Gene Assembly Oligo Pool - Gibson, Golden Gate & PCA

Use this gene assembly oligo pool guide when you need to turn one or more gene sequences into order-ready assembly fragments. Start with the main oligo pool guide first if you need the broader design, synthesis, QC, or vendor-decision sequence. It covers fragment length, overlap strategy, amplification planning, and verification stepsfor Gibson, Golden Gate, and PCA assembly before you place the synthesis order. After the fragment architecture is fixed, use the ordering checklist and pool vendor comparison to confirm length tier, QC scope, and file requirements.

Complex DNA double helix assembled block-by-block from glowing synthetic oligo fragments

De novo synthesis of a custom genetic circuit using overlapping oligo pool fragments.

Key Facts

  • A 3 kb gene needs only 19-34 oligos depending on length (200 bp or 120 bp)
  • Multiple genes can be assembled from a single pool using gene-specific amplification primers
  • Overlap design: 20-40 bp for Gibson/PCA (Tm 62-70°C), 4 bp overhangs for Golden Gate
  • Error correction (enzymatic or selection-based) compensates for array synthesis error rates

Which Assembly Method Fits Your Construct?

MethodOverlapsMax FragmentsBest ForError Handling
Gibson Assembly20-40 bp, Tm 62-70°C5-10 fragmentsStandard gene assemblyPost-assembly sequencing
Golden Gate4 bp overhangs (BsaI)10-30+ fragmentsModular, scarless assemblySequence verification
PCA (Polymerase Cycling)20-30 bp overlaps20-60 oligos directlySmall genes (1-3 kb)Error-prone; needs correction
Hierarchical Assembly2-stage overlapsUnlimited (multi-step)Large constructs (>10 kb)Stage-wise verification

Typical Fragment Counts for Gene Assembly

ConstructSizeOligo LengthOligos NeededPool Cost
Single Gene1-3 kb150-200 bp10-35Contact vendor
Large Gene3-10 kb200-300 bp20-65Contact vendor
Pathway (3-5 genes)5-15 kb200 bp50-150Contact vendor
Gene Cluster10-50 kb200-300 bp65-320Contact vendor
Variant Library (100 genes)100-300 kb total200 bp1K-3KContact vendor

Pricing varies by vendor and pool size — contact vendors directly for quotes. Excludes amplification reagents and error correction.

Checklist for Pool-Based Gene Assembly

1

Codon-Optimize Gene Sequence

Optimize for target organism codon usage. Remove problematic sequences: internal BsaI/BsmBI sites, extreme GC regions, homopolymers.

Use GC Analyzer
2

Tile Overlapping Oligos

Divide into 150-350 bp fragments with 20-40 bp overlaps. Equalize Tm of overlaps (62-70°C). Add unique amplification primer sites for each gene.

Use Tm Calculator
3

QC Oligo Sequences

Screen all oligos for synthesis problems: GC extremes, homopolymers, repeats, and hairpins. Redesign tiles around problematic sequences.

Use Batch QC
4

Order Pool & Amplify

Submit to vendor. After delivery, selectively amplify each gene's fragments using PCR with gene-specific primers. Gel-verify sizes.

5

Assemble & Verify

Gibson/Golden Gate assembly. Transform, pick colonies, sequence-verify. Apply error correction if needed (e.g., ErrASE, CorrectASE).

Use Error Rate Calculator

Frequently Asked Questions

How long of a gene can I assemble from an oligo pool?
Individual genes of 1-10 kb are routine from a single oligo pool (20-200 oligos). Pathways or gene clusters up to 50-100 kb can be assembled hierarchically: pool → fragments → sub-assemblies → final construct. Public vendor tiers differ by product: Twist standard oligo pools can support up to 350 nt while cloned pool tiers may cap at 300 nt, and IDT oPools are commonly listed up to 350 nt. Confirm the current product tier before using longer fragments.
What overlap length should I use between oligos?
For Gibson/PCA assembly: 20-40 bp overlaps with Tm 62-70°C. For Golden Gate: type IIS restriction sites (BsaI/BsmBI) generating 4 bp overhangs. Longer overlaps (30-40 bp) improve assembly efficiency but reduce the unique sequence per oligo.
How many oligos do I need to assemble a 3 kb gene?
With 200 bp oligos and 40 bp overlaps: 3000 / (200-40) = ~19 oligos. With 120 bp oligos and 30 bp overlaps: 3000 / (120-30) = ~34 oligos. Both are well within a single oligo pool order.
Can I assemble multiple genes from one oligo pool?
Yes. Include oligos for all genes in a single pool, then use gene-specific primer pairs to selectively amplify each gene's fragments. A pool of 500 oligos can encode 10-20 different genes simultaneously. This is the most cost-effective approach for combinatorial pathway assembly.

Related Gene Assembly Pages