Enzymatic RNA synthesis and RNase P. Evolutionary aspects

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Biochemistry

Background:

• The transition from an RNA world to a DNA world is a key event in early life.
• Transfer RNA (tRNA) plays crucial roles in modern biology, including protein synthesis.

Purpose of the Study:

• To explore the evolutionary link between primordial RNA and modern DNA worlds using tRNA recognition as a model.
• To identify conserved structural elements of tRNA responsible for enzyme recognition.

Main Methods:

• Comparative analysis of tRNA structure and function across different life forms.
• Investigating the recognition of tRNA-like structures by enzymes like RNase P.
• Examining the role of tRNA-like elements in viral RNA replication and polymerase recognition.

Main Results:

• A minimal tRNA structure (acceptor stem, T arm, linker) is sufficient for recognition by prokaryotic and eukaryotic RNase P and other tRNA enzymes.
• tRNA-like elements in viral RNAs function as replication origins.
• Recognition of similar structures by RNA polymerases as cryptic promoters is conserved.
• Modern polymerases exhibit limited substrate specificity, likely paralleling primitive polymerases.

Conclusions:

• The study proposes that proto-tRNA in the RNA world served as a replication origin and primitive telomere.
• Conserved recognition of tRNA structural motifs by enzymes suggests an evolutionary link between RNA and DNA worlds.
• Limited substrate specificity of primitive polymerases likely facilitated the formation of mixed nucleic acids during the RNA-to-DNA transition.