# Gibson assembly
**Gibson assembly** is an isothermal, single-reaction method for joining multiple overlapping DNA fragments into one covalently sealed molecule, using the concerted action of a 5' exonuclease, a [DNA polymerase](https://www.edgepedia.org/dna-polymerase), and a [DNA ligase](https://www.edgepedia.org/dna-ligase). It was described in 2009 by Daniel G. Gibson and colleagues at the J. Craig Venter Institute in *Nature Methods*, and it assembles fragments seamlessly, without restriction sites or added scar sequences[1](https://www.nature.com/articles/nmeth.1318) • [2](https://www.addgene.org/protocols/gibson-assembly/). The method is a major workhorse of synthetic biology and molecular cloning, used for everything from routine plasmid construction to the synthesis of entire bacterial genomes[3](https://www.neb.com/en/applications/cloning-and-synthetic-biology/dna-assembly-and-cloning/gibson-assembly).
| Key fact | Detail |
|---|---|
| Original publication | Gibson, D.G. et al., *Nature Methods* 6, 343–345 (2009); about 10,000 citations and 186,000 accesses[1](https://www.nature.com/articles/nmeth.1318) |
| Enzymes | A 5' exonuclease (T5 exonuclease), a DNA polymerase, and a DNA ligase in one buffer; an optional single-stranded binding protein improves accuracy and efficiency[1](https://www.nature.com/articles/nmeth.1318) • [2](https://www.addgene.org/protocols/gibson-assembly/) |
| Reaction conditions | Single-tube isothermal reaction; the NEB Gibson Assembly Master Mix runs at 50 degrees C[3](https://www.neb.com/en/applications/cloning-and-synthetic-biology/dna-assembly-and-cloning/gibson-assembly) |
| Overlap requirement | Adjacent fragments share terminal homology; the GeneArt Gibson Assembly HiFi protocol specifies 20–40 bp overlaps, with longer overlaps improving higher-order assembly[4](https://www.thermofisher.com/TFS-Assets/LSG/manuals/MAN0019062_GeneArtGibsonHiFi_UG.pdf) |
| Landmark uses | 144 kbp fragments of the *Mycoplasma genitalium* genome; the 16.3 kb mouse mitochondrial genome from 600 overlapping 60-mers; the 1.1 Mbp *Mycoplasma mycoides* genome with yeast assembly[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC4853029/) • [6](https://www.neb.com/tools-and-resources/feature-articles/gibson-assembly-building-a-synthetic-biology-toolset) • [3](https://www.neb.com/en/applications/cloning-and-synthetic-biology/dna-assembly-and-cloning/gibson-assembly) |
| Practical limits | Efficiency drops sharply above about five fragments in one reaction, and the exonuclease can destroy fragments shorter than 250 bp before they anneal[2](https://www.addgene.org/protocols/gibson-assembly/) • [7](https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/overlap-extension-polymerase-chain-reaction) |
## Mechanism
The reaction coordinates three enzymatic activities in one tube[1](https://www.nature.com/articles/nmeth.1318):
1. A 5' exonuclease chews back the 5' ends of each linear fragment, exposing single-stranded 3' overhangs.
2. Complementary overhangs on adjacent fragments anneal to each other.
3. A DNA polymerase fills in the gaps on the annealed single-stranded regions.
4. A DNA ligase seals the remaining nicks, producing a fully ligated double-stranded DNA molecule[1](https://www.nature.com/articles/nmeth.1318) • [8](https://static.igem.org/mediawiki/2014/b/b9/Bielefeld-CeBiTec_2014-08-28_Gibson_Assembly.pdf).
Because the overlaps are generated by exonuclease chew-back rather than by restriction enzymes, almost any two fragments can be joined regardless of their end sequence, and no scar is introduced between joined fragments[2](https://www.addgene.org/protocols/gibson-assembly/). The overlapping sequence of adjoining fragments is much longer than the defined overhangs used in [Golden Gate](https://www.edgepedia.org/golden-gate) assembly, which NEB states results in a higher percentage of correct assemblies[3](https://www.neb.com/en/applications/cloning-and-synthetic-biology/dna-assembly-and-cloning/gibson-assembly).
## Design and workflow
Fragments are prepared so that each end carries a region homologous to the adjacent fragment, typically by PCR with primers whose 5' ends add the overlap, or by direct DNA synthesis[4](https://www.thermofisher.com/TFS-Assets/LSG/manuals/MAN0019062_GeneArtGibsonHiFi_UG.pdf). The GeneArt HiFi protocol specifies 20–40 bp of terminal homology between each fragment, including the vector, and notes that longer overlaps can raise efficiency in higher-order assemblies[4](https://www.thermofisher.com/TFS-Assets/LSG/manuals/MAN0019062_GeneArtGibsonHiFi_UG.pdf). Reviews of homologous-overlap assembly describe the method as assembling fragments with more than 15 bp homologous overlaps in one-pot isothermal conditions[9](https://pmc.ncbi.nlm.nih.gov/articles/PMC8299547/).
The assembled product is then transformed into a host such as *E. coli*, where it replicates as a plasmid. Commercial kits combine the assembly master mix with competent cells so that fragment assembly and transformation take under 2 hours[10](https://www.neb.com/en/-/media/nebus/files/catalogs/neb_usacatalog_rgb_150dpi.pdf). Software tools such as [SnapGene](https://www.edgepedia.org/snapgene), Benchling, and the open-source Python pydna package support design of Gibson assembly experiments[4](https://www.thermofisher.com/TFS-Assets/LSG/manuals/MAN0019062_GeneArtGibsonHiFi_UG.pdf).
## Landmark applications
Gibson assembly was first developed while cloning the synthetic *Mycoplasma genitalium* genome[11](https://doi.org/10.1146/annurev-biochem-013118-110704). It was used to construct 144 kbp fragments of that genome, which were in turn assembled in yeast into constructions containing the entire bacterial genome[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC4853029/); the complete *M. genitalium* genome is 583 kb[12](https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2014.00060/pdf).
The method also assembled the 16.3 kb mouse mitochondrial genome directly from 600 overlapping 60-mer oligonucleotides[6](https://www.neb.com/tools-and-resources/feature-articles/gibson-assembly-building-a-synthetic-biology-toolset) • [12](https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2014.00060/pdf). Working alongside yeast-based in vivo assembly, Gibson assembly enabled synthesis of the 1.1 Mbp *Mycoplasma mycoides* genome; this synthetic genome was then placed into a *M. capricolum* recipient cell, producing *M. mycoides* cells capable of self-replication[3](https://www.neb.com/en/applications/cloning-and-synthetic-biology/dna-assembly-and-cloning/gibson-assembly). Beyond genome projects, the method has been applied to pathway construction in production hosts; optimizing the [Impossible Foods](https://www.edgepedia.org/impossible-foods) strain that makes soy leghemoglobin involved DNA synthesis, Gibson Assembly, and genetic part libraries[13](https://www.nature.com/articles/s41467-020-20122-2).
## Limitations and comparison with other methods
The number of parts assembled in a single step must be limited to maintain high efficiency, so large final products may require multiple intermediate assembly steps[11](https://doi.org/10.1146/annurev-biochem-013118-110704). Some labs have observed a sharp decrease in success rate when assembling more than five fragments at a time[2](https://www.addgene.org/protocols/gibson-assembly/). A specific biochemical limitation is that the T5 exonuclease can completely chew through short DNA fragments, under 250 base pairs, before they can anneal with adjacent fragments and prime the polymerase[7](https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/overlap-extension-polymerase-chain-reaction). Reviews also note that the method requires a delicate balance of enzyme concentrations, DNA fragment concentrations, reaction times, and temperatures, which makes standardization for automation difficult[14](https://pmc.ncbi.nlm.nih.gov/articles/PMC12360497/).
Compared with traditional restriction-enzyme cloning, Gibson assembly needs no specific restriction sites, leaves no scar, requires fewer steps, and can combine many fragments at once[2](https://www.addgene.org/protocols/gibson-assembly/). Compared with Golden Gate assembly, which uses type IIS restriction enzymes and ligase to produce precisely defined short overhangs, Gibson relies on longer homologous overlaps and is sequence-independent at the junctions; Golden Gate is often preferred for highly standardized, modular assemblies, while Gibson suits one-off joins of fragments with arbitrary ends[15](https://pmc.ncbi.nlm.nih.gov/articles/PMC9680027/). A 2013 survey found Gibson assembly was one of the most commonly used assembly methods[16](https://www.sevierlab.org/_files/ugd/5599cf_646e4e2a972644e48f151eb6a7d4414a.pdf).
## Commercial variants
New England Biolabs sells the Gibson Assembly Master Mix (NEB #E2611) and Cloning Kit (NEB #E5510S), licensed from TelesisBio, and the related NEBuilder HiFi DNA Assembly mix, which uses a proprietary high-fidelity polymerase and can correct 5' and 3' end mismatches[3](https://www.neb.com/en/applications/cloning-and-synthetic-biology/dna-assembly-and-cloning/gibson-assembly) • [17](https://www.neb.com/en-us/applications/cloning-and-synthetic-biology/dna-assembly-and-cloning/nebuilder-hifi-dna-assembly?redi=RegulatedMarkets). Thermo Fisher sells GeneArt Gibson Assembly HiFi kits[4](https://www.thermofisher.com/TFS-Assets/LSG/manuals/MAN0019062_GeneArtGibsonHiFi_UG.pdf). Related restriction-free overlapping-sequence methods include In-Fusion, CPEC, PIPE, SLIC, and T5 exonuclease-dependent assembly (TEDA)[18](https://arxiv.org/abs/2505.03681).
## References
1. [Gibson, D.G. et al. (2009). Enzymatic assembly of DNA molecules up to several hundred kilobases. Nature Methods 6, 343–345.](https://www.nature.com/articles/nmeth.1318)
2. [Addgene: Gibson Assembly Protocol](https://www.addgene.org/protocols/gibson-assembly/)
3. [New England Biolabs: Gibson Assembly application overview](https://www.neb.com/en/applications/cloning-and-synthetic-biology/dna-assembly-and-cloning/gibson-assembly)
4. [GeneArt Gibson Assembly HiFi Cloning Kits User Guide, Thermo Fisher](https://www.thermofisher.com/TFS-Assets/LSG/manuals/MAN0019062_GeneArtGibsonHiFi_UG.pdf)
5. [Overview of post Cohen-Boyer methods for single segment cloning and multisegment DNA assembly, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC4853029/)
6. [NEB feature article: Gibson Assembly, building a synthetic biology toolset](https://www.neb.com/tools-and-resources/feature-articles/gibson-assembly-building-a-synthetic-biology-toolset)
7. [Overlap Extension Polymerase Chain Reaction overview, ScienceDirect Topics](https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/overlap-extension-polymerase-chain-reaction)
8. [iGEM Bielefeld 2014: Gibson Assembly protocol document](https://static.igem.org/mediawiki/2014/b/b9/Bielefeld-CeBiTec_2014-08-28_Gibson_Assembly.pdf)
9. [The evolving art of creating genetic diversity, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC8299547/)
10. [NEB DNA Assembly & Cloning catalog](https://www.neb.com/en/-/media/nebus/files/catalogs/neb_usacatalog_rgb_150dpi.pdf)
11. [Zhang, Mitchell, Bader & Boeke (2020). Synthetic Genomes. Annual Review of Biochemistry 89, 77–101.](https://doi.org/10.1146/annurev-biochem-013118-110704)
12. [Developments in the tools and methodologies of synthetic biology, Frontiers in Bioengineering and Biotechnology](https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2014.00060/pdf)
13. [Synthetic biology 2020–2030: six commercially-available products, Nature Communications](https://www.nature.com/articles/s41467-020-20122-2)
14. [Scaling DNA Engineering, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC12360497/)
15. [A User's Guide to Golden Gate Cloning Methods and Standards, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC9680027/)
16. [Common Cloning Techniques, Sevier Lab chapter](https://www.sevierlab.org/_files/ugd/5599cf_646e4e2a972644e48f151eb6a7d4414a.pdf)
17. [NEBuilder HiFi DNA Assembly, New England Biolabs](https://www.neb.com/en-us/applications/cloning-and-synthetic-biology/dna-assembly-and-cloning/nebuilder-hifi-dna-assembly?redi=RegulatedMarkets)
18. [A review of DNA restriction-free overlapping sequence cloning techniques for synthetic biology, arXiv](https://arxiv.org/abs/2505.03681)
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*Topic: Encyclopedia › Life and health › Applied biology and nonhuman health › Biotechnology and biological production › Bioprocess engineering and biomanufacturing › Recombinant proteins and enzyme technology › Restriction enzymes and cloning tools*
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