Mutation of PEB4 alters the outer membrane protein profile ofCampylobacter jejuni

Abstract

Campylobacter jejuni is a significant cause of human gastroenteritis worldwide. In an attempt to further define bacterial factors that influence infectivity, Cj0596 was identified as playing a role in C. jejuni virulence. Cj0596 is a periplasmic chaperone that is similar to proteins involved in outer membrane protein (OMP) folding in other bacteria. Mutation of cj0596 caused an alteration in the levels of eight OMPs, compared to wild-type bacteria. Replacement of the cj0596 mutation with the wild-type cj0596 gene restored a wild-type OMP profile. The altered OMP profile in the cj0596 mutant was accompanied by significant changes in several virulence properties, including an increase in the ability to autoagglutinate, increased susceptibility to several antimicrobial agents, and increased biofilm formation. In summary, mutation of cj0596 alters the C. jejuni OMP profile and leads to changes in OMP-related phenotypes involved in C. jejuni pathogenesis.

Different Contributions of HtrA Protease and Chaperone Activities to Campylobacter jejuni Stress Tolerance and Physiology

“…While SurA does not possess protease activity, the chaperone activities of SurA and HtrA may functionally overlap in C. jejuni, as HtrA is upregulated in a surA mutant (3). SurA facilitates outer membrane protein biogenesis in E. coli (60), and consistent with this function, the outer membrane profile of C. jejuni is altered by a surA mutation (54). However, HtrA may have a more dominant role than SurA in maintaining periplasmic protein homeostasis, since a lack of SurA does not result in upregulation of DnaK and ClpB (53).…”

The Virulence Factor PEB4 (Cj0596) and the Periplasmic Protein Cj1289 Are Two Structurally Related SurA-like Chaperones in the Human Pathogen Campylobacter jejuni

“…C. jejuni does not appear to contain an Skp homologue, and PEB4 is currently the only protein implicated in OMP assembly, based on changes in OMP abundance in peb4 mutants (25)(26)(27). The 2.2-Å structure determined here reveals a monomer composed of independently folded chaperone and PPIase domains, connected by a short linker region.…”

“…Asakura et al (25) showed that a cj0596 null mutant made in strain NCTC11168 was considerably less adherent to INT407 cells than the wild-type, displayed a reduced level and duration of intestinal colonization of a mouse model of infection, and was deficient in biofilm formation. A cj0596-null mutant made in the highly pathogenic strain 81-176 was also less able to colonize mice but was more motile than the parent strain (26,27). This mutant actually showed an increased propensity to invade INT407 cells but was not significantly affected in adhesion or intracellular survival.…”

“…Despite these strain differences, these studies revealed a significant growth defect in the cj0596 mutant and, most significantly, iTRAQ-based proteomic methods revealed decreases in the abundance of several outer membrane and periplasmic proteins in the NCTC11168 cj0596 mutant (25). Mass spectrometric identification of proteins from one-and two-dimensional gels of the strain 81-176 cj0596 mutant also showed a variety of protein expression changes, including a decrease in three outer membrane proteins: Omp50, major OMP, and the fibronectin binding-protein CadF (26,27), although some other proteins were increased in expression.…”

“…The abundant periplasmic PEB4 protein has previously been implicated in OMP assembly in C. jejuni (25)(26)(27). The cognate gene (cj0596) encodes a predicted periplasmic PPIase and is conserved in all strains that have been genome sequenced to date.…”