Part:BBa_K1467205

AvrBS3 TAL Effector - Induces BS3

TAL (transcription activator-like) Effector that induces the BS3 promoter. The part is compatible with the GoldenGate MoClo Assembly Standard due to the fact that it is free from internal BsaI and BpiI recognition sequences.

TAL (transcription activator-like) Effectors are proteins that are naturally excreted by the Xanthamonas type III secretion system and bind to specific recognition sequences on host DNA, activating a plant cell response to infection.

TALEs are now engineered for use in research allowing various, specific promoters to be artificially switched on in the presence of the TALE, activating transcription of the gene of interest.

This part was used by iGEM14_NRP-UEA-Norwich in The Green Canary Project and functioned in a multi-gene construct to induce activity of the BS3 promoter. In constructs where the TALE is present in conjunction with the BS3 promoter, the promoter is activated and drives transcription of the reporter. The advantage of using TALEs is that we do not need to use real pathogens to induce activation of the promoter BS3, allowing safe and easy testing of the experimental system in the laboratory. The presence of the AvrBS3 TALE effector represents infection of the plant by a pathogen. BS3 is induced by this, meaning that it is a useful tool for engineering a response to pathogen infection for our proof of concept model.

Figure 1: A Nicotiana benthamiana leaf under UV light following infiltration (red circles) with Agrobacterium tumefaciens carrying plasmids encoding BS3_GFP_ocs (B) and BS3_GFP_ocs + 35s_AvrBS3_nos (A) respectively.

There is GFP expression in the area infiltrated with the multigene construct containing both the BS3 promoter and the TALE AvrBS3, showing that the promoter is active (A). In the area in which the infiltrated agrobacterium was just carrying the transcriptional unit encoding the promoter, GFP and terminator, there is no expression of GFP as the BS3 promoter is not active (B). This shows the function of AvrBS3 in activating the inducible BS3 promoter.

Sequence and Features

Assembly Compatibility:

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

  Illegal NheI site found at 1097
  Illegal NheI site found at 3050
  
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal BglII site found at 3209
  Illegal BamHI site found at 4
  Illegal BamHI site found at 2817
  Illegal BamHI site found at 3412
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal AgeI site found at 770
  
• 1000
  COMPATIBLE WITH RFC[1000]