Discovery boosts theory that life on Earth arose from RNA-DNA mix


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Chemists at Scripps Research have made a discovery that supports a surprising new view of how life originated on our planet.

In a study published in the chemistry journal Angewandte Chemie, they demonstrated that a simple compound called diamidophosphate (DAP), which was plausibly present on Earth before life arose, could have chemically knitted together tiny DNA building blocks called deoxynucleosides into strands of primordial DNA.

The finding is the latest in a series of discoveries, over the past several years, pointing to the possibility that DNA and its close chemical cousin RNA arose together as products of similar chemical reactions, and that the first self-replicating molecules—the first life forms on Earth—were mixes of the two.

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the paper:

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.