Difference between revisions of "Part:BBa K3408011"
 
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<partinfo>BBa_K3408011 short</partinfo>
 
<partinfo>BBa_K3408011 short</partinfo>
  
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This composite part consists of promoter P<sub>liaG</sub> and P<sub>grac</sub>, lacI gene, CⅠ gene, GFP gene and some essential RBS and terminators. Promoter P<sub>liaG</sub> starts transcription process and its transcription production is LacI, which is regulated by IPTG. When bacteria is exposed to medium which is rich in IPTG, bacteria can intake IPTG. IPTG is combined with LacI, then LacI cannot be bound to promoter Pgrac which is specially suppressed by LacI. Therefore, CⅠ repressor protein cannot generate as downstream cⅠ gene cannot transcribe regularly.
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This composite part consists of promoter P<sub>liaG</sub> and P<sub>grac</sub>, <i>lacI</i> gene, <i>CⅠ</i> gene, <i>gfp</i> gene and some essential RBS and terminators. P<sub>liaG</sub> starts transcription process and its expression product is LacI, which is regulated by IPTG.  
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LacI is the transcriptional repressor protein, which could bind to the specific site of P<sub>grac</sub> to inhibit its activity. IPTG can break out this inhibition by prior combination with LacI.
  
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As a result, P<sub>CⅠ</sub> recovers its activity and triggers the downstream transcription of GFP. By checking the expression of GFP, we could verify the feasibility of IPTG induction system, thus guaranteeing the successful culture of our engineered <i>Bacillus subtilis</i>.
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When our engineered bacteria is exposed to medium which is rich in IPTG, engineered bacteria can intake IPTG to trigger the expression of CⅠ repressor protein.
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Therefore, P<sub>CⅠ</sub> is inhibited and GFP could not be expressed.
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By checking the expression of GFP, we could verify the feasibility of IPTG induction system, thus guaranteeing the successful culture of our engineered <i>Bacillus subtilis</i>.
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1. Experimental methods
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1.1.Construction of the expression vector
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The pWB980-DB is digested with enzyme EcoRI and PstI. The target fragment of the promoter, RBS, gene of phytase and terminator of this device are synthesized by the biotechnology company with 6×His tags added. Add EcoRI and PstI restriction sites to both ends of the target fragment respectively. Connect the target fragment to the plasmid vector to construct the expression vector P<sub>liaG</sub>-lacⅠ-P<sub>grac</sub>-CⅠ-P<sub>CⅠ</sub>-GFP.
  
 
Plasmid profile
 
Plasmid profile
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https://2020.igem.org/wiki/images/5/58/T--NAU-CHINA--composite-parts6.1.png
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<html>
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<img src="https://2020.igem.org/wiki/images/5/58/T--NAU-CHINA--composite-parts6.1.png" style="width:40%"/>
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</html>
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Fig.1. The expression vector of device P<sub>liaG</sub>-lacI-P<sub>grac</sub>-CⅠ-P<sub>CⅠ</sub>-GFP
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1.2.Construction and screening of recombinant engineered bacteria
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Using <i>Bacillus subtilis</i> WB800N as the expression host, the secretion expression vector pWB980-DB was transformed by electro-transformation. Inoculate them on LB solid medium coated with 10 μg/mL kanamycin, and incubate them overnight at 37 °C. Send transformants to biotechnology company for sequencing.
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1.3.Characterization experiment
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Take 2 bottles of 50 ml LB liquid medium with 10 μg/mL kanamycin, and inoculate the same amount of recombinant engineered bacteria.
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① After culturing for 3 hours, the test group is cultured with 1 mM IPTG at 37 °C and 200 rpm for 2 hours while the IPTG is not added to control group.
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② Use the fluorescence microscope to observe the presence of fluorescence in the test group and the control group.
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2. Expected results
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Fluorescence can be observed in the negative control group but not be observed in the test group.
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<html>
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<img src="https://2020.igem.org/wiki/images/2/2e/T--NAU-CHINA--composite-partsexperiment8.png" style="width:40%"/>
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</html>
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Fig.2. Expected results: different expressions of fluorescence between the control group and the test group.
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These results are predicted because of the lack of experiment for the COVID-19.
  
 
<!-- Add more about the biology of this part here
 
<!-- Add more about the biology of this part here

Latest revision as of 03:27, 28 October 2020

PliaG-B0034-lacI-Pgrac-B0034-CⅠ-PCⅠ-GFP-B0015

This composite part consists of promoter PliaG and Pgrac, lacI gene, CⅠ gene, gfp gene and some essential RBS and terminators. PliaG starts transcription process and its expression product is LacI, which is regulated by IPTG. LacI is the transcriptional repressor protein, which could bind to the specific site of Pgrac to inhibit its activity. IPTG can break out this inhibition by prior combination with LacI.

When our engineered bacteria is exposed to medium which is rich in IPTG, engineered bacteria can intake IPTG to trigger the expression of CⅠ repressor protein. Therefore, PCⅠ is inhibited and GFP could not be expressed.

By checking the expression of GFP, we could verify the feasibility of IPTG induction system, thus guaranteeing the successful culture of our engineered Bacillus subtilis.


1. Experimental methods

1.1.Construction of the expression vector

The pWB980-DB is digested with enzyme EcoRI and PstI. The target fragment of the promoter, RBS, gene of phytase and terminator of this device are synthesized by the biotechnology company with 6×His tags added. Add EcoRI and PstI restriction sites to both ends of the target fragment respectively. Connect the target fragment to the plasmid vector to construct the expression vector PliaG-lacⅠ-Pgrac-CⅠ-PCⅠ-GFP.

Plasmid profile

Fig.1. The expression vector of device PliaG-lacI-Pgrac-CⅠ-PCⅠ-GFP


1.2.Construction and screening of recombinant engineered bacteria

Using Bacillus subtilis WB800N as the expression host, the secretion expression vector pWB980-DB was transformed by electro-transformation. Inoculate them on LB solid medium coated with 10 μg/mL kanamycin, and incubate them overnight at 37 °C. Send transformants to biotechnology company for sequencing.


1.3.Characterization experiment

Take 2 bottles of 50 ml LB liquid medium with 10 μg/mL kanamycin, and inoculate the same amount of recombinant engineered bacteria.

① After culturing for 3 hours, the test group is cultured with 1 mM IPTG at 37 °C and 200 rpm for 2 hours while the IPTG is not added to control group.

② Use the fluorescence microscope to observe the presence of fluorescence in the test group and the control group.


2. Expected results

Fluorescence can be observed in the negative control group but not be observed in the test group.

Fig.2. Expected results: different expressions of fluorescence between the control group and the test group.


These results are predicted because of the lack of experiment for the COVID-19.

Sequence and Features


Assembly Compatibility:
  • 10
    COMPATIBLE WITH RFC[10]
  • 12
    COMPATIBLE WITH RFC[12]
  • 21
    INCOMPATIBLE WITH RFC[21]
    Illegal BglII site found at 1294
  • 23
    COMPATIBLE WITH RFC[23]
  • 25
    COMPATIBLE WITH RFC[25]
  • 1000
    INCOMPATIBLE WITH RFC[1000]
    Illegal BsaI.rc site found at 2155