Widespread position-specific conservation of synonymous rare codons within coding sequences.

Area of Science:

• Molecular Biology
• Genetics
• Bioinformatics

Background:

• Synonymous rare codons are typically considered suboptimal for gene expression.
• However, protein-coding sequences often contain clusters of these rare codons.
• Previous research linked rare codons at the 5' end to increased translational efficiency.

Purpose of the Study:

• To investigate if codon rarity, rather than specific codon identity, is conserved across homologous genes.
• To determine if conserved rare codon clusters play a functional role in protein co-translational folding and organism physiology.

Main Methods:

• Comparative analysis of homologous coding sequences across diverse species (eukaryotic, bacterial, archaeal).
• Identification and localization of conserved rare codon clusters within protein domains and structural motifs.
• Correlation analysis between conserved rare codon clusters and protein function, particularly those related to growth and development.

Main Results:

• Many rare codon cluster positions are conserved across species, indicating positive selection and functional importance.
• Conserved clusters are predominantly located within protein domains, separating smaller structural motifs.
• Proteins with conserved rare codon clusters are enriched in functions related to organism growth and development.

Conclusions:

• Conserved rare codon clusters have a functional role, potentially coordinating co-translational folding of protein structural motifs.
• Synonymous codon usage can be a mechanism for modulating protein production and influencing organism physiology.
• This finding opens avenues for experimental validation of synonymous codon usage effects on functional protein production.