Part:BBa_K1688012

BBa_J61051, NahR with nahR and sal promoters (Pr and Psal), codes for the inducible repressor NahR, which suppresses Psal in the absence of salicylate. This biobrick makes it possible to regulate the expression of the red fluorescent protein dTomato. Figure 1. dTomato expressed in E. coli DH5-alpha with NahR/Psal promoter system, induced by 1mM salicylate.

Usage and Biology

The dTomato protein is a fluorescent protein dimer, created by direct evolution of the wild-type DsRed, from Discosoma sp. (Shaner et al, - Improved monomeric red, orange and yellow fluorescent proteins derived from Discosoma sp. red fluorescent protein, 2004). The dTomato protein is a fluorescent dimer protein that emits orange-red light when it is excited by green-yellow light. It is preferable to use – especially in self-made fluorometry tests – because the excitation wavelengths and the emission wavelengths don't overlap as much as in other fluorescent proteins. The dTomato excitation peak is at 554 nm and 50% of it is at 510 nm. Also, its emission peak is at 581 nm and its 50% emission at 629 nm (Figure 2).

Figure 2. Excitation (blue curve) and emission (red curve) spectra for the dTomato fluorescent protein (the graph is designed with the following tool: https://www.chroma.com/spectra-viewer)

References

Nathan C Shaner, Robert E Campbell, Paul A Steinbach, Ben N G Giepmans, Amy E Palmer & Roger Y Tsien. “Improved monomeric red, orange and yellow fluorescent proteins derived from Discosoma sp. red fluorescent protein”, 2004