Source:
Generated By: https://synbiohub.org/public/igem/igem2sbol/1
Created by: Sibel Sayiner, Justo Caballero, and Shamik Mascharak
Date created: 2012-12-05 12:00:00
Date modified: 2015-05-08 01:14:05
Heat-->PoPS (with postive feedback loop)
| Types | DnaRegion |
| Roles | engineered_region Composite |
| Sequences | BBa_M36604_sequence (Version 1) |
Description
This composite part is a sensor that focuses on creating a positive feedback loop to increase the PoPS signal for a desired actuator further downstream. In this design, Sigma-32, a sigma factor turned on when E. coli experiences heat shock, is the transcription factor for the htpG Heat Shock Promoter (BBa_J45504). Once active, the inducible promoter allows for, with the assistance of a medium strength bicistronic RBS (BBa_M36405), the transcription of rpoH (BBa_M36888), the sequence for sigma-32. Such a design creates a positive feedback loop, creating more sigma-32 from a small initial heat exposure. This is solely done in order to generate a larger PoPS signal, which would allow for a greater production of one's desired downstream production.Device input is heat exposure. Device output is a PoPS signal.
Notes
It should be noted that E. coli has a built-in negative feedback to sigma-32, such that an abundance of sigma-32 turns off natural sigma-32 production. In regards to our promoter, this behavior leads to a sinusoidal relationship and eventually reaches a steady-state. Moreover, we found that creating a positive feedback loop in our construct increased the likelihood of mutations (making the DNA incredibly hard to synthesize) because the leakiness of the promoter caused a sigma-32 presence even when the cell wasn't under any stress. However, when we were first designing this composite, we wanted to produce significant sigma-32 in order to guarantee high expression of our selected actuator.Source
htpG Heat Shock Promoter and Sequence for Sigma-32 Transcription Factor are from the E. coli genome. The bicistronic RBS is from the BIOFAB database. Find more information at their associated part page.| Access | Instance | Definition |
| public public public | BBa_J45504 BBa_M36405 BBa_M36888 | BBa_J45504 BBa_M36405 BBa_M36888 |
| Sequence Annotation | Location | Component / Role(s) |
| BBa_J45504 BBa_M36405 BBa_M36888 | 1,405 414,501 508,1368 | BBa_J45504 BBa_M36405 BBa_M36888 |