| Types | DnaRegion
|
| Roles | Coding
CDS
|
| Sequences | BBa_K212001_sequence (Version 1)
|
Description
In our system, the Tar-EnvZ (or Taz) chimera protein is used to indicate and signal the presence of aspartate as a chemical ligand. The native form of Tar, found in E. coli, has three domains: a periplasmic ligand binding receptor domain, a transmembrane domain, and an intracellular kinase domain. When aspartate binds to the receptor domain, the kinase domain subsequently transduces a message by phosphorylating CheA and CheY, which orients the bacteria's chemotaxis machinery (i.e. flagellae) towards the aspartate source. In the Taz construct, however, the kinase domain is omitted and the receptor and signal transduction domains of Tar are ligated to the kinase domain of EnvZ, natively an osmolarity sensor kinase-phosphotransferase. Through the kinase activity of EnvZ, this chimeric protein phosphorylates transcription factor OmpR, which subsequently activates transcription of the OmpC gene (or whatever is under the OmpC promoter).
Notes
This is a chimeric two-component transduction system, so we had to be careful to avoid cross-talk by making sure that EnvZ phosphorylates OmpR only.
Source
Tar-EnvZ (Taz) is a chimera protein, manufactured by Inouye, et al. We obtained the gene from his lab and Biobricked it. Taz comprises of the aspartate chemoreceptor region of Tar, the transmembrane region of Tar, and the intracellular kinase region of EnvZ. The genes were fused by digesting both with NdeI and ligating the overlapping ends together. The cut site is between amino acids H256 and M257.
