An in vitro evolved precursor tRNA with aminoacylation activity.

Area of Science:

• Origin of life studies
• Molecular evolution
• Biochemistry

Background:

• Aminoacyl-tRNA synthesis is essential for protein translation.
• The RNA world hypothesis proposes RNA as the primary catalyst in early life.
• The precise mechanisms of early translation remain under investigation.

Purpose of the Study:

• To investigate the potential of RNA catalysts in early aminoacyl-tRNA synthesis.
• To demonstrate a self-charging precursor tRNA with catalytic activity.
• To explore the evolutionary origins of the genetic coding system.

Main Methods:

• In vitro evolution of a precursor tRNA with two domains: a catalytic 5'-leader sequence and an aminoacyl-acceptor tRNA.
• Characterization of the self-charging activity of the 5'-leader sequence.
• Analysis of the ribozyme's susceptibility to RNase P RNA.
• Mutational studies to identify key base-pairing interactions.

Main Results:

• An in vitro evolved precursor tRNA was created, capable of self-charging phenylalanine.
• The 5'-leader sequence acted as a cis-acting ribozyme, and its segment could aminoacylate mature tRNA in trans.
• Mutational analysis revealed specific Watson-Crick base pairing between the ribozyme and the tRNA acceptor end.
• This mechanism is similar to that observed in RNase P RNA and 23S rRNA.

Conclusions:

• Catalytic precursor tRNAs could have served as foundational elements for proto-translation systems.
• The identified RNA-based aminoacylation mechanism provides insights into the RNA world hypothesis.
• This study supports the role of RNA in the early development of the genetic code and translation.