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First-Stage Plasmid (Transcriptional Unit) Assembly

Once you have all your desired part plasmids built you can assemble them into Transcriptional units (TU). Typically these plasmids will be assembled with part plasmids for promoter + RBS, coding sequence, terminator, and TU specific connectors; variations on this basic strategy are easily managed though as long as the requisite overhangs are present (Described here).

Assembly reaction

Total volume will be 20 μL; you will need 10 fmol of each part plasmid for this assembly. Typically the pBTK095 part plasmid (ColE1 origin, sfGFP dropout) is used as the backbone for this assembly. If toxicity issues may be a factor, lower copy number vectors can easily be used in its place.

  • 10 fmol of each part plasmid
  • 2 μL of 10 T4 DNA ligase buffer (Promega)
  • 1 μL of BsaI-HFv2 ( DO NOT use BsaI-HF*)
  • 1 μL of T4 DNA ligase (Promega)
  • x μL water up to 20 μL total.

*BsaI-HF is optimized for different buffer conditions and doesn't work well

** Promega T4 Ligase buffer has been shown to offer the highest activity for BsaI enzyme. Other T4 ligase enzymes will work, but Promega enzyme with Promega buffer is highest efficiency.


Mix samples well by pipetting, then run the reaction on the thermocycler under the following conditions:

Step Temperature Time
1 37C 1.5 min
2 16C 3 min
Cycles 1-2: Repeat 25x  
3 37C 5 min
4 80C 10 min

  • Transform 2 μL assembly reaction and plate on appropriate antibiotic

Due to the nature of attempting to assemble a high number of plasmids in one reaction there are often issues that arise: Check out troubleshooting tips here


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-- Main.KateElston - 29 Jan 2018

 Barrick Lab  >  BroadHostRangeToolkit  >  ProtocolsBTKAssembleSingleTUPlasmid

Topic revision: r9 - 07 Jun 2018 - 19:42:39 - Main.DennisMishler
 
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