title: The Campylobacter jejuni response regulator, CbrR, modulates sodium deoxycholate resistance and chicken colonization.
abstract: Two-component regulatory systems play a major role in the physiological response of bacteria to environmental stimuli. Such systems are composed of a sensor histidine kinase and a response regulator whose ultimate function is to affect the expression of target genes. Response regulator mutants of Campylobacter jejuni strain F38011 were screened for sensitivity to sodium deoxycholate. A mutation in Cj0643, which encodes a response regulator with no obvious cognate histidine kinase, resulted in an absence of growth on plates containing a subinhibitory concentration of sodium deoxcholate (1%, wt/vol). In broth cultures containing 0.05% (wt/vol) sodium deoxycholate, growth of the mutant was significantly inhibited compared to growth of the C. jejuni F38011 wild-type strain. Complementation of the C. jejuni cbrR mutant in trans restored growth in both broth and plate cultures supplemented with sodium deoxycholate. Based on the phenotype displayed by its mutation, we designated the gene corresponding to Cj0643 as cbrR (Campylobacter bile resistance regulator). While the MICs of a variety of bile salts and other detergents for the C. jejuni cbrR mutant were lower, no difference was noted in its sensitivity to antibiotics or osmolarity. Finally, chicken colonization studies demonstrated that the C. jejuni cbrR mutant had a reduced ability to colonize compared to the wild-type strain. These data support previous findings that bile resistance contributes to colonization of chickens and establish that the response regulator, CbrR, modulates resistance to bile salts in C. jejuni.
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA.
authors.forename: Brian H
authors.initials: BH
authors.lastname: Raphael
authors.forename: Sonia
authors.initials: S
authors.lastname: Pereira
authors.forename: Gary A
authors.initials: GA
authors.lastname: Flom
authors.forename: Qijing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Julian M
authors.initials: JM
authors.lastname: Ketley
authors.forename: Michael E
authors.initials: ME
authors.lastname: Konkel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001647:Bile Acids and Salts / Q000494:pharmacology; D016123:Campylobacter jejuni / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D002645:Chickens / Q000382:microbiology*; D003840:Deoxycholic Acid / Q000494:pharmacology*; D003902:Detergents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D011201:Poultry Diseases / Q000382:microbiology*; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D001647:Bile Acids and Salts; D003902:Detergents; D003840:Deoxycholic Acid