Regulatory

Part:BBa_K4119078

Designed by: Tao Jiang   Group: iGEM22_NJTech_China   (2022-10-12)


PvgbF3

PvgbF3 is an oxygen inducible promoter.PvgbF3 was modified based on the Pvgb constitutive promoter from Vitreoscilla.PvgbF3 were applied in E.coli successfully.


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Result:

Adjusting the distance between FNR binding site and the -35 region of promoter vgb fine tunes the inhibitory effect of oxygen on the promoter.

Fig.9 Construction of the recombinant plasmid for pMTL-PvgbF7-bs2

By consulting the literature and consulting the authors [2], we learned that the distance between the FNR binding site and the -35 region of the promoter has a large impact on promoter transcriptional regulation. To adjust the distance of FNR binding site from the -35 region, we used site-directed mutagenesis. Megaprimer mutation technique was used to separate the FNR binding site from the -35 region by, changing the distance between the FNR binding site to 3bp and 7bp from -35 region, while changing the sequence from the second half of the FNR binding site and the -35 region to more conservative sequences [2,] with higher expressive effects, and reducing the interval speacer between-35 and-10 region to 17bp. The plasmid pMTL-Pvgb-bs2 was extracted from recombined E. coli CA434 pMTL-Pvgb-bs2 constructed previously. In this experiment, the megaprimers were obtained by PCR technique using the plasmid pMTL-Pvgb-bs2 as the template, and then the mutant plasmid was obtained by PCR using those megaprimers to amplify the plasmid.

Figure 10. Expression effect of pMTL-Pvgb-F7-bs2 at different oxygen concentratio

By analyzing the fluorescence intensity data, it can be found that the increase in the distance between the FNR binding site and the -35 region of the promoter could result in a certain decrease in its expression effect. Under aerobic and microaerobic conditions, the modified promoter (Pvgb-F7) was separately 0.267 and 0.422 folds of the controlled group (Pvgb). The modified promoter still has the regulatory effect brought by FNR and its based oxygen-related biosensor system, which induction ratio increased to 6.28, compared with 3.97 of Pvgb as control.

Sequence and Features


Assembly Compatibility:
  • 10
    COMPATIBLE WITH RFC[10]
  • 12
    COMPATIBLE WITH RFC[12]
  • 21
    COMPATIBLE WITH RFC[21]
  • 23
    COMPATIBLE WITH RFC[23]
  • 25
    COMPATIBLE WITH RFC[25]
  • 1000
    COMPATIBLE WITH RFC[1000]
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