title: Divergent distribution of the sensor kinase CosS in non-thermotolerant campylobacter species and its functional incompatibility with the response regulator CosR of Campylobacter jejuni.
abstract: Two-component signal transduction systems are commonly composed of a sensor histidine kinase and a cognate response regulator, modulating gene expression in response to environmental changes through a phosphorylation-dependent process. CosR is an OmpR-type response regulator essential for the viability of Campylobacter jejuni, a major foodborne pathogenic species causing human gastroenteritis. Although CosR is a response regulator, its cognate sensor kinase has not been identified in C. jejuni. In this study, DNA sequence analysis of the cosR flanking regions revealed that a gene encoding a putative sensor kinase, which we named cosS, is prevalent in non-thermotolerant Campylobacter spp., but not in thermotolerant campylobacters. Phosphorylation assays indicated that C. fetus CosS rapidly autophosphorylates and then phosphorylates C. fetus CosR, suggesting that the CosRS system constitutes a paired two-component signal transduction system in C. fetus. However, C. fetus CosS does not phosphorylate C. jejuni CosR, suggesting that CosR may have different regulatory cascades between thermotolerant and non-thermotolerant Campylobacter species. Comparison of CosR homolog amino acid sequences showed that the conserved phosphorylation residue (D51), which is present in all non-thermotolerant Campylobacter spp., is absent from the CosR homologs of thermotolerant Campylobacter species. However, C. jejuni CosR was not phosphorylated by C. fetus CosS even after site-directed mutagenesis of N51D, implying that C. jejuni CosR may possibly function phosphorylation-independently. In addition, the results of cosS mutational analysis indicated that CosS is not associated with the temperature dependence of the Campylobacter spp. despite its unique divergent distribution only in non-thermotolerant campylobacters. The findings in this study strongly suggest that thermotolerant and non-thermotolerant Campylobacter spp. have different signal sensing mechanisms associated with the CosR regulation.
authors.affiliation: Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, and Center for Food and Bioconvergence, Seoul National University, Seoul, Korea.
authors.forename: Sunyoung
authors.initials: S
authors.lastname: Hwang
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, California, United States of America.
authors.forename: William G
authors.initials: WG
authors.lastname: Miller
authors.affiliation: Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, and Center for Food and Bioconvergence, Seoul National University, Seoul, Korea.
authors.forename: Sangryeol
authors.initials: S
authors.lastname: Ryu
authors.affiliation: School of Public Health, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Byeonghwa
authors.initials: B
authors.lastname: Jeon
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002167:Campylobacter / Q000235:genetics / Q000378:metabolism*; D002169:Campylobacter Infections; D016123:Campylobacter jejuni / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016297:Mutagenesis, Site-Directed; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D011494:Protein Kinases