Part:BBa_K2500003

pTlpA: Temperature-Responsive Promoter
TlpA is a constitutively expressed repressor protein, which binds to promoter pTlpA and blocks the start of transcription of genes downstream of pTlpA.¹ The binding to the promoter is reversibly deactivated by temperatures above 37 °C with full deactivation at 45 °C. Parameters influencing the final expression of the genes downstream of pTlpA are the constitutive promotor and RBS of TlpA itself and the RBS of the pTlpA downstream genes. By tweaking these sequences, it should be possible to obtain a wide range of leakiness and fold changes (fold-change up to 200-fold).

Figure 1: The pTlpA promoter regulates the lysis step of CATE. The promoter is bound and inhibited by TlpA repressor proteins below 37 °C, thereby blocking the release of the cytotoxic compound at body temperature. To fully activate the promoter and thus cell lysis, the desired area is heated to 45 °C with focused ultrasound.

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]

Usage and Biology

TlpA is transcriptional repressor protein and thermosensor found in Salmonella typhimurium which can undergo a temperature-dependent conformational change. At temperatures below 37 °C, its N-terminal DNA-binding domain inhibits transcription downstream of the pTlpA promoter. By heat-shocking the cells at temperatures between 37 - 45 °C, its C-terminal coiled-coil domain quickly uncoils, shifting it from active dimer to inactive monomer. In 2016, it was shown that the sharpness and temperature range of the thermal switch can be successfully tuned.

References

1. Piraner, Dan I., et al. "Tunable thermal bioswitches for in vivo control of microbial therapeutics." Nature chemical biology 13.1 (2017): 75-80.