Evolution of the ribosome at atomic resolution.

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Biochemistry

Background:

• The ribosome, a fundamental molecular machine, evolved over billions of years.
• Ribosomal RNA (rRNA) structure and size vary across species, correlating with complexity.
• Understanding rRNA expansion processes offers insights into early life and ribosome evolution.

Purpose of the Study:

• To investigate the mechanisms of ribosomal RNA (rRNA) expansion.
• To reconstruct models of primordial ribosomes and trace their evolutionary history.
• To identify key evolutionary phases in ribosome development.

Main Methods:

• Comparative analysis of 3D rRNA structures from bacteria, yeast, and metazoans.
• Identification and analysis of "insertion fingerprints" in rRNA structures.
• Conceptual reversal of rRNA expansion processes to model ancestral ribosomes.

Main Results:

• rRNA expansion occurs through specific processes like helix insertion and elongation.
• Distinctive atomic resolution "insertion fingerprints" mark rRNA growth.
• Models of pre-last universal common ancestor (pre-LUC A) rRNAs were generated.

Conclusions:

• Ribosome evolution can be traced by analyzing rRNA expansion patterns and fingerprints.
• Specific expansion mechanisms shaped the peptidyl transferase center and conserved core.
• Distinct evolutionary phases involved the acquisition of coding, translocation, and tunnel elaboration.