UCSF

The cell envelope in gram-negative bacteria is a specialized barrier that must be constantly remodeled to suit the bacteria's needs. To accomplish this end bacteria have numerous systems in place that monitor, repair, and reconfigure their cell envelope as needed. One of the most critical systems in E.coli that participates in this function is the σ^E dependent cell envelope stress response. Although much is known about the protein encoded components of this critical system, little was known about the components that encode for small regulatory RNAs (sRNAs).

This work clearly establishes sRNAs as a central component of the σ^E dependent cell envelope stress response. We uncovered many new σ^E dependent sRNAs, including a novel sRNA, Reg26, which shares some characteristics with the other previously known σ^E dependent sRNAs MicA and RybB. Not only does this work fully characterize the regulatory breadth of MicA, RybB, and Reg26, it characterizes the importance of these sRNAs by assessing their contributions to cell survival. Overall this work demonstrates how these sRNAs, in concert with the protein encoded component of the response, enables σ^E to monitor and maintain a trait as complex as envelope homeostasis.