Part:BBa_K2360003
rrnB' terminator+MerR+pMerR
This part is a MerR family operon which can make a specific reponse to mercury ion. We add a strong terminator in 5', so that we can just add a report module in 3' to make a biosensor.
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]
Background
MerR
The MerR family is a group of transcriptional regulators with similar N-terminal helix-turn-helix DNA binding regions and C-terminal effector binding regions that are specific to the effector recognized. The few MerR-like regulators that have been studied experimentally have been shown to activate suboptimal σ70-dependent promoters, in which the spacing between the -35 and -10 elements recognized by the σ factor is greater than the optimal 17±1 bp. So, how does it respond to heavy metal ions? Take MerR-pMerR as an example, it has several processes. 1. In the absence of Hg2+ and MerR, RNA polymerase preferentially transcribes from the merR promoter, increasing the amount of MerR present in the cell.
2. Once MerR binds to merOP, transcription of the MerR promoter is repressed and the DNA becomes bent and unwound at the operator sequence. RNA polymerase is recruited to the mer promoter, forming a ternary complex of DNA, MerR and RNA polymerase. 3. Binding of Hg2+ to one of two binding sites on the MerR make DNA distortion at the centre of the operator which cause the reorientation of the -35 and -10 sequences make them interact with the RNA polymerase σ70 subunit to form an open transcriptional complex and transcription is initiated. [1]
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