Types | DnaRegion
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Roles | engineered_region
Composite
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Sequences | BBa_K2112001_sequence (Version 1)
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Description
The plasmid could be co-transformed into E.coli BL21(DE3) with another plasmid containing a lacI coding sequence. Then with the inducing by IPTG (a compound), target protein could be expressed in high efficiency.
T7 promoter is a strong promoter to launch the transcription procedure.
Lac operator DNA sequence could bind a protein named LacI coded by a lacI DNA sequence which located in another plasmid. This process stop the transcription of the target gene (opdA). So in our study, we add a compound named IPTG to the culture medium. IPTG could bind LacI protein, so that the structure of LacI will be changed and could not bind to lac operator DNA sequence any more. And the target gene opdA could be transcribed and translated.
His-tag sequence (fused in N-terminal of target protein OpdA) consisted of five to six histidines, which could bind to Nickel metal ions. So with a special resin chelated with nickel metal ions, we can purify the expressed OpdA protein easily.
When??the??degradation??finishes,??ultraviolet??light??or??natural??light??is??given??to??shed??on??the??bacteria,??and??thus??the??RecA??repair??gene??inside??the??bacteria??is??activated.??The??product??of??this??gene??can??activate??RecA??(SOS)??promoter.??Thus??the??bacteria??begin??to??express??suicide??gene??ccdB,??which??leads??the??bacteria??to??dying??automatically??in??order??to??avoid??the??secondary??pollution??on??vegetables??and??fruits??posed??by??genetically??engineered??bacteria.
Notes
The his-tag can allow us to purify the protein after the bacteria secrete it, so that if the project can be use in real life, the posibility of risk can be limited by giving the users the purified protein to degrade organophosphorous instead of using the bacteria.
Source
The ccdB gene is found by other teams, we use it in our part to achieve the goal.