Multi-fragment Gibson Assembly: An Implementation Checklist
This implementation checklist for multi-fragment Gibson assembly is a Gibson-only overlap-to-bench procedure. Write fragment order, prove adjacent ends are identical, match the 2–3 versus 4–6 fragment bands, then verify junctions. Colony count is not done. Restriction-ligation has its own checklist. Golden Gate is a different chemistry and is not a ZettaGene simulation claim.
Outcome, Prerequisites, and Boundary
When the checklist is implemented you have a written fragment order, identical overlaps on every junction, and a planned junction check. You already have sequences and authority to freeze the map. You do not yet need a new brand.
Addgene's Gibson protocol states the design rule this page turns into a gate: adjacent segments must share identical terminal sequence. Buying master mix is not that gate. The restriction-cloning checklist owns digest-and-ligate. This page does not rewrite it, and it does not switch to Golden Gate when a six-way assembly fails.
After the overlap plan exists, ZettaGene can simulate Gibson assembly. Simulation is not assembly success.
Run the Overlap Plan in Order
- Name fragment order — backbone and each insert, left to right as they will sit in the product. Checkpoint: a second person can read the order without asking the designer.
- Write identical terminal overlaps on every junction. Addgene: the identical sequence can be added on PCR primers. Checkpoint: each overlap matches the neighbor letter for letter, not "about 20 bp."
- Match the fragment-count band. NEB E5510 uses 0.02–0.5 pmol total DNA and 15 minutes at 50 °C for 2–3 fragments, and 0.2–1.0 pmol and 60 minutes for 4–6 fragments. The companion tips page gives Gibson overlaps of 15–25 nt (2–3 fragments) and 20–80 nt (4–6 fragments). Quote the Gibson row, not the HiFi row. Checkpoint: count, overlap length, and time sit on one card.
- Set insert-to-vector amounts from that same card. NEB: 2–3-fold molar excess of each insert for 2–3 fragment assemblies; 1:1 for 4–6 fragment assemblies; keep unpurified PCR at or below 20% of the reaction. Checkpoint: the calculation is written before the tube is mixed.
- Incubate at 50 °C for the band you chose, then transform. Treat verification and rollback as the next sections, not as optional extras.
ZettaGene is named only after those overlaps are written. It does not replace step 2.
Stage, Output, and Completion Criteria
A manager can mark progress without opening the kit insert.
| Stage | Output | Done when |
|---|---|---|
| Fragment order | Left-to-right list with owners | A second person can read the product without asking |
| Overlap identity | Letter-identical ends on every junction | Each overlap matches the neighbor, not an estimate |
| Amounts and time | 2–3 versus 4–6 band written | pmol, minutes, and overlap length sit on one card |
| Incubation | 50 °C reaction stored for transformation | Time matches the fragment-count band |
| Junction check | Sequence or junction assay versus the plan | Accepted clone matches the written ends |
| Rollback | Frozen last signed overlap map | Stale oligos and leftover template are stopped |
Buying master mix is not a phase.
Expected Result and Verification
Addgene describes the product as a fully ligated double-stranded DNA molecule. The definition of done on this checklist is narrower: the accepted clone matches the written overlap plan at the junctions.
Run two tests. First, a junction-spanning assay or Sanger reads across every designed join. Second, when those junctions are decision-critical, sequence the regions that decide whether the construct is the expected product. Colony number is a fail if it is the only evidence. A band of the expected size is not full proof.
Failure Paths and Rollback
NEB and Addgene both note that efficiency falls as fragment number rises. Addgene: some labs see a sharp drop beyond about five fragments. That is a reason to split a six-way plan into sequential three-way assemblies. It is not a reason to invent Golden Gate on this page.
- Overlap shorter than the cited band, or a Tm below the 48 °C tip on the Gibson row — recalculate; do not lengthen blindly.
- Too many fragments in one tube — freeze the last signed map and split the assembly.
- Leftover circular template — treat background colonies as a template problem, not as success.
- An order that went out from an unsigned overlap — stop the dependent oligos and assign one reconciler.
Rollback is a freeze-and-split rule. It is not a promise the kit will rescue a bad overlap.
Frequently Asked Questions
What has to be written before a multi-fragment Gibson reaction?
Fragment order and identical terminal overlaps on every junction. A kit box is not that record.
How do we know a Gibson assembly actually worked?
Junction sequence or a junction-spanning assay matches the written ends. Colony count is not that test.
Why did a six-fragment Gibson fail when a three-fragment plan worked?
Efficiency is known to fall as fragment number rises. Split the plan rather than inventing a new chemistry on this page.
Is this the same checklist as restriction cloning or Golden Gate?
No. Restriction-ligation has its own checklist. Golden Gate is out of scope and is not a ZettaGene simulation claim.
Related Articles