McClean: Golden Gate- Making a multi-part plasmid
This protocol describes how to assmble multiple part plasmids via BsaI digestion and T7 Ligase ligation. It is intended to supplement Lee, M. E., DeLoache, W. C., Cervantes, B. & Dueber, J. E. A Highly Characterized Yeast Toolkit for Modular, Multipart Assembly. ACS Synthetic Biology at <http://pubs.acs.org/doi/pdf/10.1021/sb500366v> (2015), as well as its supplementary documents.
- BsaI restriction enzyme.
- T4 Ligase Buffer
- T7 Ligase
- DNA to insert
- Make a 10 μL solution containing:
- 20 femto moles of each plasmid
- 5 units of BsaI, corresponding to 0.5 μL of NEB #R0535S containing 10,000 U/mL
- 1,500 units of T7 Ligase corresponding to 0.5 μL of NEB #M0318S containing 3,000,000 U/mL.
- 1 μL of 10X buffer for T4 Ligase with 10 mM ATP (NEB #B0202S). *Note* This buffer is T4 but the enzyme is T7; this is intentional. T7 has a preservative which prevents T7 from degrading at high temperatures. T4 is very similar to CutSmart buffer, plus it contains ATP.
- Bring to 10 μL with DI water
- Bring the solution to the following temperatures in a thermocycler:
- For 30 cycles
- 42°C for 5 minutes (cutting predominantly occurs at this temperature)
- 16°C for 5 minutes (ligation predominantly occurs at this temperature)
- If the final product DOES NOT HAVE a BsaI dropout segment
- Bring the solution to 42°C for 30 min hours.
- Bring the solution to 60°C for 30 min hours. This is the ideal cutting temp. It is not reached earlier to preserve the integrity of the dissolved ATP (this is my hypothesis, the manual doesn't explain why a non-ideal cutting temp is recommended.)
- Bring the solution to 80°C for 10 minutes. This denatures the cutting and ligating enzymes.
- If the final product DOES HAVE a BsaI dropout segment (OPTION 1)
- Keep the solution at 16°C 30 min
- Store on ice or at 4°C until the solution can be transformed into competent e. coli.
- If the final product DOES HAVE a BsaI dropout segment (OPTION 2)
- Bring this to the higher temperatures that would be appropriate if there was not a BsaI dropout segment.
- After the 80°C step, bring the dATP concentration to 1 mM (assuming the dATP in T4 buffer broke down) by adding 0.1 μL of 100 mM dATP.
- Add 0.5 μL T7 DNA ligase.
- Leave at room temp for 1 hr (or 16°C for perhaps 30 min).
- Proceed with transformation
- For 30 cycles
- Transform this product into competent e. Coli, and select white colonies on Kanamycin.
This protocol is more involved than the one recommended in the Yeast Toolkit paper. It was designed to improve the efficiency of the transformation, and the extra steps are much better than the possibility of redoing the entire experiment. The paper's instructions were designed for simplicity and speed. These instructions are designed to make it work.
- Cameron J. Stewart 13:46, 15 September 2016 (EDT):
Lee, M. E., DeLoache, W. C., Cervantes, B. & Dueber, J. E. A Highly Characterized Yeast Toolkit for Modular, Multipart Assembly. ACS Synthetic Biology at <http://pubs.acs.org/doi/pdf/10.1021/sb500366v> (2015)
or instead, discuss this protocol.