Part:BBa_K2762014
Pasr-B0034-sfGFP
Characterization
The strain that we used is carrying asr promoter, a pH-responsive promoter which is native to E. coli and it could induce transcription in acidic conditions. Besides, we clone a sfGFP gene downstream of this promoter which could express green fluorescent once the promoter has been activated.
In conclusion, when the color of the medium turns from turbid yellow to green, it indicates the pH of the medium is too low so the medium should be changed as it is not suitable for our E. coli to grow.
The asr promoter was first described by Suziedeliene et al. in 1999. They showed that asr is induced under low pH which is about pH 4.8, and it is controlled by the phoBR system. From the article they have published, the promoter is named as acid shock RNA (asr) promoter due to the RNA that has been transcribed after putting the E. coli into a low pH condition.
In 2007 Ogasawara et al2. found out that there is another regulatory system that controlling asr transcription by using SELEX to find the binding sequences of PhoQP-RstBA. Hence the asr promoter is directly controlled by two different systems, the PhoBR system activated through low inorganic phosphate and the RstAB system sensing the pH while it is controlled by PhoQP-system activated by low Mg2+ concentrations.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25INCOMPATIBLE WITH RFC[25]Illegal AgeI site found at 314
- 1000COMPATIBLE WITH RFC[1000]
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