Linked target capture
The invention generally relates to sequencing library preparation methods. In certain embodiments, two or more template nucleic acids are joined together by a linking molecule, such as a PEG derivative. Identical copies of a nucleic acid fragment or both strands of a duplex fragment may be linked together. The linked nucleic acids are amplified, creating linked amplicons. Emulsion PCR with linked primers creates linked template nucleic acids for seeding sequencing clusters and errors can be readily identified by their presence on only one of the linked fragments.
1. A method of preparing a DNA preparation, the method comprising:
providing an aqueous partition that includes (i) a nucleic acid fragment that includes universal priming sequences, (ii) a first linked target capture probe comprising a target-specific probe that anneals to a sense strand of the nucleic acid fragment and is blocked from extension and is linked to a first probe-dependent universal primer, (iii) a second linked target capture probe comprising a target-specific probe that anneals to an antisense strand of the nucleic acid fragment and is blocked from extension and is linked to a second probe-dependent universal primer, and (iv) a first linked universal primer linked via a linker at a 5′ portion of the first linked universal primer to a 5′ portion of a second linked universal primer;
binding the first target-specific probe to the sense strand, annealing the first probe-dependent universal primer to one of the universal priming sequences in the sense strand, and extending the first probe-dependent universal primer to make a copy of the sense strand;
binding the second target-specific probe to the antisense strand, annealing the second probe-dependent universal primer to one of the universal priming sequences in the antisense strand, and extending the second probe-dependent universal primer to make a copy of the antisense strand;
annealing the first linked universal primer to the copy of the sense strand, and annealing the second linked universal primer to the copy of the antisense strand; and
extending the first linked universal primer and the second linked universal primer in the partition to create a complex comprising joined copies of the nucleic acid fragment.
2. The method of claim 1 , further comprising performing a sequencing reaction with the complex to determine a sequence of a target.
3. The method of claim 2 , further comprising identifying a base at one position in the target as a true variant based on a signal from the sequencing reaction and identifying an error when the signal indicates that bases at corresponding second positions in the complex are not the same.
4. The method of claim 2 , further comprising conducting an amplification reaction with the complex to create copies of the sense strand and copies of the antisense strand.
5. The method of claim 1 , wherein the partition uses one selected from the group consisting of emulsions, droplets, or wells.
6. The method of claim 2 , wherein the linker comprises a solid support.
7. The method of claim 6 , wherein the solid support is selected from the group consisting of a microbead, a bead, a channel wall, a microchip, and a surface.
8. The method of claim 6 , further comprising conducting an amplification reaction with the complex to create a plurality of copies of sense strand and the antisense strand.
9. The method of claim 8 , wherein the universal priming sequences have been added to the nucleic acid fragment in adaptors that include sense-specific barcodes that are used to confirm the presence of both the sense strand and the anti sense strand in the sequencing reaction.
10. The method of claim 1 , wherein the first linked universal primer and the second linked universal primer anneal to the universal priming sequences.
11. The method of claim 10 , further comprising, prior to the providing step, ligating adaptors to the nucleic acid fragment, wherein the adaptors comprise the universal priming sequences.
12. The method of claim 11 , wherein the adaptors further comprise cluster identification sequences.
13. The method of claim 1 , wherein the complex comprising the joined copies of the nucleic acid fragment includes a first copy of the nucleic acid fragment linked to a second copy of the nucleic acid fragment that form the seed for a single sequencing reaction on a flow cell.
14. The method of claim 13 , wherein the first copy of the nucleic acid fragment and the second copy of the nucleic acid fragment are substantially identical and linked to each other in phase to prevent binding therebetween.
15. The method of claim 14 , wherein the complex comprises amplification products attached to beads.
16. The method of claim 1 , wherein a partition comprises a droplet of an emulsion, wherein the linker is a bead, and the method comprises:
conducting an amplification reaction whereby the complex includes amplification products linked to the bead;
breaking the emulsion; and
loading the amplification products onto a flow cell of a sequencing instrument.
17. The method of claim 16 , further comprising performing a sequencing reaction with the amplification products to determine a sequence of the target.
18. The method of claim 17 , wherein the sequencing reaction incorporates fluorescently labeled nucleotides into copies of the amplification products.
19. The method of claim 18 , wherein a position in the amplification products that was amplified without error generates fluorescence that is the same among products of the sequencing reaction.
20. The method of claim 18 , wherein a position in the amplification products that was amplified with polymerase error generates fluorescence that is not the same among products of the sequencing reaction.
21. The method of claim 1 , wherein the universal priming sequences are in adaptors that have been ligated to the nucleic acid fragment.