Part:BBa_K2257007

This part is used for the detection of formaldehyde.

Formaldehyde sensor sequence

Design

This protein FrmR acts as regulator of protein FrmAB. FrmA and FrmB are two proteins that are participating in the detoxication of formaldehyde in E.coli.
FrmR can form DNA-protein cross-links with a special promotor PfrmAB to prevent activating downstream gene transcription.
Formaldehyde is able to covalently modify protein FrmR, inhibiting its function, so when formaldehyde exists, promotor PfrmAB is capable of activating downstream gene transcription by the destruction of the promoter PfrmAB- the protein FrmR cross-link.

Experiments

We have successfully proved that this part is specifically induced by formaldehyde.

Figure 1. Fluorescence test of various aldehydes using recombinant bioluminescent Escherichia coli BL21

Figure 2. Response fluorescence intensity for recombinant bioluminescent Escherichia coli BL21 to various formaldehyde concentration

When treated with formaldehyde, the color change is visible to naked eyes.

Figure 3. The photograph of recombinant Escherichia coli liquid treated without and with formaldehyde

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal XhoI site found at 226
  Illegal XhoI site found at 462
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal SapI.rc site found at 520
  

The sequence is composed of PfrmR, gene frmR, flag tag, PfrmAB, gene RFP.
When the pathway works, we can see that the E.coli turns to red with naked eyes at the presence of formaldehyde.
The fluorescence intensity of protein RFP and the depth of the color in naked eyes are both in positive correlation with the concentration of formaldehyde within the tolerable range.