Difference between revisions of "Part:BBa K2904030"

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===The construction of this part===
 
===The construction of this part===
  
After constructing modular kinetic riboswitches, we then want to demonstrate that our guideline can also apply to the thermodynamic riboswitch. So we designed a modular Four U riboswitch containing the original Four U riboswitch, Stabilizer and Tuner A. Using docking matrix, we selected the first 132bp of RFP as Stabilizer because RFP can express under the control of Four U.  
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After successfully constructing modular kinetic riboswitches, we then want to demonstrate that our guideline can also apply to the thermodynamic riboswitch, which can response to temperature based on conformation changes. Therefore, we selected a thermodynamic switch named Four U that performed well and designed a modular Four U riboswitch containing the original switch, Stabilizer and Tuner A. Using docking matrix, we selected the first 132bp of RFP as Stabilizer because RFP can express under the control of Four U.
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==<strong>Result</strong>==
 
==<strong>Result</strong>==
To validate this new thermodynamic switch, we engineered a device including the tetracycline promoter, the modular Four U riboswitch and sfGFP.
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To validate this new thermodynamic switch, we engineered a device including a constitutive promoter(BBa_J23119), the modular Four U riboswitch and sfGFP. After construction, the circuit was transformed into DH5αZ1. Given that the temperature threshold of Four U is 37℃, we set the culture temperature to 28℃, 37℃ and 42℃ in liquid LB medium respectively. We can observe a noticeable difference when cultured for 30 hours. Though centrifugation, the recombination strain at 37°C and 42°C shows green while the strain at 28°C shows no fluorescence.
We did three kinds of experiments to help us confirm the function of modular Btub riboswitch containing Tuner E.
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[[Image:T--OUC-China--dpzz.png|center|thumb|350px|'''Figure1:  The results of liquid test show the working effect of modular Four U in different temperature.'''  ]]
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===The result by confocal microscopy===
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The above qualitative experiments are not enough to verify the effect of modular Four U, so we tested the fluorescence intensity by microplate reader to measure the expression level of the reporter protein legulated by FourU element as temperature-controlled switch. We still set three culture temperatures: 28°C, 30°C and 37°C. After overnight culture, we choose 5 time points (8h, 24h, 30h, 36h, 48h) to test fluorescence intensity of sfGFP protein. The results demonstrate that moduar FourU element is a useful thermodynamic riboswitch and works very well!
 
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[[Image:T--OUC-China--030microplate.jpg|center|thumb|400px|'''Figure2: The results of microplate reader show the working effect of modular Four U element in different temperature.'''  ]]
 
<p>
 
<p>
First, we selected sfGFP as the output of our system. It was under control of the tetracycline promoter, which was induced by aTc. For the sake of functional test, other 2 circuits are set, Btub-sfGFP and Btub-Stabilizer-sfGFP, which also were under control of the same promoter. By Confocal Microscopy Leica TCS SP8, it’s obvious that no fluorescence could be observed when the Btub riboswitch had sfGFP introduced directly. By comparison with Btub fusion, the modular Btub riboswitch demonstrates a greater induction difference since Tuner has the ability to improve the function of riboswitch. 
 
 
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<br>
</p>
 
 
===The result by microplate reader===
 
 
<p>
 
The qualitative experiment is not enough to analyze the modular Btub riboswitch. So we tested our system by microplate reader, which is used to reflect the intensity of sfGFP changing over time. The following chart shows the dynamic curve measured every two hours. It can prove that the modular Btub riboswitch can restore the structure of riboswitch and control the downstream gene expression during the whole cultivation period.
 
 
<br>
 
<br>
</p>
 
[[Image:T--OUC-China--081microplateg.jpg|center|thumb|400px|'''Figure1: The results of modular Btub riboswitch containing Tuner E by microplate reader.'''  ]]
 
  
 
<!-- Add more about the biology of this part here
 
<!-- Add more about the biology of this part here

Latest revision as of 11:14, 21 October 2019


Modular Four U riboswitch

Design

Background of 2019 OUC-China's project——RiboLego

Due to context-dependent performance and limited dynamic range, the widespread application of riboswitches is currently restricted. By replacing its original ORF with a new one, the structure of an aptamer domain can be subtly disrupted, resulting in a loss of ligand response. So riboswitch is still not be considered as a ‘plug and play' device. To tackle these problems, our project focuses on a standardized design principle to be used for modular and tunable riboswitch. The modular riboswitch we defined consists of the original riboswitch, Stabilizer and Tuner. Stabilizer can protect the structure of riboswitch from damage while Tuner can reduce the expression probability of fusion protein and make improvement of riboswitch function.

The construction of this part

After successfully constructing modular kinetic riboswitches, we then want to demonstrate that our guideline can also apply to the thermodynamic riboswitch, which can response to temperature based on conformation changes. Therefore, we selected a thermodynamic switch named Four U that performed well and designed a modular Four U riboswitch containing the original switch, Stabilizer and Tuner A. Using docking matrix, we selected the first 132bp of RFP as Stabilizer because RFP can express under the control of Four U.

Result

To validate this new thermodynamic switch, we engineered a device including a constitutive promoter(BBa_J23119), the modular Four U riboswitch and sfGFP. After construction, the circuit was transformed into DH5αZ1. Given that the temperature threshold of Four U is 37℃, we set the culture temperature to 28℃, 37℃ and 42℃ in liquid LB medium respectively. We can observe a noticeable difference when cultured for 30 hours. Though centrifugation, the recombination strain at 37°C and 42°C shows green while the strain at 28°C shows no fluorescence.

Figure1: The results of liquid test show the working effect of modular Four U in different temperature.


The above qualitative experiments are not enough to verify the effect of modular Four U, so we tested the fluorescence intensity by microplate reader to measure the expression level of the reporter protein legulated by FourU element as temperature-controlled switch. We still set three culture temperatures: 28°C, 30°C and 37°C. After overnight culture, we choose 5 time points (8h, 24h, 30h, 36h, 48h) to test fluorescence intensity of sfGFP protein. The results demonstrate that moduar FourU element is a useful thermodynamic riboswitch and works very well!

Figure2: The results of microplate reader show the working effect of modular Four U element in different temperature.



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]