Part:BBa_K1586003
EsxB toehold switch J23100
Usage and Biology
A toehold switch is a type of RNA molecule known as a riboregulator/riboswitch. It is able to detect the presence of a specific ssRNA molecule (termed the 'trigger RNA') which has a sequence complementary to its switch region through base pairing. If the correct RNA molecule is detected, the protein coding region of the toehold is expressed.
A toehold switch is unique in comparison to other types of riboswitches as it is completely synthetic, and therefore easier to engineer and standardise. The fact that the toehold switch can be modified means that the switch region can be easily changed to detect any given trigger RNA molecule, and the protein coding region can be swapped for any desired reporter protein most suitable for its application.
As shown by Exeter iGEM 2015, toehold switches can be used to detect specific RNA molecules in a cell-free system. In addition to this, the plasmid DNA encoding the toehold switch can be transformed into cells in order to ascertain whether a gene is being expressed (through detection of its mRNA). The applications of this technology can range from a research tool (e.g. detection of secreted RNA in cell supernatant, detection of gene expression, etc.), through to more commercial/medical applications such as diagnostic testing.
The Part
Part K1586003 encodes for an adaptable and standardised synthetic toehold switch. This toehold switch was built to contain a standard promoter (J23100), RBS (B0032), and GFP (E0040). It was designed to be used in a diagnostic test, with an initial target of the EsxB gene mRNA. EsxB encodes for Esat6 and is involved in the pathogenicity of Mycobacterium bovis. For more on this issue and the use of toehold switches in diagnostic testing, visit Exeter iGEM 2015's wiki (http://2015.igem.org/Team:Exeter).
Characterisation
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12INCOMPATIBLE WITH RFC[12]Illegal NheI site found at 7
Illegal NheI site found at 30 - 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000INCOMPATIBLE WITH RFC[1000]Illegal BsaI.rc site found at 793
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