Prebiotically plausible mechanisms increase compositional diversity of nucleic acid sequences

Area of Science:

• Origin of Life Studies
• Biochemistry
• Computational Biology

Background:

• Biological information increase is crucial for early life, particularly for encoding functional molecules in the RNA world.
• Non-enzymatic polymerization of ribonucleotides leads to compositionally biased sequences due to variations in nucleotide properties.
• Natural selection requires molecules with some activity to initiate the process of evolution.

Purpose of the Study:

• To investigate whether the emergence of diverse nucleic acid sequences was by chance or if prebiotically plausible reactions could counteract chemical biases.
• To determine if chemical mechanisms can increase the probability of finding functional ribozymes.

Main Methods:

• In silico simulations using a two-letter alphabet to model template-directed ligation and concatenation.
• Experimental verification of DNA sequences as templates for ligation to assess compositional diversity.

Main Results:

• Simulations showed that template-directed ligation and high concatenation rates counteract compositional bias, favoring longer sequences and stable folding.
• Experimental results confirmed that unbiased DNA sequences are more efficient templates for ligation, enhancing compositional diversity.

Conclusions:

• Prebiotically plausible chemical mechanisms, such as nucleic acid polymerization and ligation, can promote a diverse pool of longer, potentially structured molecules.
• These mechanisms could have facilitated the early appearance of functional activity, setting the stage for the origin of life.