Nonenzymatic Template-Directed Primer Extension Using 2'-3' Cyclic Nucleotides Under Wet-Dry Cycles

Area of Science:

• Origin of Life Studies
• Prebiotic Chemistry
• Molecular Evolution

Background:

• The RNA World Hypothesis proposes early RNA molecules acted as both genetic material and catalysts.
• Previous template-directed RNA synthesis often required activated nucleotides or resulted in abasic sites.
• Nonenzymatic RNA replication is crucial for understanding life's origins.

Purpose of the Study:

• To investigate nonenzymatic template-directed primer extension using prebiotically relevant cyclic nucleotides.
• To explore the feasibility of RNA replication under simulated early Earth conditions.
• To identify conditions favoring efficient RNA monomer polymerization.

Main Methods:

• Utilized dehydration-rehydration (DH-RH) cycles at high temperature (90°C) and alkaline pH (8).
• Employed 2'-3' cyclic nucleoside monophosphates (cNMPs) as monomers for primer extension.
• Tested both canonical hydroxy-terminated (OH-primer) and amino-terminated (NH2-primer) primers.
• Investigated the effect of lipids on reaction efficiency.

Main Results:

• Successful template-directed primer extension was achieved using 2'-3' cNMPs, but not 3'-5' cNMPs.
• Up to two nucleotide additions were observed with both OH- and NH2-primers.
• Both purine and pyrimidine 2'-3' cNMPs supported primer extension, with cAMP yielding higher product.
• Lipids significantly enhanced extended product yield in cyclic CMP reactions.

Conclusions:

• This study provides proof-of-concept for nonenzymatic RNA primer extension using intrinsically activated cyclic nucleotides.
• The findings support the plausibility of RNA replication in early Earth environments.
• Cyclic nucleotides and lipids represent key components for prebiotic RNA synthesis.