Polymerase ribozyme efficiency increased by G/T-rich DNA oligonucleotides

Area of Science:

• Biochemistry
• Origin of Life Studies
• Molecular Evolution

Background:

• The RNA world hypothesis proposes RNA acted as both genetic material and catalyst in early life.
• RNA polymerase ribozymes are key to understanding RNA replication but suffer low efficiency and template specificity.
• Weak, sequence-independent binding to primer/template substrates limits ribozyme polymerization efficiency.

Purpose of the Study:

• To improve the polymerization efficiency of RNA polymerase ribozymes.
• To overcome limitations in self-replication capabilities of laboratory-evolved ribozymes.
• To investigate methods for enhancing sequence-independent substrate binding.

Main Methods:

• Modification of the primer/template binding region of RNA polymerase ribozymes.
• Truncation of the RNA heptanucleotide primer.
• Replacement of RNA primers with randomized DNA oligomers (15 nt) with varying G/T content.

Main Results:

• Truncating the 3'-terminus of the RNA heptanucleotide increased primer extension 10-fold on a specific template.
• Replacing RNA primers with randomized 15 nt DNA oligomers dramatically improved polymerization across multiple templates.
• Optimal DNA primer sequences contained 60% G and 40% T, suggesting weak, non-specific base-pairing interactions.

Conclusions:

• Modifying primer binding substrates, especially with randomized DNA, significantly enhances RNA polymerase ribozyme efficiency.
• Low-specificity base-pairing interactions mediated by DNA oligomers could be vital for RNA world function.
• These findings offer insights into the mechanisms that could have supported early life's replication.