Correlation between Shine--Dalgarno sequence conservation and codon usage of bacterial genes.

Area of Science:

• Molecular Biology
• Genomics
• Bioinformatics

Background:

• Codon usage bias influences gene expression.
• Shine-Dalgarno (SD) sequences are crucial for translation initiation in prokaryotes.
• Understanding the relationship between codon bias and SD sequence conservation can elucidate translation regulation.

Purpose of the Study:

• To investigate the correlation between codon usage bias and SD sequence conservation across nine prokaryotic genomes.
• To determine if this correlation varies among different prokaryotic species.

Main Methods:

• Calculated codon usage bias using the codon adaptation index (CAI).
• Assessed SD sequence conservation by aligning predicted SD motifs with 5' untranslated region (5'UTR) sequences.
• Analyzed complete genome sequences of nine prokaryotes.

Main Results:

• A clear correlation between CAI values and SD sequence conservation was observed in *Escherichia coli*, *Bacillus subtilis*, *Haemophilus influenzae*, *Archaeoglobus fulgidus*, *Methanobacterium thermoautotrophicum*, and *Methanococcus jannaschii*.
• Genes with higher CAI values showed more conserved SD sequences in these organisms.
• No significant relationship was found in *Mycoplasma genitalium*, *Mycoplasma pneumoniae*, and *Synechocystis*.

Conclusions:

• Codon usage bias and SD sequence conservation are linked in many prokaryotes, suggesting a co-evolutionary relationship.
• This correlation likely impacts translation initiation and overall translation efficiency.
• Species-specific variations in this correlation highlight diverse regulatory strategies in prokaryotic gene expression.