Sequencing of d/l-DNA and XNA by Templated-Synthesis

Progress in oligonucleotide sequencing has transformed modern biology and medicine. Here we report a fast and efficient enzyme-free primer extension of PNA with reversible chain termination and its application to DNA and XNA sequencing. The approach leverages activated 4-mer PNAs that react in a templated ligation reaction at μM concentrations within minutes. We demonstrate that the fidelity of this enzyme-free primer extension benefits from reactions performed with a mixture of activated PNAs where every 4-mer has its self-complementary 4-mer. The reactions can be performed using the whole repertoire of 4-mers (256 permutations) in a parallelized manner. Using a primer in combination with its -1, -2, and -3 deletion allows for sequencing by MALDI analysis, using the increment in mass for each nucleobase assignment. Given the enzyme-free nature of this sequencing and the achiral nature of PNA, we further demonstrate that the technology can be used to sequence d- or l-DNA as well as LNA and PNA (XNA).