Methods for assembling nucleic acids
The invention provides methods of assembling a DNA molecule having a desired sequence. The methods involve contacting a DNA ligase with a plurality of short oligonucleotides to be assembled and performing the ligase chain reaction to thereby generate a set of polynucleotides. Oligonucleotides in the plurality overlap with and are complementary to a sequence of at least one other oligonucleotide in the plurality, and at least 50% of the oligonucleotides in the plurality are 6-30 nucleotides in length. The set of polynucleotides produced are contacted with a DNA polymerase and dNTPs in a mixture to join the set of polynucleotides and thereby create a DNA molecule having a desired sequence by polymerase chain assembly. The method allows for production of oligonucleotides of any length having very high sequence fidelity to a desired sequence.
1. A method of assembling a DNA molecule having a desired sequence comprising:
a) contacting a DNA ligase with short oligonucleotides of 8-25 nucleotides in length and comprising at least a portion of the desired sequence of the DNA molecule to be assembled to create a mixture,
wherein at least a portion of the short oligonucleotides in the mixture overlap with and are complementary to a portion of the sequence of at least one other short oligonucleotide in the mixture, and wherein at least two of the short oligos abut one another when bound to their complementary sequence(s),
b) performing a ligase chain reaction on the mixture to thereby generate a set of polynucleotides, and
c) contacting the set of polynucleotides with a DNA polymerase and dNTPs to join the set of polynucleotides, and to thereby assemble the DNA molecule having the desired sequence
wherein the method is performed as a one-step reaction.
2. The method of claim 1 , wherein the set of polynucleotides is joined by a DNA assembly reaction.
3. The method of claim 2 , further comprising combining multiple pools of the set of DNA fragments to join the DNA fragments via PCA (Polymerase Cycling Assembly).
4. The method of claim 1 , wherein the set of polynucleotides is joined by polymerase cycling assembly.
5. The method of claim 1 , further comprising contacting the short oligonucleotides with a kinase before or simultaneous with the contacting of the short oligonucleotides with the DNA ligase.
6. The method of claim 1 , wherein the DNA ligase is a thermostable DNA ligase.
7. The method of claim 6 , wherein the DNA ligase is Taq ligase.
8. The method of claim 1 , wherein the abutting short oligos comprise a phosphorylated 5′ terminal nucleotide of a first short oligo and a 3′ hydroxyl on a 3′ terminal nucleotide of a second short oligo.
9. The method of claim 1 , further comprising amplifying the DNA molecule having the desired sequence using the polymerase chain reaction.
10. The method of claim 1 , wherein the method is performed in solution.
11. The method of claim 1 , wherein the DNA molecule having the desired sequence is 100-10,000 base pairs in length.
12. The method of claim 1 , wherein the DNA molecule having the desired sequence is 100-5,000 base pairs in length.
13. The method of claim 1 , wherein the desired sequence further comprises a universal 5′ flanking sequence and a universal 3′ flanking sequence.
14. The method of claim 1 , wherein the mixture comprises at least 10 short oligonucleotides.
15. The method of claim 14 , wherein the mixture comprises at least 20 short oligonucleotides.
16. The method of claim 1 , wherein the mixture comprises from 2 to 250 short oligonucleotides.
17. The method of claim 1 , wherein the short oligonucleotides are 8-18 nucleotides in length.
18. The method of claim 1 , wherein at least 50% of the short oligonucleotides in the mixture are 16-18 nucleotides in length.
19. The method of claim 1 , wherein at least 75% of the oligonucleotides in the mixture are 8-18 nucleotides in length at the start of the method.
20. The method of claim 1 , wherein the method is performed without the use of restriction enzymes.
21. The method of claim 1 , wherein assembled DNA molecule of desired sequence has an error rate of fewer than 1 error per 2000 base pairs.
22. The method of claim 21 , wherein the assembled DNA molecule of desired sequence has an error rate of fewer than 1 error per 14000 base pairs.
23. The method of claim 22 , wherein the error rate is obtained in the method without the use of error correction enzymes.
24. The method of claim 1 , wherein the mixture of short oligonucleotides comprises at least 15 pools of oligonucleotides.
25. The method of claim 1 , wherein the assembly is done entirely in vitro.
26. The method of claim 1 , wherein the oligonucleotides are 8-mers or 16mers.
27. The method of claim 1 , wherein the DNA molecule is assembled with scarless assembly.
28. The method of claim 1 , wherein the short oligonucleotides comprise more than 64 short oligonucleotides.
29. The method of claim 1 , wherein the method is conducted without the use of linker, adaptor, or spacer DNA molecules.
30. The method of claim 1 , wherein the ligase chain reaction comprises at least 5 cycles of denaturation, annealing, and ligation.
31. The method of claim 1 , wherein less than 10% of the oligonucleotides in the mixture are longer than 21 nucleotides in length.
32. The method of claim 1 , wherein less than 1% of the oligonucleotides in the mixture are longer than 21 nucleotides in length.