Evolution of Nucleotide Punctuation Marks: From Structural to Linear Signals

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Genetics

Background:

• Nucleotide synthesis signals (DNA replication, RNA transcription) may have evolutionary links to translation.
• Evolutionary transitions might involve signals combining primary and secondary nucleotide structures.
• Mitochondrial replication initiation provides a potential model for this evolutionary scenario.

Purpose of the Study:

• To propose an evolutionary hypothesis for nucleotide synthesis signals.
• To investigate the dual role of signals in transcription and translation.
• To analyze the function of the natural circular code X in human mitochondrial RNAs.

Main Methods:

• Comparative analysis of nucleotide sequences in mitochondrial RNAs (delRNAs) and other mitochondrial genome regions.
• Examination of homopolymer triplet distribution in delRNAs.
• Analysis of the natural circular code X's role in frameshift regulation.

Main Results:

• delRNAs exhibit a 2x higher frequency of homopolymer triplets compared to other mitochondrial regions.
• The natural circular code X (20 specific codons) is implicated in regulating frameshifts during both transcription and translation.
• Observations support the hypothesis that translational signals originated from transcriptional signals.

Conclusions:

• The natural circular code X demonstrates a dual role in transcription and translation, confirming its evolutionary origin from transcriptional signals.
• The findings support the hypothesis that signals evolved from multi- to unidimensional structures and were transferred from transcription to translation.
• Mitochondrial replication initiation serves as a valid model for this evolutionary pathway.