Abstract
Campylobacter jejuni infection is a leading bacterial cause of gastroenteritis and a common antecedent leading to Gullian-Barré syndrome. Our previous data suggested that the RNA-binding protein CsrA plays an important role in regulating several important phenotypes including motility, biofilm formation, and oxidative stress resistance. In this study, we compared the proteomes of wild type, csrA mutant, and complemented csrA mutant C. jejuni strains in an effort to elucidate the mechanisms by which CsrA affects virulence phenotypes. The putative CsrA regulon was more pronounced at stationary phase (111 regulated proteins) than at mid-log phase (25 regulated proteins). Proteins displaying altered expression in the csrA mutant included diverse metabolic functions, with roles in amino acid metabolism, TCA cycle, acetate metabolism, and various other cell processes, as well as pathogenesis-associated characteristics such as motility, chemotaxis, oxidative stress resistance, and fibronectin binding. The csrA mutant strain also showed altered autoagglutination kinetics when compared to the wild type. CsrA specifically bound the 5’ end of flaA mRNA, and we demonstrated that CsrA is a growth-phase dependent repressor of FlaA expression. Finally, the csrA mutant exhibited reduced ability to colonize in a mouse model when in competition with the wild type, further underscoring the role of CsrA in C. jejuni colonization and pathogenesis.
Highlights
Campylobacter jejuni is a leading bacterial cause of gastroenteritis throughout the world
C. jejuni strain 81–176 [14], it isogenic csrA mutant, and complemented mutant strain csrA/pJF11 [5] were stored at -80°C in Mueller Hinton (MH) broth (0.2% beef extract, 1.75% acid digest of casein, 0.15% starch) containing 20% (v:v) glycerol and grown on MH agar at 42°C in a tri-gas incubator (85% N2, 10% CO2, 5% O2) or in microaerophilic atmospheres generated within Mitsubishi AnaeroPack jars using AnaeroPouch microaerophilic gas generator sachets (Remel)
C. jejuni cells were grown overnight at 42°C diluted into fresh MH media and allowed to grow in parallel to either mid-log phase (OD600 = 0.5) or to stationary phase (OD600 = 1.0) at 42°C
Summary
Campylobacter jejuni is a leading bacterial cause of gastroenteritis throughout the world. As a pathogen of significant public health importance, C. jejuni has been extensively studied; our understanding of the exact mechanisms by which it causes disease remain incomplete. Most frequently associated with poultry due to a commensal relationship with avian species and the frequent occurrence of disease following the ingestion of undercooked chicken, PLOS ONE | DOI:10.1371/journal.pone.0156932. Most frequently associated with poultry due to a commensal relationship with avian species and the frequent occurrence of disease following the ingestion of undercooked chicken, PLOS ONE | DOI:10.1371/journal.pone.0156932 June 3, 2016
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