Common 5S rRNA variants are likely to be accepted in many sequence contexts

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Bioinformatics

Background:

• RNA sequences evolve under structural and functional constraints, defining their 'structure space'.
• Predicting which sequences belong to a specific RNA structure space is crucial for understanding RNA evolution.
• Bacterial 5S ribosomal RNA (rRNA) serves as a model system to investigate these principles.

Purpose of the Study:

• To test the hypothesis that frequently observed sequence changes in naturally occurring 5S rRNAs are widely accepted in various sequence contexts.
• To identify principles for predicting sequence inclusion within the 5S rRNA structure space.
• To evaluate the functional validity of introduced sequence variants in a heterologous cellular environment.

Main Methods:

• Defined operational criteria for 'Vibrio region' and 'highly variable position' in 5S rRNA sequences.
• Generated 14 sequence variants (point and base-pair changes) identified as highly variable.
• Introduced these variants into the Vibrio proteolyticus 5S rRNA sequence and assessed their functionality in an E. coli cellular context.

Main Results:

• 93% (13/14) of highly variable sequence variants were functional as 5S rRNA in E. coli.
• 86% (6/7) of variants present in the Vibrio region but not meeting stringent variability criteria were functional.
• Only 2 out of 7 variants seldom or never seen in the Vibrio region were potentially valid, indicating lower acceptance.

Conclusions:

• Sequence changes occurring multiple times in a local RNA sequence space are generally accepted in other sequences within the same region.
• The frequency and context of sequence variations are key predictors of their evolutionary viability.
• This finding supports the principle that common evolutionary 'solutions' are robust and adaptable across related RNA sequences.