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Molecule
Golden gate Protocol:
After purification of the PCR product, you can digest your part with EcoRI and PstI using the following Protocol:
| Component | Amount (μl) |
|---|---|
| Purified PCR product | 30 |
| EcoRI | 1 |
| PstI | 1 |
| BsaI | 0.5 |
| NEB buffer 4 (10x) | 4 |
| ddH2O | 3.5 |
| Total Volume | 40 |
| Thermocycler programm |
| 1. 37°C, 12 hours |
| 2. 80°C, 20 minutes |
Important note:
We very much advise you to digest the vector for 12 hours and purify the product on a gel. This significantly reduces the risk of religation of you vector. We usually had no colonies on our negative control plate after ligation with T4 ligase and transformation into DH10B cells.
Since most standard iGEM plasmids contain binding sites of the most common two type IIs restriction enzymes (namely BsaI/Eco31I and BsmBI/Esp3I), we propose using BbsI/BpiI. We have tested this enzyme in various reaction conditions with many different reaction additives (such as ATP or DTT). Although ligase buffer worked best with other type IIs restriction enzymes (in those cases, ligase activity probably was the bottleneck), we had best results with G Buffer (Fermantas) plus several additives using BbsI.
Assembling:
For assembling parts that are in Golden Gate standard, we recommend the following protocol:
Ligase Reaction:
With the six TAL BioBricks and the fusion enzyme in your reaction tube you now only need the type two restriction enzyme BsmB1 and a T7 Ligase to put all the parts together.
Transform 5 μl of the GATE assembly product into 50 μl of transformation competent bacteria.
Important note:
Your cells need to be sensitive to the ccdB kill cassette in our TAL expression vectors! Otherwise also bacteria that have taken up plasmids without the six direpeats will form false positive colonies. We used the DH10B E.coli strain.
In case you want to express your TALE in bacteria, you need to induce the promoter of our prokaryotic expression plasmid with IPTG.
For use in a eukaryotic system, such as HEK 239 cells, perform a midiprep and directly transfect the eukaryotic TAL expression plasmid (or its derivatives pTAL-TF, pTALEN etc.) according to your transfection protocol.
We always used this 8:40 hour thermocycler program to obtain best results. However you can also reduce the number of cycles.
Digestion
Gel extraction
PCR Clean-Up
Plasmid Extraction
Cell
Construct the gene of our fusion protein: ssDsbA-FP-HL-Lgt-FL-TAL using splicing by overlap extension. We connected ssDsbA-FP-HL-lgt for one part of this fusion protein and FL-TAL for another. Then connect them together.
Protein
Connected ssDsbA-FP-HL-lgt by splicing by overlap extension. Transform, colony picking plasmid extraction and digestion identification; Sequencing results showed accurate construction.
