Difference between revisions of "Part:BBa K4169028"
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===Usage and Biology===
 
===Usage and Biology===
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<p>This is a promoter sequence that initiates transcription of subsequent gene sequences under aerobic conditions and is part of the operon structure of cydAB. Under anaerobic conditions, the Fnr protein will bind to a part of the promoter sequence, impeding RNA polymerase binding, playing a competitive role, and the downstream gene sequence cannot be transcribed. However, under microoxygen conditions, AcrA protein binds to this promoter and recruits RNA polymerase to bind to the promoter, thereby normally initiating downstream transcription. Under aerobic conditions, RNA polymerase normally binds to the promoter. So this is a promoter sequence that can be transcribed normally under aerobic conditions.
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<p>
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This is a promoter sequence that initiates transcription of subsequent gene sequences under aerobic conditions and is part of the operon structure of cydAB. Under anaerobic conditions, the Fnr protein will bind to a part of the promoter sequence, impeding RNA polymerase binding, playing a competitive role, and the downstream gene sequence cannot be transcribed. However, under microoxygen conditions, AcrA protein binds to this promoter and recruits RNA polymerase to bind to the promoter, thereby normally initiating downstream transcription. Under aerobic conditions, RNA polymerase normally binds to the promoter. So this is a promoter sequence that can be transcribed normally under aerobic conditions.
 
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===Functional Parameters===
 
===Functional Parameters===
 
<partinfo>BBa_K4169028 parameters</partinfo>
 
<partinfo>BBa_K4169028 parameters</partinfo>
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<partinfo>BBa_K3733043 short</partinfo>
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Use a constitutive promoter (BBa_J23110), RNA thermometer (BBa_K3733011), strong RBS (BBa_B0034), toxin HepT (BBa_K3733010), and a strong transcriptional terminator Lambda t1 transcriptional terminator (BBa_K864601). Will express the HepT toxin below 28 &#8451; to commit suicide.
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===Usage and Biology===
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<p>
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This composite part is one of temperature-based suicide schemes for the engineered bacteria functioning in mammal intestine. It was designed to lead bacteria to commit suicide as they are leaked into the environment (at low temperatures) but do not affect the growth of engineered bacteria in intestine (at high temperatures).
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</p>
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===Functional Parameters===
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<p>
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To verify the function of this composite part, we transferred it into <i>E.coli</i> DH5α. Meanwhile, we also transformed blank plasmid (only with <i>ori</i> and <i>cmR</i>) into DH5α as control group. We incubated engineered bacteria at 37 ℃ and 28 ℃, taking the bacteria with blank plasmid as control. As the <b>Figure 1</b> shows, medium of experimental group shaked at 28 ℃ is more limpid than ones shaked at 37 ℃; however, in the control group, the medium shaked at 28 ℃ is almost as turbid as ones shaked at 37 ℃.
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<center><img src="https://static.igem.org/mediawiki/parts/7/79/T--HZAU-China-HepT-comp-1.png" style="width:793px;height:360px"></center>
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<center><b>Figure 1. A.</b> The comparison photo of the experimental group (toxin system) and control group incubated at both 37 ℃ and 28 ℃ for 12 hours. Sch.1 means the experimental group (toxin system). Control means the control group. <b>B.</b> The specific OD<sub>600</sub> data of the experimental group and control group. </center>
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We also plotted the quantitative growth curves at 28 ℃ in this suicide scheme. We got OD<sub>600</sub> data changing over time by culturing our engineered bacteria and control bacteria in an automatic microplate reader for 12 hours. Compared with controls, the growth of our engineered bacteria was inhibited obviously(<b>Figure 2</b>).
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<center><img src="https://static.igem.org/mediawiki/parts/1/19/T--HZAU-China-HepT-comp-2.png" style="width:600px;height:360px"></center>
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<center><b>Figure 2.</b> The quantitative growth curves in 12 hours at 28 ℃. </center>
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To further verify the temperature sensibility of this composite part, we reput bacteria cultured at 28 ℃ into an oribital shaker at 37 ℃ overnight. Compared with themselves, the medium becomes turbid observably at 37 ℃, which means this part could make engineered bacteria kill themselves at 28 ℃ and let them survive at 37 ℃, working as expected(<b>Figure 3</b>).
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<center><img src="https://static.igem.org/mediawiki/parts/c/c4/T--HZAU-China-HepT-comp-3.png" style="width:500px;height:360px"></center>
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<center><b>Figure 3.</b> The comparison photo of the bacteria transferred from 28 ℃ to 37 ℃ and the bacteria cultured at 37 ℃ all along. </center>
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===Sequence and Features===
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<span class='h3bb'>Sequence and Features</span>
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<partinfo>BBa_K3733043 SequenceAndFeatures</partinfo>
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===Functional Parameters===
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<partinfo>BBa_K3733043 parameters</partinfo>
 
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Revision as of 03:18, 11 October 2022


Pcyd: A promoter open in aerobic conditions

This is an aerobically initiated promoter that initiates transcription of subsequent sequences under microaerobic and aerobic conditions. The mechanism is based on the fact that Fnr takes over the promoter sequence under anaerobic conditions, competes with RNA polymerase for binding sites, and thus prevents the transcription of subsequent sequences. However, under microaerobic and aerobic conditions, Fnr protein does not bind to the sequence, and thus can continue the subsequent transcription.

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]



HepT suicide system working at low temperatures

Use a constitutive promoter (BBa_J23110), RNA thermometer (BBa_K3733011), strong RBS (BBa_B0034), toxin HepT (BBa_K3733010), and a strong transcriptional terminator Lambda t1 transcriptional terminator (BBa_K864601). Will express the HepT toxin below 28 ℃ to commit suicide.

Usage and Biology

This composite part is one of temperature-based suicide schemes for the engineered bacteria functioning in mammal intestine. It was designed to lead bacteria to commit suicide as they are leaked into the environment (at low temperatures) but do not affect the growth of engineered bacteria in intestine (at high temperatures).

Functional Parameters

To verify the function of this composite part, we transferred it into E.coli DH5α. Meanwhile, we also transformed blank plasmid (only with ori and cmR) into DH5α as control group. We incubated engineered bacteria at 37 ℃ and 28 ℃, taking the bacteria with blank plasmid as control. As the Figure 1 shows, medium of experimental group shaked at 28 ℃ is more limpid than ones shaked at 37 ℃; however, in the control group, the medium shaked at 28 ℃ is almost as turbid as ones shaked at 37 ℃.


无标题文档

Figure 1. A. The comparison photo of the experimental group (toxin system) and control group incubated at both 37 ℃ and 28 ℃ for 12 hours. Sch.1 means the experimental group (toxin system). Control means the control group. B. The specific OD600 data of the experimental group and control group.

We also plotted the quantitative growth curves at 28 ℃ in this suicide scheme. We got OD600 data changing over time by culturing our engineered bacteria and control bacteria in an automatic microplate reader for 12 hours. Compared with controls, the growth of our engineered bacteria was inhibited obviously(Figure 2).

无标题文档

Figure 2. The quantitative growth curves in 12 hours at 28 ℃.

To further verify the temperature sensibility of this composite part, we reput bacteria cultured at 28 ℃ into an oribital shaker at 37 ℃ overnight. Compared with themselves, the medium becomes turbid observably at 37 ℃, which means this part could make engineered bacteria kill themselves at 28 ℃ and let them survive at 37 ℃, working as expected(Figure 3).

无标题文档

Figure 3. The comparison photo of the bacteria transferred from 28 ℃ to 37 ℃ and the bacteria cultured at 37 ℃ all along.

Sequence and Features

Sequence and Features


Assembly Compatibility:
  • 10
    COMPATIBLE WITH RFC[10]
  • 12
    INCOMPATIBLE WITH RFC[12]
    Illegal NheI site found at 7
    Illegal NheI site found at 30
  • 21
    COMPATIBLE WITH RFC[21]
  • 23
    COMPATIBLE WITH RFC[23]
  • 25
    COMPATIBLE WITH RFC[25]
  • 1000
    INCOMPATIBLE WITH RFC[1000]
    Illegal SapI site found at 82