Part:BBa_K3790014
The simplest form of dps promoter, a strong σS promoter
Introduction
RNA polymerase in E.coli. relies on combined with σ factors to recognize promoter sequences. Although σ70 factor is responsible for the transcription of most of the genes in the genome of E.coli.. E.coli. has other six kinds of alternative σ factors that are triggered in stressful conditions. By switching σ factors, the cell can dramatically change the whole transcription pattern in order to express specific proteins to help itself survive the bad environment.
Among the six alternative σ factors, only σS factor recognizes DNA sequences that are very similar to the typical promoter sequences recognized by σ70. Therefore, it’s usually thought that σS promoters rely on upstream elements, which are other protein-binding DNA sequences distributed upstream, to show their dependence on σS factors.
We mentioned that there’s no standard and well-characterized σS promoter in iGEM community. Therefore, we tested the attributes of the core regions of several σS promoters and selected those can be recognized by σS factors independently. Among them, the core region of the promoter controlling the expression of dps in E.coli. shows highest strength as a σS promoter.
Usage and Biology
The sequence regulated by this part shows high transcription rate in stressful conditions, such as carbon starvation. Typically, the expression of protein regulated by this part will be dramatically enhanced during platform stage, which means it can help efficiently express proteins when the density of bacteria is super high, thus reaching high amount of total expression.
WT T7 phage naturally has a gene product, gp5.7 (BBa_ Z0141), that acts as an efficient inhibitor of σS-dependent transcription. Therefore, you can simultaneously control the expression of all the proteins whose transcription is regulated by this part by controlling the expression of gp5.7, which brings lots of new possibilities to the construction of gene circuits.
Future development
This part is the simplest form of dps promoter. It’s short and can function as a σS promoter independently, so it can be freely fused with other regulatory parts such as operators to create new parts with new properties.
Characterization
Growth curve & GFP expression curve measurement
Methodology
We transform dps promoter
Reference
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
//promoter
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