Prebiotic Phosphorylation and Concomitant Oligomerization of Deoxynucleosides to form DNA

Recent demonstrations of RNA-DNA chimeras enabling RNA and DNA replication, coupled with prebiotic co-synthesis of deoxyribo- and ribo-nucleotides, have resurrected the hypothesis of co-emergence of RNA and DNA. As further support, we show that diamidophosphate (DAP) with 2-aminoimidazole (amido)phosphorylates and oligomerizes deoxynucleosides to form DNA - under conditions similar to those of ribonucleosides. The pyrimidine 5'-O-amidophosphates are formed in good (≈ 60%) yields. Intriguingly, the presence of pyrimidine nucleos(t)ides increased the yields of purine-deoxynucleotides (≈ 20%). Concomitantly, oligomerization (≈ 18-31%) is observed with predominantly 3',5'-phosphodiester DNA linkages, and some (<5%) pyrophosphates. Combined with previous observations of DAP mediated chemistries and the constructive role of RDNA chimeras, the results reported here help set the stage for systematic investigation of a systems chemistry approach of RNA-DNA coevolution.