Part:BBa_K2824007

lldPRD operon promoter-Luxs-Lldr

Long Description

LLDR can inhibit or activate lldPRD. We believe that the binding of LLDR to lldPRD operon promoter under the condition of lactic acid deficiency may lead to DNA translation and transcriptional inhibition. The binding of L- lactic acid to LLDR can promote conformation change, thus destroy the DNA cycle and form a transcriptional open complex (Figure 1). At the same time, the LuxS gene can be regulated to activate the quorum sensing system of Escherichia coli, through which the lactic acid sensor can be combined with the quorum sensing.

This part is one of the components of the final lactate sensing system. When it exists with LsrA promoter-GFP part, the whole system works: GFP is barely expressed when there is no lactic acid, In the presence of lactic acid, the expression of GFP varied with time and concentration of lactic acid (Figure 2). The peak value of fluorescence signal of LsrA promoter-GFP part, was found in the condition of low concentration of lactic acid and shorter reaction time. Finally, we can conclude that the addition of Escherichia coli allelopathy makes LLDPRD operon promoter more sensitive to lactic acid.

Characterization

It can be seen from the figure that the peak value of fluorescence signal exists when the concentration of lactic acid is 1mMol/L, compared with the concentration of 2mMol/L in the absence of Lldr (Figure 3). This suggests that the addition of Lldr increases the ability of the system to sense lactic acid, that is, to become more sensitive to lactic acid.

Figure1: Characterization of Lldr under different concentrations of lactic acid and IPTG. Lane 1, IPTG 0mM, lactic acid 0mM, O-LuxS-lldR; Lane 2, IPTG 0.5mM, lactic acid 0mM, O-LuxS-lldR; Lane 3, IPTG 1mM, lactic acid 0mM, O-LuxS-lldR; Lane 4, IPTG 0mM, lactic acid 2mM, O-LuxS-lldR; Lane 5, IPTG 0.5mM, lactic acid 2mM, O-LuxS-lldR; Lane 6, IPTG 1mM, lactic acid 2mM, O-LuxS-lldR

Figure 2:lldPRD operon promoter-LuxS-Lldr work with LsrA-GFP

Figure 3:lldRPD operon promoter-LuxS vs lldRPD operon promoter-LuxS-Lldr

Sequence and Features

Assembly Compatibility:

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

  Illegal BamHI site found at 505
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal AgeI site found at 603
  Illegal AgeI site found at 1442
  
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal BsaI.rc site found at 335