From peptides to DNA: All required steps can be catalyzed

Area of Science:

• Origin of life studies
• Prebiotic chemistry
• Molecular evolution

Background:

• The RNA world hypothesis suggests RNA handled heredity and catalysis in early life.
• Alternative theories propose catalytic peptides preceded RNA, with sequences later reverse-translated into genes.

Purpose of the Study:

• To experimentally investigate the feasibility of converting peptide sequences into DNA.
• To assess if existing molecular machinery could catalyze the steps of hypothetical reverse translation.

Main Methods:

• Step-wise peptide degradation by amino peptidase to release amino acids.
• Amino acid identification and codon matching using aptazymes.
• Ligation of codon triplets into RNA for reverse transcription into DNA.

Main Results:

• Demonstrated that peptide degradation, amino acid-to-codon matching via aptazymes, and RNA ligation are all catalyzable reactions.
• Showed that these steps can form a processive system, potentially converting peptide sequences into DNA.

Conclusions:

• The experimental evidence supports the possibility of reverse translation as a mechanism in early evolution.
• The hypothesis that catalytic peptides played a role before polynucleotides warrants further consideration.