Stereoselectivity of Aminoacyl-RNA Loop-Closing Ligation

Area of Science:

• Origin of Life Studies
• Biochemistry
• RNA World Hypothesis

Background:

• Amino acid homochirality is a fundamental question in the origin of life.
• Enantiopure nucleotides are essential for nonenzymatic RNA replication, suggesting early nucleotide homochirality.
• The mechanism by which homochiral RNA influenced other biomolecules, like amino acids, remains unclear.

Purpose of the Study:

• To investigate if and how homochiral RNA can impose homochirality on amino acids.
• To explore aminoacyl-RNA loop-closing ligation as a mechanism for stereoselective amino acid incorporation.
• To understand the role of RNA in the selection of L-amino acids.

Main Methods:

• Examined aminoacyl-RNA loop-closing ligation reactions.
• Compared reaction rates for L-amino acids versus D-amino acids.
• Identified specific RNA sequences for selective amino acid capture.
• Investigated stereoselectivity in ligation products.

Main Results:

• Aminoacyl-RNA loop-closing ligation proceeds significantly faster with L-amino acids than D-amino acids.
• A specific RNA sequence was found to almost exclusively capture L-amino acids.
• Ligation of aminoacyl-L-RNA demonstrated inverse stereoselectivity, favoring D-amino acids.

Conclusions:

• RNA can act as a stereoselective template, influencing amino acid chirality.
• This process likely played a role in the selection of L-amino acids.
• This mechanism provides a pathway for the evolution of homochiral peptides and proteins.