Part:BBa_K4375004

BLADE (light-responsive AraC transcription factor)

BLADE is a modified AraC transcription factor engineered to react to blue light instead of arabinose. The AraC’s arabinose binding domain was swapped to a homodimerizing Vivid domain. Upon blue light illumination, the protein dimerizes and the AraBAD promoter becomes active.

Usage and Biology

Figure 1: Schematic diagram showing the dimerization of the BLADE transcription factor.

BLADE protein is produced from AraC by exchanging the dimerization domain of AraC with a light-inducible dimerization domain. The switching of this engineered AraC from monomer to dimer is controlled with light. In its monomeric form, the engineered AraC would contact the high-affinity I1 half-site16, but not the low-affinity I2 half-site, needed to recruit the RNA polymerase. For the light-triggered dimerization domain Vivid (VVD) domain was selected, which has often been successfully used to control, with light, the dimerization of proteins of interest. VVD senses blue light via the flavin adenine dinucleotide (FAD) chromophore. Blue light triggers the formation of a cysteinyl-flavin adduct, which generates a new hydrogen-bond network that releases the N terminus (N-terminal cap) from the protein core and restructures it, creating a new dimerization interface.

Figure 2: Diagram showing how BLADE works as a promoter.

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]

References

https://www.nature.com/articles/s41589-021-00787-6.pdf