (BBa_K1132032) with the RFP protein as output.
This gate can be used in any regulation system, provided that the recombinases are assembled following the promoter of your choice with your specific regulations requirements. For example, if you want to activate the gate in presence of aTc or AHL but not with both, you just have to put the recombinase after the promoter activated by LuxR/AHL (BBa_R0065) and the promoter activated by aTc under the repression of TetR (BBa_R0040).
Even a relatively small amount of recombinases can switch the DNA fragments. Therefore, it is really important to control the recombinases expression with a well-locked promoter. You can look at our specially designed regulation sequence (riboregulator) to get as low as possible any undesired expression and production of the recombinases (BBa_K1132005, BBa_K1132006, BBa_K1132007, BBa_K1132008, BBa_K1132042).
In the present design, the strength of the promoter does not allow high level expression of the controlled output. However, change to stronger promoter than P7 should potentially lead to better expression levels.
Resetting the gate to its basal state requires a series of excisases capable of switching back the sequences to their native state.
The same type of design was used to build a AND gate (BBa_K1132001).
Design of the gate :
For this gate, restrcition sites have been add between the promoter to change it esaly if necessary. Effectively, as shown during the caracterisation, the P7 promoter does not allow high level expression of the output. It could be interesting to change the promoter by a stronger one.
Source
later