Talk on Friday 01:45-02:00pm submitted by Xiwen Jia
A study of non-templated polymerization for understanding the emergence of RNA from prebiotic mixtures
Xiwen Jia (Department of Chemistry and Chemical Biology, Harvard University), Stephanie J. Zhang (Department of Chemistry and Chemical Biology, Harvard University), Lijun Zhou (Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital), Jack W. Szostak (Department of Chemistry and Chemical Biology, Harvard University; Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital; HHMI)
Prebiotically plausible synthesis of ribonucleotides (RNA) shares similar reaction pathway as arabino- (ANA) and threo-nucleotides (TNA). We investigated the non-templated primer extension using a mixture of activated ribo-, arabino- and threo-nucleotides in the light of understanding the process of emergence of RNA from prebiotic mixtures. We found that the mechanism of non-templated primer extension occurs primarily through bridged dinucleotides. In non-templated primer extension with pre-activated monomers, RNA and ANA shares similar extension profile including rate and yield, while TNA barely has any extension. For competition experiments, we used a prebiotically plausible spontaneous air dry process to speed up non-templated primer extension. We observed that TNA is slightly filtered out whereas ANA has similar incorporation compared to RNA depending on the initial abundance of nucleotides. We concluded that the selection bias based on identities of nucleotides in the non-templated polymerization is close to non-existent. However, the later templated copying step exerts strong incorporation preference towards ribonucleotides, thus generating mostly RNA oligomers.
Keywords: Genetics, Oligomers, Monomers