The Extracytoplasmic Protein Quality Control System in Pathogenic Campylobacterota: Its Role in Bacterial Virulence and Maintaining Cellular Envelope Proteostasis.

The cellular envelope of Gram-negative bacteria is a space where processes that are extremely important for the proper functioning of bacteria and determining their virulence take place. The extracytoplasmic protein quality control system, which includes chaperones, protein-folding catalysts, and proteases, is responsible for maintaining homeostasis in this cellular compartment. This system has been well studied in the model bacterium , but little is known about its function in other bacteria. In bacteria evolutionarily distant from Enterobacteriaceae, the protein quality control system appears to function differently. For example, in the phylum Campylobacterota, a number of homologs of folding factors and proteases, whose functions are important for maintaining homeostasis in the periplasm of , have not been identified. Instead, there are quality control components that have no similar counterparts in the Enterobacteriaceae. In this review, we present the current state of knowledge on the extracytoplasmic protein quality control system in the model Campylobacterota, and .