I have a sequence of ssDNA that I would like to directly ligate an Illumina sequencing adaptor to. As long as I have done the end repair (remove phosphates), can I directly ligate the adaptor to the ssDNA without polyA tailing? I want to avoid using a polyA tail because the end of the sequence contains important information, and I do not want it lost during tail trimming steps in the data analysis. Then I would denature the DNA and collect the complementary strand and repeat for the other end. Is the ligation efficiency decreased due to the lack of the polyA pairing with the T overhang of the adaptor?
Or is there an enzyme that adds a fixed number of A to the end so I know how many A's to trim?
Thanks in advance!