Part:BBa_K4375021

Blue light inducible production of mCherry (BLADE)

This device is meant for the light-inducible production of mCherry (BBa_J18932), a red fluorescent protein. To achieve this, we used a modified arabinose operator system, where the transcription factor, AraC, is engineered to homodimerize upon blue-light illumination instead of arabinose binding. This system is called BLADE, and it is produced under the strong constitutive promoter J23101* (BBa_K4375003).

Characteristics

Figure 1: 1) Blue-light induced mCherry production characterization; A) Blue-light induced mCherry production with our first illumination setup; B) Blue-light intensity dependent mCherry production with our first illumination setup.

Team ELTE has developed two types of illumination devices, both capable of emitting blue light around 450 nm. (To know about them, please refer to our Hardware page) The first is a quite simple device, with whom we could monitor the mCherry production over time at a given light intensity. Fig. 1/A shows the results of this experiment. After 7,5 hours of irradiation (at 37 °C), we observed an 8.25 fold increase in fluorescence, which was significantly less than it was described in the literature. (15x) However, this could be easily explained by the difference between light sources since Romano et. al used an illumination setup which produces an irradiance of 5 W*m^−2. [1] We have not obtained such information about our device yet, therefore, these results cannot be compared exactly. Our other illumination device is capable of irradiating a 96-well plate and is highly programmable. With it, we could investigate the light intensity-dependent nature of our protein production. (Fig. 1/B) We could detect differences between illuminated and dark samples during this experiment, but significantly less than we previously did. This also could be reasoned by the different light sources or the different temperatures which we used for the protein expression. (37 vs. 25 °C) Moreover, we could not put our second device into an incubator, the culture was not as oxygenated as in the first case. Later we hypothesised, that the difference could be explained by the different bacterial culturing protocols, which could affect the number of plasmid copies. The previous measurement was conducted with a freshly transformed culture, but in the other case, we used frozen glycerol bacteria stock. We observed a slight difference between protein productions at different light intensities, although the correlation was not directly proportional. It seemed, over 57% of power there is no substantial difference between samples.

Usage and Biology

Figure 2.:Blue-light inducible mCherry production controlled by BLADE.

This device is a blue light-activatable system, which is based on the BLADE protein. Upon illumination, the BLADE binds to the AraBAD promoter and mCherry is expressed. This allows the monitoring of the protein levels upon blue light illumination.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  INCOMPATIBLE WITH RFC[12]

  Illegal NheI site found at 7
  Illegal NheI site found at 29
  
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal BamHI site found at 1174
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal AgeI site found at 1009
  
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal SapI site found at 991
  

Refernces

Romano, E.; Baumschlager, A.; Akmeriç, E. B.; Palanisamy, N.; Houmani, M.; Schmidt, G.; Öztürk, M. A.; Ernst, L.; Khammash, M.; Di Ventura, B. Engineering AraC to Make It Responsive to Light Instead of Arabinose. Nature Chemical Biology 2021, 17 (7), 817–827. https://doi.org/10.1038/s41589-021-00787-6