The Cpx envelope stress response regulates and is regulated by small noncoding RNAs

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Physiology

Background:

• Escherichia coli utilizes ~30 two-component systems for environmental sensing.
• Small noncoding RNAs (sRNAs) posttranscriptionally regulate gene expression via mRNA base pairing.
• The CpxAR two-component system manages adaptive responses to protein misfolding in bacterial envelopes.

Purpose of the Study:

• Investigate the role of sRNAs within the CpxAR two-component system.
• Determine if sRNAs are part of the Cpx regulon.
• Elucidate the regulatory functions of identified sRNAs in the Cpx response.

Main Methods:

• CpxR binding site analysis at promoter regions of sRNA genes.
• Quantitative analysis of sRNA gene expression.
• Assessment of sRNA roles in modulating Cpx pathway activity and target gene regulation.

Main Results:

• sRNAs were identified as members of the Cpx regulon for the first time.
• CpxR directly regulates the expression of two sRNAs: cyaR and rprA.
• CyaR contributes to a feed-forward loop enhancing YqaE expression.
• RprA provides negative feedback on Cpx activity, independent of its known targets.

Conclusions:

• sRNAs (cyaR and rprA) are integral components of the CpxAR regulatory network.
• These sRNAs enable sophisticated fine-tuning of the Cpx pathway.
• sRNA-mediated regulation enhances bacterial survival under envelope stress conditions.