Part:BBa_K4656003

Lrp

The Lrp is a gene encoding leucine reactive protein, which is expressed by E. coli itself. It mediates a global response to leucine. Exogenous leucine affects the expression of a number of different operons, and Lrp mediates this effect for at least some of these operons. For example, it is a regulator of the branched-chain amino acid transport genes. In our project, Lrp dimerizes with butyrate, binds to pPchA promoter, and further helps to produce pchA.

Usage and Biology

LRP, as a component of the natural FIM system of E. coli, is a fimS regulator. Both LRP and IHF (Integrated Host factor) may act to regulate the actual inversion events through an involved DNA-binding protein complex. In addition, there is the OFF-to-ON inhibitory protein papB and many other hypothesized and known regulators that directly act on LRP. During the course of the project, the FIM system can be considered. (Additional background on FIM systems can be found in the references [1])

Experimental results

In our project, it serves as the butyrate sensor to respond to the change in butyrate concentration, thereby activating downstream gene expression. During our experiments, we wondered whether it is possible to enhance the expression of Lrp in the engineered bacteria to increase the sensitivity of the PchA promoter to butyrate.

We simultaneously introduced the pBAD33 plasmid carrying Lrp and the pet-28a plasmid containing the receptor into Escherichia coli. Bacteria that received only the receptor plasmid but not the Lrp plasmid were used as a control group. We compared the sensitivity of these two groups to butyrate.

Both groups were cultured in 0mM, 10mM, and 20mM sodium butyrate, and the results demonstrated that increased expression of Lrp did enhance the sensitivity of the PchA promoter to butyrate.

Reference

[1]. Schwan W. R. (2011). Regulation of fim genes in uropathogenic Escherichia coli. World journal of clinical infectious diseases, 1(1), 17–25. https://doi.org/10.5495/wjcid.v1.i1.17

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 30
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]