Codon usage and modular interactions between messenger RNA coding regions and small RNAs in Escherichia coli

Area of Science:

• Bacterial molecular biology
• Gene regulation mechanisms
• RNA-RNA interactions

Background:

• Small RNAs (sRNAs) are crucial regulators of bacterial gene expression.
• sRNAs modulate translation initiation, mRNA stability, and ribosome progression.
• Codon usage and tRNA availability may influence sRNA-mRNA interactions.

Purpose of the Study:

• To investigate codon bias in sRNA-mRNA interactions.
• To explore differences in codon usage and tRNA availability between sRNA-regulated and non-sRNA-regulated mRNAs.
• To analyze these parameters within the specific interaction regions of mRNAs.

Main Methods:

• Comparative analysis of codon adaptation index (CAI) and tRNA adaptation index (tAI).
• Focus on sRNAs with multiple mRNA targets.
• Identification of conserved motifs in sRNA-mRNA interacting regions.

Main Results:

• Differences in CAI and tAI were observed between sRNA-regulated and non-sRNA-regulated mRNAs.
• sRNA-mRNA interaction sites were enriched in unpreferred codons decoded by scarce tRNAs.
• Multi-target sRNAs possess modular segments recognizing conserved mRNA motifs.

Conclusions:

• Bacterial sRNAs in E. coli target mRNA coding regions with predicted slow ribosome speeds.
• Conserved motifs within sRNA-mRNA interaction sites are recognized by the same sRNA across multiple targets.