Part:BBa_K1319001

RFC[25]-compatible dark quencher based on K1319000 (E0030)

This part is a RFC[25] dark quencher that is based upon K1319000 (the RFC[25] version of E0030/EYFP)..

Two mutations were introduced that eliminated fluorescence:

• L90I
• Y145W

References

• Ganesan S, Ameer-Beg SM, Ng TT, Vojnovic B, Wouters FS. A dark yellow fluorescent protein (YFP)-based Resonance Energy-Accepting Chromoprotein (REACh) for Förster resonance energy transfer with GFP. Proc Natl Acad Sci U S A. 2006 Mar 14;103(11):4089-94. Epub 2006 Mar 6. PubMed PMID: 16537489; PubMed Central PMCID: PMC1449651. [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1449651/?report=classic PubMed Central]

Usage and Biology

This protein is designed to be a dark quencher for GFP (E0040) in a FRET system. When used in a fusion protein with GFP it reduces the observed fluorescence of GFP drastically. In the biobrick K1319013 this is realised and the proteins are fused with the linker K1319016 which includes a specific TEV protease (available as K1319004) cleavage site. The fusion of the proteins bring GFP and REACh 1 in proximity to each other which allows GFP and REACh 1 to act as donors and acceptors in a FRET (Förster Energy Transfer System) system. GFPs emission energy is thereby taken up by REACh 1 and released as thermal energy instead of visible light. This eliminates the GFP fluorescence and allows for a release of a strong fluorescence signal if a TEV protease is expressed and the linker is cut. The cutting separates GFP and REACh 1 cancelling the FRET interaction and providing a GFP fluorescence response.

Characterization

In order to characterize K1319001 it was expressed as a fusion protein together with GFP to show its quenching ability. This fusion protein, produced by K1319013, was located on the plasmid backbone pSB3K3. To show that the reduced fluorescence was due to the quenching ability of K1319001 and not based on a faulty expression K1319008 was also introduced into the cells on a pSB1C3 backbone to allow for a double plasmid system. Both constructs were put into E. coli BL21 (DE3) compared to I20260 and B0015. B0015 was used as a negative control and I20260 was chosen as a positive control due to the expressed GFP being identical to the GFP being expressed in the fusion protein of K1319013 and having the same promoter, RBS, Terminator and plasmid backbone.

The double plasmid system, B0015 and I20260 were measured in biological triplicates and after 2 h one set of triplicates of each of the three systems were induced with 50 µl 100mM IPTG in their 50 ml culture (500 ml shake flasks). The following graph shows the resulting fluorescence adjusted for the measured optical density to account for difference in growth of the cultures and to only show the fluorescence per cell.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]