PhyB-PIF3 system
| Type: | Synthetic promoter; Optogenetic promoter |
| Other names: | / |
| Description: | PhyB (Phytochrome B) and its interaction partner, PIF3 (Phytochrome-Interacting Factor 3) protein are constituents of the first used optogentic system that was used to control non-neuronal processes1. While it paved the way toward optogenetic control of cellular processes, PhyB-PIF3 has the disadvantage that it requires the exogenous addition of the chromophore phycocyanobilin (PCB), which is not produced by most eukaryotes other than plants. For transcriptional control, PhyB and PIF3 are fused to the Gal4 transcriptional activation domain and the Gal4 DNA binding domain, respectively1,2. When bound to PCB and activated by red light (≈ 650 nm) PhyB binds PIF3. This brings the transcriptional activation and DNA binding domains close and leading to the expression of the GAL family of genes including GAL1. In the presence of far-red light (≈ 740 nm), PhyB changes conformation again and dissociates from PIF3. Since the spectra of activating and deactivating light overlap, PhyB is maintained in a dynamic equilibrium between the two states whose ratio depends on the wavelengths of the illumination.3 In addition to the disadvantage of requiring exogenous PCB, the system also affects galactose metabolism in budding yeast when used for transcriptional induction with a split Gal4 transcription factor. |
| Organism of origin: | The light-responsive PhyB and PIF3 proteins come from Arabidospis thaliana. The DNA binding and transcriptional activation domains come from the budding yeast (Saccharomyces cerevisiae) transcription factor Gal4. |
| Available on Addgene: | / |
| Inducing condition: | Red light (≈ 650 nm) |
| Repressing condition: | Far-red light (≈ 740 nm) |
Promoter name Leakiness [% maxGAL1] tau-on [min] tau-off [min] Maximal induction level [maxGAL1] Stationary induction level [maxGAL1] Initial induction speed [0.001 maxGAL1/min] Degradation rate [0.01/min]
PhyB-PIF3 0.17 13.3 < 1 0.17 0.12 1.1 0.9
References:
- Shimizu-Sato, S., Huq, E., Tepperman, J. M. & Quail, P. H. A light-switchable gene promoter system. Nat. Biotechnol. 20, 1041–1044 (2002). https://doi.org/10.1038/nbt734
- Pathak, G. P., Strickland, D., Vrana, J. D. & Tucker, C. L. Benchmarking of optical dimerizer systems. ACS Synth. Biol. 3, 832–838 (2014). https://doi.org/10.1021/sb500291r
- Quail, P. H. Phytochromes. Curr. Biol. 20, R504–R507 (2010). https://doi.org/10.1016/j.cub.2010.04.014