The origin and evolution of the ribosome

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Biochemistry

Background:

• Investigating the origin and evolution of the ribosome's active site.
• Utilizing taxonomic block structures of ribosomal proteins and RNA interactions.
• Comparing bacterial and archaeal ribosome structures.

Purpose of the Study:

• Elucidate the origin and early evolution of the ribosome's active site.
• Analyze differences between the small and large subunit active sites.
• Determine the evolutionary timeline of ribosomal subunit components.

Main Methods:

• Comparative analysis of ribosomal protein structures.
• Examination of RNA-protein interactions within bacterial and archaeal ribosomes.
• Identification of conserved and specific sequence blocks in ribosomal proteins.

Main Results:

• The small subunit's decoding site lacks a self-folding RNA segment, unlike the large subunit's peptidyl transfer center (PTC).
• Protein contacts in the decoding site involve universal sequence blocks, while PTC contacts are largely bacterial/archaeal-specific.
• These distinctions suggest the PTC originated earlier than the decoding site.

Conclusions:

• The peptidyl transferase center (PTC) of the large ribosomal subunit likely evolved before the decoding site of the small subunit.
• A precursor to the modern large ribosomal subunit may have consisted of a single self-folding RNA and short peptides.
• This suggests a simpler, RNA-centric origin for the early ribosome.