A Potential Role for Aminoacylation in Primordial RNA Copying Chemistry

Abstract

Aminoacylated tRNAs are the substrates for ribosomal protein synthesis in all branches of life, implying an ancient origin for aminoacylation chemistry. In the 1970s, Orgel and colleagues reported potentially prebiotic routes to aminoacylated nucleotides and their RNA templated condensation to form amino acid bridged dinucleotides. However, it is unclear whether such reactions would have aided or impeded nonenzymatic RNA replication. Determining whether aminoacylated RNAs could have been advantageous in evolution prior to the emergence of protein synthesis remains a key challenge. We therefore tested the ability of aminoacylated RNA to participate in both templated primer extension and ligation reactions. We find that at low magnesium concentrations that favor fatty acid-based protocells, these reactions proceed orders of magnitude more rapidly than when initiated from the cis-diol of unmodified RNA. We further demonstrate that amino acid bridged RNAs can act as templates in a subsequent round of copying. Our results suggest that aminoacylation facilitated nonenzymatic RNA replication, thus outlining a potentially primordial functional link between aminoacylation chemistry and RNA replication. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=106 SRC="FIGDIR/small/413815v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@1e5f29dorg.highwire.dtl.DTLVardef@19b2a99org.highwire.dtl.DTLVardef@9aad0org.highwire.dtl.DTLVardef@ad47f7_HPS_FORMAT_FIGEXP M_FIG C_FIG