Methods for assembling DNA molecules
The invention provides compositions and methods for assembling a DNA molecule having a desired sequence. The methods involve contacting a DNA polymerase, dNTPs, and a plurality of pairs of oligonucleotides. The oligonucleotides of a pair have a portion of the desired sequence, and an internal sequence that overlaps and is complementary to an internal sequence of the other oligonucleotide of the pair, and, when arranged in order, they have at least a portion of the desired sequence. The oligonucleotides also have a 3′ or a 5′ primer binding sequence having a binding site for a primer. The oligonucleotides that correspond to the end oligonucleotides of the desired sequence also have a universal 3′ flanking sequence and a universal 5′ flanking sequence, respectively. The methods involve performing a first amplification reaction on the plurality of pairs of oligonucleotides; removing the 3′ and 5′ primer binding sequences from the plurality of pairs of oligonucleotides; and subjecting the plurality of pairs of oligonucleotides to an assembly reaction to thereby assemble the dsDNA molecule having the desired sequence.
1. A method of assembling a double-stranded DNA molecule (dsDNA) having a desired sequence comprising:
a) contacting a DNA polymerase, dNTPs, and a plurality of pairs of oligonucleotides, wherein each oligonucleotide of a pair comprises a portion of the desired sequence, and the oligonucleotides of a pair comprise an internal sequence that overlaps and is complementary to an internal sequence of the other oligonucleotide of the pair;
wherein when the plurality of pairs of oligonucleotides are arranged in order, adjacent to each other and according to their internal sequences they comprise at least a portion of the desired sequence;
wherein the oligonucleotides comprise a 3′ or a 5′ primer binding sequence that comprises at least one non-standard base;
wherein the dsDNA molecule of desired sequence has a 3′ end and a 5′ end, and the oligonucleotide pairs that comprise the 3′ and 5′ ends further comprise a universal 3′ flanking sequence and a universal 5′ flanking sequence comprised to the inside of the 3′ and 5′ primer binding sequences, respectively, and wherein the oligonucleotide pairs that do not comprise the 3′ and 5′ ends of the dsDNA molecule of the desired sequence, do not comprise a universal 3′ flanking sequence or a universal 5′ flanking sequence;
b) performing a first amplification reaction on the plurality of pairs of oligonucleotides using primers that bind to the 3′ and 5′ primer binding sequence;
c) removing the 3′ and 5′ primer binding sequences from the plurality of pairs of oligonucleotides using an enzyme that specifically cleaves the primer binding sequences at a non-standard base; and
d) subjecting the plurality of pairs of oligonucleotides to an assembly reaction to thereby assemble the dsDNA molecule having the desired sequence.
2. The method of claim 1 further comprising a step of removing at least a portion of the universal 3′ flanking sequence and the universal 5′ flanking sequence.
3. The method of claim 1 wherein the first amplification reaction comprises a denaturation phase, an annealing phase, and an extension phase.
4. The method of claim 3 wherein the amplification reaction is the polymerase chain reaction, or a variant of PCR.
5. The method of claim 1 further comprising a second, and optionally additional, amplification reactions.
6. The method of claim 1 wherein the 5′ and 3′ primer binding sequences on an oligonucleotide pair are not complementary to each other.
7. The method of claim 1 wherein the method assembles a plurality of DNA molecules of desired sequences.
8. The method of claim 7 wherein the plurality of DNA molecules comprises a plurality of distinct genes.
9. The method of claim 1 wherein the pairs of oligonucleotides are comprised on a solid support.
10. The method of claim 9 wherein the solid support is a nucleic acid array.
11. The method of claim 10 wherein at least 15 pairs of oligonucleotides are comprised on the array.
12. The method of claim 1 wherein the oligonucleotides comprise from 60 to 100 nucleotides and the primer binding sequences comprise from 8 to 30 nucleotides.
13. The method of claim 12 wherein the dsDNA molecule assembled is a nucleic acid construct selected from the group consisting of: a plasmid, an artificial chromosome, and a functional gene.
14. The method of claim 4 wherein a first pair of oligonucleotides comprises a first set of 3′ or 5′ primer binding sequences, and a second pair of oligonucleotides comprises a second set of 3′ or 5′ primer binding sequences.
15. The method of claim 1 wherein the 3′ and 5′ primer binding sequences do not comprise a restriction site for a restriction enzyme.
16. The method of claim 1 wherein the 3′ and 5′ primer binding sequences are removed by the action of one or more enzymes that specifically cleave the primer binding sequences, and wherein the one or more enzymes do not comprise a restriction enzyme.
17. The method of claim 16 wherein the one or more enzymes comprise uracil DNA glycosylase, endonuclease VIII, and exonuclease T.
18. The method of claim 1 further comprising a step of pre-determining the sequence of the desired DNA molecule.
19. The method of claim 1 wherein a plurality of oligonucleotide pairs is comprised in a single container and forms at least two couplets, and the at least two couplets comprise distinct sets of 3′ and 5′ primer binding sequences, and the primers comprise two sets of primers that bind specifically to the at least two couplets.
20. The method of claim 1 further comprising a step of forming the plurality of pairs of oligonucleotides into a plurality of couplets.
21. The method of claim 1 performed in a single container.
22. The method of claim 1 which is an automated method.
23. The method of claim 1 wherein the oligonucleotides comprised in the pairs of oligonucleotides are from about 50 to about 200 nucleotides in length.
24. The method of claim 1 wherein the dsDNA molecule assembled in the method is greater than 5 Mbp in size.
25. The method of claim 1 wherein the nucleic acid molecule of desired sequence is a scarless DNA molecule.
26. The method of claim 1 wherein step (d) comprises the use of primers that bind to the universal 3′ and 5′ flanking sequences.