Second strand direct
Methods and compositions are provided herein for preparing high-throughput cDNA sequencing libraries.
1. A method for tagging a cDNA polynucleotide, the method comprising:
providing a double-stranded mRNA: cDNA hybrid comprising a first strand cDNA polynucleotide having a 5′ end and a 3′ end and hybridized to a complementary mRNA having a 5′ end and a 3′ end, wherein the 5′ end of the first strand cDNA polynucleotide comprises a first adapter sequence or complement thereof;
synthesizing one or more second strand cDNA polynucleotides that are complementary to and hybridized to the first strand cDNA polynucleotide, wherein the synthesizing comprises:
i) hybridizing random primers to the first strand cDNA of the mRNA: cDNA hybrid and extending hybridized random primers to form the one or more second strand cDNA polynucleotides;
contacting the double-stranded cDNA polynucleotide with an adapter-loaded tagmentase, thereby forming a reaction mixture comprising a tagged double-stranded cDNA polynucleotide comprising a first end and a second end, wherein the first end comprises the first adapter sequence and complement thereof, and the second end comprises a second adapter sequence and complement thereof,
forming partitions comprising (a) amplification primers comprising at least one primer comprising a partition-specific barcode and (b) the first strand cDNA and the second strand cDNAs and
amplifying the first and second strand cDNAs with the amplification primers.
2. The method of claim 1 , wherein the 5′ end of the mRNA is single-stranded.
3. The method of claim 1 , wherein the amplification primers comprise (i) a first amplification primer that selectively hybridizes to the first adapter sequence and comprises a first sequencing-platform-specific adapter sequence, and wherein (ii) a second amplification primer that selectively hybridizes to the second adapter sequence and comprises a second sequencing-platform-specific adapter sequence, thereby producing a sequencing platform-specific cDNA amplicon.
4. The method of claim 1 , wherein the providing the double-stranded mRNA: cDNA hybrid comprises contacting the mRNA with a reverse transcriptase and a first strand synthesis primer to thereby extend the first strand synthesis primer in an mRNA template-directed DNA polymerase reaction, wherein the first strand synthesis primer comprises a 3′ poly-thymine end region and a 5′ end comprising the first adapter sequence or complement thereof, thereby synthesizing the first strand cDNA polynucleotide hybridized to the complementary mRNA, and wherein the 5′ end of the first strand cDNA comprises the first adapter sequence or complement thereof.
5. The method of claim 4 , wherein the method comprises performing the mRNA template-directed DNA polymerase reaction in a reaction mixture comprising mRNA, and the contacting the mRNA: cDNA hybrid with the enzyme comprising RNase H activity is performed in a reaction mixture comprising mRNA from at least 10 cells.
6. The method of claim 4 , wherein the method comprises performing the mRNA template-directed DNA polymerase reaction in a reaction mixture comprising mRNA from at least 10 cells.
7. The method of claim 4 , wherein the first strand synthesis primer comprises a molecular barcode.
8. The method of claim 1 , wherein the 5′ end of the first strand cDNA polynucleotide comprises a molecular barcode.
9. The method of claim 3 , wherein: the first end of the tagged double-stranded cDNA polynucleotide comprises adapter sequence A and the second end of the tagged double-stranded cDNA polynucleotide comprises adapter sequence B, and the method comprises selectively amplifying from the reaction mixture the tagged double-stranded cDNA polynucleotide, thereby producing a sequencing platform-specific cDNA amplicon, by contacting the tagged double-stranded cDNA polynucleotide with the first amplification primer, the second amplification primer, and a third amplification primer,
wherein the first amplification primer comprises a 3′ region having a sequence A′ that selectively hybridizes to the first adapter sequence A and the first amplification primer further comprises a 5′ region comprising a first sequencing-platform-specific adapter sequence; and
wherein the second amplification primer and third amplification primer each comprise a 5′ region comprising a second sequencing-platform-specific adapter sequence, and a 3′ region, wherein the 3′ region of the second or third amplification primer has a sequence B′ that selectively hybridizes to the second adapter sequence B.
10. The method of claim 1 , wherein the contacting the double-stranded cDNA polynucleotide with the adapter-loaded tagmentase comprises introducing a homoadapter-loaded tagmentase comprising two identical polynucleotide adapters into the reaction mixture comprising the double-stranded cDNA polynucleotide, thereby attaching one of the polynucleotide adapters to the second end of the double-stranded cDNA.
11. The method of claim 10 , wherein the attaching is performed in a reaction mixture that does not comprise an adapter-loaded tagmentase comprising a polynucleotide adapter that is different from the two identical polynucleotide adapters of the homoadapter-loaded tagmentase.
12. The method of claim 1 , wherein the contacting the double-stranded cDNA polynucleotide with the adapter-loaded tagmentase comprises:
introducing a heteroadapter-loaded tagmentase comprising two structurally distinct polynucleotide adapters into the reaction mixture comprising the double-stranded cDNA polynucleotide; or
introducing into the reaction mixture comprising the double-stranded cDNA polynucleotide a first and a second homoadapter-loaded tagmentase wherein the first homoadapter-loaded tagmentase comprises a polynucleotide adapter and the second homoadapter tagmentase comprises a structurally distinct polynucleotide adapter,
thereby attaching one of the polynucleotide adapters to the second end of the double-stranded cDNA.
13. The method of claim 1 , wherein the double-stranded cDNA polynucleotide contacted with the adapter-loaded tagmentase comprises an original first strand cDNA polynucleotide hybridized to an original second strand cDNA polynucleotide.
14. The method of claim 1 , wherein the partitions are droplets in an emulsion.
15. The method of claim 1 , wherein the partitions are microwells, nanowells, or picowells.
16. A method for tagging a plurality of cDNA polynucleotides, the method comprising performing a method according to claim 1 with a plurality of structurally distinct mRNA:cDNA hybrids.
17. The method of claim 16 , wherein the plurality of structurally distinct mRNA:cDNA hybrids comprise mRNA from a single cell.
18. The method of claim 16 , wherein the plurality of structurally distinct mRNA:cDNA hybrids comprise mRNA from at least 10 cells.