Difference between revisions of "Part:BBa K560000"
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<partinfo>BBa_K560000 short</partinfo>
 
<partinfo>BBa_K560000 short</partinfo>
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== Blue Light Sensing and Reporting System ==
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This part was designed to build the complete blue light sensing and reporting system in a single plasmid. Promoter BBa_J23117 is a constitutive promoter and not a strong one. It will keep a certain concentration of LovTAP in bacteria. When exposure to blue light, the absorption of a photon will leads to conformational rearrangements in LovTAP. The LovTAP can then bind to DNA and repress the transcription of genes following the trpL promoter. Here we use RFP as the reporter.
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[[Image:Whu-Part1-1.png]]
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== Detailed Description of LovTAP ==
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LovTAP is a fusion protein. It consists of a LOV (light-oxygen-voltage) domain of Avena sativa phototropin1 (AsLOV2) and the trpR- DNA binding domain of the transcription factor trp repressor.
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LOV domain is first identified as a new type of light sensor by Swartz et al in the notorious pathogen Brucella abortus. LOV domains belong to the PAS(Per-Arnt-Sim) protein domain superfamily. It has a compact protein module of about 110 amino acids. The LOV domain works through a noncovalently bound flavin cofactor when exposure to blue light. When absorbing a blue photon, the flavin cofactor will form a covalent bond with a conserved cysteine residue in the LOV domain, which results in conformational rearrangements in LovTAP(Fig 2). Flavin-binding LOV domains are fused to a range of “output” domains including bacterial diguanylate cyclases and phosphodiesterases, zincfinger, transcription factors, and histidine, kinases.
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[[Image:Whu-Part2.png]]
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TAP domain is trp-DNA binding domain. Here is the 3D structure of trp repressor(Fig3). Flavin-binding LOV domain changes its conformation when sensing blue light. This change impacts the affinity of the shared helix for the two domains: disrupting the contacts between the shared helix and the LOV domain and enabling the association of the shared helix with the TrpR domain, which establishes DNA-binding affinity and LovTAP can then bind DNA as an homodimer, repressing the transcription of the genes downstream of its binding sites.
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[[Image:Whu-Part3.png]]
  
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LovTAP Photosensor is a chimeric protein. It is built by fusing LOV domain, which senses blue light, to the trpR-DNA binding domain of the transcription factor trp repressor.
 
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Under the presence of blue light, maximum at 450nm, the absorption of a photon leads to conformational rearrangements in LovTAP. The LovTAP can then bind to DNA and repress the transcription of genes following the trpL promoter. Here we use RFP as the reporter.
 
  
  
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===Usage and Biology===
 
  
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<span class='h3bb'>Sequence and Features</span>
 
<span class='h3bb'>Sequence and Features</span>
 
<partinfo>BBa_K560000 SequenceAndFeatures</partinfo>
 
<partinfo>BBa_K560000 SequenceAndFeatures</partinfo>
  
  
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===Functional Parameters===
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===References===
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<partinfo>BBa_K560000 parameters</partinfo>
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''John T.M. Kennis and Sean Crosson. A Bacterial Pathogen Sees the Light. Science 317, 1041(2007).''
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Latest revision as of 16:18, 10 May 2013


Blue Light Sensor+PtrpL+mRFP1

Blue Light Sensing and Reporting System

This part was designed to build the complete blue light sensing and reporting system in a single plasmid. Promoter BBa_J23117 is a constitutive promoter and not a strong one. It will keep a certain concentration of LovTAP in bacteria. When exposure to blue light, the absorption of a photon will leads to conformational rearrangements in LovTAP. The LovTAP can then bind to DNA and repress the transcription of genes following the trpL promoter. Here we use RFP as the reporter.


Whu-Part1-1.png

Detailed Description of LovTAP

LovTAP is a fusion protein. It consists of a LOV (light-oxygen-voltage) domain of Avena sativa phototropin1 (AsLOV2) and the trpR- DNA binding domain of the transcription factor trp repressor. LOV domain is first identified as a new type of light sensor by Swartz et al in the notorious pathogen Brucella abortus. LOV domains belong to the PAS(Per-Arnt-Sim) protein domain superfamily. It has a compact protein module of about 110 amino acids. The LOV domain works through a noncovalently bound flavin cofactor when exposure to blue light. When absorbing a blue photon, the flavin cofactor will form a covalent bond with a conserved cysteine residue in the LOV domain, which results in conformational rearrangements in LovTAP(Fig 2). Flavin-binding LOV domains are fused to a range of “output” domains including bacterial diguanylate cyclases and phosphodiesterases, zincfinger, transcription factors, and histidine, kinases.


Whu-Part2.png

TAP domain is trp-DNA binding domain. Here is the 3D structure of trp repressor(Fig3). Flavin-binding LOV domain changes its conformation when sensing blue light. This change impacts the affinity of the shared helix for the two domains: disrupting the contacts between the shared helix and the LOV domain and enabling the association of the shared helix with the TrpR domain, which establishes DNA-binding affinity and LovTAP can then bind DNA as an homodimer, repressing the transcription of the genes downstream of its binding sites.


Whu-Part3.png



Sequence and Features


Assembly Compatibility:
  • 10
    INCOMPATIBLE WITH RFC[10]
    Illegal SpeI site found at 918
    Illegal SpeI site found at 926
  • 12
    INCOMPATIBLE WITH RFC[12]
    Illegal NheI site found at 7
    Illegal NheI site found at 30
    Illegal SpeI site found at 918
    Illegal SpeI site found at 926
  • 21
    COMPATIBLE WITH RFC[21]
  • 23
    INCOMPATIBLE WITH RFC[23]
    Illegal SpeI site found at 918
    Illegal SpeI site found at 926
  • 25
    INCOMPATIBLE WITH RFC[25]
    Illegal SpeI site found at 918
    Illegal SpeI site found at 926
    Illegal AgeI site found at 1525
    Illegal AgeI site found at 1637
  • 1000
    INCOMPATIBLE WITH RFC[1000]
    Illegal SapI.rc site found at 595


References

John T.M. Kennis and Sean Crosson. A Bacterial Pathogen Sees the Light. Science 317, 1041(2007).