The Role of in Campylobacter jejuni Beyond Intercellular Signaling.

The full role of the gene in the biological processes, such as essential amino acid synthesis, nitrogen and pyruvate metabolism, and flagellar assembly, of Campylobacter jejuni has not been clearly described to date. Therefore, in this study, we used a comprehensive approach at the cellular and molecular levels, including transcriptomics and proteomics, to investigate the key role of the gene and compared C. jejuni 11168Δ ( mutant) and C. jejuni NCTC 11168 (wild type) strains. Transcriptomic analysis of the mutant grown under optimal conditions revealed upregulation of mutant metabolic pathways when normalized to wild type, including oxidative phosphorylation, carbon metabolism, citrate cycle, biosynthesis of secondary metabolites, and biosynthesis of various essential amino acids. Interestingly, induction of these metabolic pathways was also confirmed by proteomic analysis, indicating their important role in energy production and the growth of C. jejuni. In addition, genes important for the stress response of C. jejuni, including nutrient starvation and oxidative stress, were upregulated. This was also evident in the better survival of the mutant under starvation conditions than the wild type. At the molecular level, we confirmed that metabolic pathways were upregulated under optimal conditions in the mutant, including those important for the biosynthesis of several essential amino acids. This also modulated the utilization of various carbon and nitrogen sources, as determined by Biolog phenotype microarray analysis. In summary, transcriptomic and proteomic analysis revealed key biological differences in tricarboxylic acid (TCA) cycle, pyruvate, nitrogen, and thiamine metabolism as well as lipopolysaccharide biosynthesis in the mutant. Campylobacter jejuni is the world's leading foodborne bacterial pathogen of gastrointestinal disease in humans. C. jejuni is a fastidious but widespread organism and the most frequently reported zoonotic pathogen in the European Union since 2005. This led us to believe that C. jejuni, which is highly sensitive to stress factors (starvation and oxygen concentration) and has a low growth rate, benefits significantly from the gene. The role of this gene in the life cycle of C. jejuni is well known, and the expression of regulates many phenotypes, including motility, biofilm formation, host colonization, virulence, autoagglutination, cellular adherence and invasion, oxidative stress, and chemotaxis. Surprisingly, this study confirmed for the first time that the deletion of the gene strongly affects the central metabolic pathway of C. jejuni, which improves its survival, showing its role beyond the intercellular signaling system.