Difference between revisions of "Part:BBa K3771018"
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<br>For the IFN-γ induction assay, OFP is used as the reporter to compare the strengths of the <i>lacI</i> promoter (<a href="https://parts.igem.org/Part:BBa_R0010" alt="" target="_blank">BBa_R0010</a>) and the <i>ompA</i> promoter (<a href="https://parts.igem.org/Part:BBa_K3771011" alt="" target="_blank">BBa_K3771011</a>). Therefore, two plasmids with the respective promoters were constructed, while also containing the <i>pspA</i> promoter (<a href="https://parts.igem.org/Part:BBa_K3071013" alt="" target="_blank">BBa_K3071013</a>) required for the activation of the IFN-γ sensing system. | <br>For the IFN-γ induction assay, OFP is used as the reporter to compare the strengths of the <i>lacI</i> promoter (<a href="https://parts.igem.org/Part:BBa_R0010" alt="" target="_blank">BBa_R0010</a>) and the <i>ompA</i> promoter (<a href="https://parts.igem.org/Part:BBa_K3771011" alt="" target="_blank">BBa_K3771011</a>). Therefore, two plasmids with the respective promoters were constructed, while also containing the <i>pspA</i> promoter (<a href="https://parts.igem.org/Part:BBa_K3071013" alt="" target="_blank">BBa_K3071013</a>) required for the activation of the IFN-γ sensing system. | ||
− | First, the <i>pspA</i> promoter synthesized by IDT was amplified by PCR and then ligated to ofp gene (<a href="https://parts.igem.org/Part:BBa_K156009" alt="" target="_blank">BBa_K156009</a>), already present in our starting pUC cloning vector, resulting in <i>P<sub>pspA</sub>-ofp</i> (<a href="https://parts.igem.org/Part:BBa_K3771014" alt="" target="_blank">BBa_K3771014</a>). To construct <i>P<sub>lacI</sub>-ompA/oprF</i> (<a href="https://parts.igem.org/Part:BBa_K3771015" alt="" target="_blank">BBa_K3771015</a>), <i>lacI</i> promoter in our starting pUC cloning vector, was ligated with the <i>ompA/oprF</i> fragment (<a href="https://parts.igem.org/Part:BBa_K3771009" alt="" target="_blank">BBa_K3771009</a>) synthesized by IDT. We then cloned the <i>ompA</i> promoter sequence from <i>E. coli</i> MG1655 and replaced <i>lacI</i> promoter with ompA promoter, resulting in <i>P<sub>ompA</sub>-ompA/oprF</i> (<a href="https://parts.igem.org/Part:BBa_K3771016" alt="" target="_blank">BBa_K3771016</a>). <br> | + | First, the <i>pspA</i> promoter synthesized by IDT was amplified by PCR and then ligated to ofp gene (<a href="https://parts.igem.org/Part:BBa_K156009" alt="" target="_blank">BBa_K156009</a>), already present in our starting pUC cloning vector, resulting in <i>P<sub>pspA</sub>-ofp</i> (<a href="https://parts.igem.org/Part:BBa_K3771014" alt="" target="_blank">BBa_K3771014</a>). To construct <i>P<sub>lacI</sub>-ompA/oprF</i> (<a href="https://parts.igem.org/Part:BBa_K3771015" alt="" target="_blank">BBa_K3771015</a>), <i>lacI</i> promoter in our starting pUC cloning vector, was ligated with the <i>ompA/oprF</i> fragment (<a href="https://parts.igem.org/Part:BBa_K3771009" alt="" target="_blank">BBa_K3771009</a>) synthesized by IDT. We then cloned the <i>ompA</i> promoter sequence from <i>E. coli</i> MG1655 and replaced <i>lacI</i> promoter with <i>ompA</i> promoter, resulting in <i>P<sub>ompA</sub>-ompA/oprF</i> (<a href="https://parts.igem.org/Part:BBa_K3771016" alt="" target="_blank">BBa_K3771016</a>). <br> |
<br>Both the <i>P<sub>lacI</sub>-ompA/oprF</i> and <i>P<sub>ompA</sub>-ompA/oprF</i> fragments were double digested and ligated to the <i>P<sub>pspA</sub>-ofp</i> vector, respectively, which formed the final plasmids required for the IFN-γ assay: <i>P<sub>pspA</sub>-ofp-P<sub>lacI</sub>-ompA/oprF</i> and <i>P<sub>pspA</sub>-ofp-P<sub>ompA-ompA/oprF</i> plasmids.<br> | <br>Both the <i>P<sub>lacI</sub>-ompA/oprF</i> and <i>P<sub>ompA</sub>-ompA/oprF</i> fragments were double digested and ligated to the <i>P<sub>pspA</sub>-ofp</i> vector, respectively, which formed the final plasmids required for the IFN-γ assay: <i>P<sub>pspA</sub>-ofp-P<sub>lacI</sub>-ompA/oprF</i> and <i>P<sub>pspA</sub>-ofp-P<sub>ompA-ompA/oprF</i> plasmids.<br> |
Revision as of 01:52, 22 October 2021
PpspA-OFP-PompA-OmpA/OprF
Description
This composite part is part of a plasmid used in the IFN-γ induction assay to test the function of the IFN-γ sensing system. It consists of the ompA/oprF gene regulated by the ompA promoter (PompA-ompA/oprF) and the orange fluorescent protein (OFP) gene regulated by the pspA promoter (PpspA-ofp).
Biology
![](https://2021.igem.org/wiki/images/a/af/T--NCKU_Tainan--ompA_oprF.gif)
Figure. 1 Structure of OmpA/OprF chimeric protein
To allow E. coli to detect IFN-γ in the human gut, we constructed an OmpA/OprF chimeric protein designed by Aurand and March[1]. The OmpA/OprF chimeric protein consists of OmpA protein from E. coli and a smaller section of OprF protein from P. aeruginosa.
![](https://2021.igem.org/wiki/images/e/e6/T--NCKU_Tainan--pspA_ofp.gif
)
Figure 2. Mechanism of IFN-γ sensing system
The ompA promoter facilitates the constitutive expression of chimeric OmpA/OprF. Binding of IFN-γ to chimeric OmpA/OprF induces the response of the phage shock protein (Psp) system[1], a highly conserved stress response system in enterobacteria[2]. Signal transduction from the outer membrane to the inner membrane activates the pspA promoter, initiating expression of OFP.
Usage
For the IFN-γ induction assay, OFP is used as the reporter to compare the strengths of the lacI promoter (BBa_R0010) and the ompA promoter (BBa_K3771011). Therefore, two plasmids with the respective promoters were constructed, while also containing the pspA promoter (BBa_K3071013) required for the activation of the IFN-γ sensing system. First, the pspA promoter synthesized by IDT was amplified by PCR and then ligated to ofp gene (BBa_K156009), already present in our starting pUC cloning vector, resulting in PpspA-ofp (BBa_K3771014). To construct PlacI-ompA/oprF (BBa_K3771015), lacI promoter in our starting pUC cloning vector, was ligated with the ompA/oprF fragment (BBa_K3771009) synthesized by IDT. We then cloned the ompA promoter sequence from E. coli MG1655 and replaced lacI promoter with ompA promoter, resulting in PompA-ompA/oprF (BBa_K3771016).
Both the PlacI-ompA/oprF and PompA-ompA/oprF fragments were double digested and ligated to the PpspA-ofp vector, respectively, which formed the final plasmids required for the IFN-γ assay: PpspA-ofp-PlacI-ompA/oprF and PpspA-ofp-PompA-ompA/oprF plasmids.
Characterization
![](https://2021.igem.org/wiki/images/2/20/T--NCKU_Tainan--composite_pspA_OFP_pOmpA_ompA_oprF.jpg)
Figure 3. Confirmation of construction by PCR. M: Marker; Lane 1: pspA promoter (~218bp); Lane 2: ompA promoter (~309 bp); Lane 3: ompA/oprF (~1110bp)
Human IFN-γ of concentrations 300 pM and 600 pM was added to bacteria culture to induce the system. OFP expression (RFU) was recorded using a microplate reader and normalized by OD600. As shown in figure 11, starting at around 12 hours after induction, OFP expression increased dramatically.
![](https://2021.igem.org/wiki/images/a/a3/T--NCKU_Tainan--proof_of_concept_5.jpg)
Figure 4. OFP expression of PpspA-ofp-PompA-ompA/oprF
As presented in figure 5, at 12 hours after induction, sample 2 (PpspA-ofp-PompA-ompA/oprF) with the addition of 600 pM IFN-γ had higher OFP expression than that of sample 1 (PpspA-ofp-PlacI-ompA/oprF). Since ompA promoter stimulates higher protein expression than lacI promoter, we decided to incorporate the ompA promoter in our final biobrick to regulate the expression of cs.
![](https://2021.igem.org/wiki/images/5/5a/T--NCKU_Tainan--proof_of_concept_45.jpg)
Figure 5. OFP expression of PpspA-ofp-PlacI-ompA/oprF (sample 1) and OFP expression of PpspA-ofp-PompA-ompA/oprF (sample 2) at 12 hours after IFN-γ induction
References
1. Aurand TC, March JC. Development of a synthetic receptor protein for sensing inflammatory mediators interferon‐γ and tumor necrosis factor‐α. Biotechnology and Bioengineering. 2016;113(3):492-500. doi:10.1002/bit.25832
2. Darwin AJ. The phage-shock-protein response. Molecular Microbiology. 2005;57(3):621-628. doi:10.1111/j.1365-2958.2005.04694.x
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21INCOMPATIBLE WITH RFC[21]Illegal BglII site found at 12
Illegal BamHI site found at 2158 - 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]