Large-scale mapping of sequence-function relations in small regulatory RNAs reveals plasticity and modularity

Area of Science:

• Molecular Biology
• Genomics
• Systems Biology

Background:

• The genomics era has shifted focus from identifying functional elements to quantifying their properties like specificity and efficiency.
• Bacterial small RNAs (sRNAs) are crucial regulators of gene expression, but their sequence-function relationships require quantitative characterization.

Purpose of the Study:

• To establish a quantitative map between bacterial regulatory RNA sequences and their efficiency in modulating target gene expression.
• To investigate the quantitative relationships between sRNA structural/energetic features and their regulatory activity.

Main Methods:

• Generalized the sort-seq method to accurately quantify the efficiency of a large library of sRNA sequence variants.
• Focused on two E. coli sRNAs, DsrA and RyhB, analyzing their regulation of both repressed and activated targets.

Main Results:

• Precisely identified functional elements within the DsrA and RyhB sRNAs.
• Established quantitative relationships between sRNA structural and energetic features and their regulatory efficiency.
• Characterized numerous nucleotide interactions, supporting a model where molecular rigidity enhances specificity.
• Revealed a modular design for both sRNAs, separating structural stability and target binding requirements.

Conclusions:

• The study provides a quantitative framework for understanding sRNA sequence-function relationships.
• sRNA modularity and structural rigidity are key determinants of regulatory specificity and efficiency.
• This work advances our understanding of gene regulation in bacteria at a quantitative level.