Dandekar & Chandler: PCR "sewing"
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PCR "sewing" of two fragments with overlapping regions of homology
- "Sewing" is a bastardization of "SOE" which stands for Splicing by overlap/overhang extension
- This protocol has not yet failed Nicole even once
- This protocol is lifted from iGEM
- Watson gives this protocol two paws up
iGEM PCR Sewing Protocol
Reaction Set Up
You will need the following ingredients for the Sewing PCR mix:
If you are going to be cloning with this fragment (and you know you are) use Phusion for best results!
- Fragment #1 5.0ul
- Fragment #2 5.0ul
- dNTPs 1.0ul
- DMSO (optional) 1.0ul
- 5x Phusion buffer 10.0ul
- ddH2O 27.5ul (or enough to 50ul total)
- Phusion polymerase 0.5ul
Pro Tip - If you are doing multiple PCR’s, prepare a Master Mix by adding the common ingredients for all reactions to one pot. Add the polymerase LAST.
Cycling Protocol
The PCR sewing reaction takes place in two parts
In the first part, you will run the usual PCR cycle for only 5 cycles in order to let the fragments prime each other and synthesize a small amount of full length DNA product
Part I
Step 1 (Denaturation): 98˚C 30 sec (for high GC, we use 3 min; the point here is get single strands and to linearize so that the overlapping regions can find each other)
Step 2 (Denaturation loop): 98˚C 15 sec
Step 3 (Annealing): 50˚C – 60˚C 25 sec
Step 4 (Elongation): 72˚C 30 sec/kb
-- repeat steps 2-4 for a total of 5 cycles --
Step 5 (Final Elongation): 72˚C 5 min
Step 6 (Storage): 4˚C forever
Part II
After the first 5 cycles are over, add 1.0ul of 10uM end primers to each tube
Also add 0.5ul of Phusion polymerase
Run the PCR for an additional 20-25 cycles, as usual
Step 1 (Denaturation): 98˚C 30 sec
Step 2 (Denaturation loop): 98˚C 15 sec
Step 3 (Annealing): 50˚C – 60˚C 25 sec
Step 4 (Elongation): 72˚C 30 sec/kb
Step 5 (Final Elongation): 72˚C 5 min
Step 6 (Storage): 4˚C forever
