Team:NEU China B/Improve
BBa_k2824006:T7-lldPRD operon promoter-GFP
LLDPRD promoter can sense the presence of lactic acid, in the absence of lactic acid, only a lower background level
of expression, but in the presence of lactic acid can open gene expression. We integrated the GFP reporter gene
into downstream this promoter to respond to the presence of lactic acid. In order to improve the GFP expression, we
integrated a strong promoter, T7, into the upstream of lldPRD region.
This part is constructed based on the part lldRO1-plldR-lldRO2 (BBa_k82000) . lldRO1-plldR-lldRO2 part is a lactic
acid regulated promoter that is open to gene transcription in the presence of lactic acid. It can effectively
improve the expression of the target gene and detect whether the target gene is expressed or not. At the same time,
it can accurately determine the amount of the target gene. This allows the overall work of our system to be
reflected in digital form.
Improve the Characterization of BBa_k82000
In the following figure, we compared the expression of lldPRD operon promoter-GFP and T7-lldPRD operon
promoter-GFP. The T7 promoter could enhance gene expression when the concentration of lactic acid was less than 1 m
mol/L. Considering that the lactate concentration in yogurt is generally no more than 1m mol/L, the conclusion can
given that the T7 promoter can enhance the signal intensity for our experiments (Figure 1).
Figure 1:lldPRD operon promoter-GFP vs T7-lldPRD operon promoter-GFP
BBa_k2824008:Lldr-T7-lldPRD operon promoter-GFP
The aim of this part is using llDPRD promoter to activate downstream GFP reporter gene expression under different
lactic acid concentration inductions and this operon is repressed without lactic acid induction. Briefly, LLdR
repression protein specifically binds to llDPRD promoter and impedes downstream gene expression, while lactic acid
enables to antagonize and replace LLdR protein to activate llDPRD promoter (Figure 1). In order to improve the GFP
expression, we integrated a strong promoter, T7, into the upstream of lldPRD region.
This part is constructed based on the part lldRO1-plldR-lldRO2 (BBa_k82000). lldRO1-plldR-lldRO2 part is a lactic
acid regulated promoter that is open to gene transcription in the presence of lactic acid. Comparing with the
T7-lldPRD operon promoter-GFP part, the improvement of this part is that the LLDR is added to part and placed under
the control of two promoters respectively to form a double expression regulatory system. This comparison with the
two plasmids working together is more convenient for testing the success of the system.
Improve the Characterization of BBa_k82000
We can easily find that the Lldr-T7-lldPRD operon promoter-GFP part are in a higher level of expression comparing
to the lldPRD operon promoter-GFP when the lactate concentration is lower than nearly 1.5 mM. Considering that the
lactate concentration in yogurt is generally no more than 1 mM, the conclusion can give that the T7 promoter can
enhance the signal intensity for our experiments (Figure 2).
To see more details about the construction and result, click the hyperlink below:
lldPRD operon promoter + RBS from E. coli ( lldRO1-plldR-lldRO2 )：BBa_k82000
lldPRD operon promoter + RBS from E. coli ( lldRO1-plldR-lldRO2 )：BBa_k82000