Recognition of β-strand motifs by RseB is required for σ(E) activity in Escherichia coli.

Gram-negative bacteria react to misfolded proteins in the envelope through a myriad of different stress response pathways. This cohort of pathways allows the bacteria to specifically respond to different types of damage, and many of these have been discovered to have key roles in the virulence of bacterial pathogens. Misfolded outer membrane proteins (OMPs) are typically recognized by the σ(E) pathway, a highly conserved envelope stress response pathway. We examined the features of misfolded OMPs with respect to their ability to generate envelope stress responses. We determined that the secondary structure, particularly the potential to form β strands, is critical to inducing the σ(E) response in an RseB-dependent manner. The sequence of the potential β-strand motif modulates the strength of the σ(E) response generated by the constructs. By understanding the details of how such stress response pathways are activated, we can gain a greater understanding of how bacteria survive in harsh environments.