Searching for Possible Ancestors of RNA: The Self-Assembly Hypothesis for the Origin of Proto-RNA
There are currently two main schools of thought regarding the origins of RNA. In one school, RNA is considered to be a product of nonenzymatic, prebiotic reactions. In the other, RNA is considered to be a product of chemical and/or biological evolution. The numerous challenges to demonstrating a plausible prebiotic synthesis of RNA support the hypothesis that life started with an ancestral RNA-like polymer, or proto-RNA. If RNA is an “invention” of early life, then it is logical to assume that identifying the chemical structure of proto-RNA, and intermediate pre-RNAs, would require exploration of a seemingly insurmountable number of possible proto-RNA building blocks and prebiotic reactions. Here we report progress toward finding a proto-RNA that is the product of molecular self-assembly. Results obtained thus far demonstrate that seemingly minor changes to the structure of the extant building blocks of RNA (e.g., the substitution of uracil by barbituric acid) alleviate several long-standing problems associated with finding a prebiotic synthesis for RNA.
We thank Profs. Frank A. L. Anet, Ram Krishnamurthy, Gary B. Schuster, and Loren Dean Williams, who have been valuable collaborators and consultants on much of the work described in this chapter from our laboratory. This work was supported by the NSF and the NASA Astrobiology Program, under the NSF Center for Chemical Evolution (CHE-1504217) and the NASA Exobiology Program NNX13AI02G.
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