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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR BIOLOGY AND GENOMICS OF FOODBORNE PATHOGENS

Location: Produce Safety and Microbiology Research

Title: THE CAMPYLOBACTER JEJUNI PHOS/PHOR OPERON REPRESENTS A NON-CLASSICAL PHOSPHATE-SENSITIVE TWO-COMPONENT SYSTEM

Authors
item Wosten, Marc - UTRECHT UNIV. NETHERLANDS
item Parker, Craig
item Van Mourik, A. - UTRECHT UNIV. NETHERLANDS
item Guilhabert, Magalie
item Heijmen-Van Dijk, L. - UTRECHT UNIV. NETHERLANDS
item Van Putten, J. - UTRECHT UNIV. NETHERLANDS

Submitted to: Molecular Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 7, 2006
Publication Date: October 1, 2006
Citation: Wosten, M.M., Parker, C., Van Mourik, A., Guilhabert, M.R., Heijmen-Van Dijk, L., Van Putten, J. 2006. The Campylobacter jejuni phos/phor operon represents a non-classical phosphate-sensitive two-component system. Molecular Microbiology.62:1:278-291

Interpretive Summary: Two-component signal transduction systems play a vital role in the ability of bacteria to adapt to a changed environment by altering the gene expression in response to a wide variety of external stimuli. Here we report that the C. jejuni Cj0889 and Cj0890 genes form a two-component system. This system is activated in response to the environmental signal, phosphate starvation. It is required for optimal growth in phosphate limiting media. At the amino acid level the Cj0889/Cj0890 two-component system is not homologous to the PhoB/PhoR two-component system present in many other organisms, therefore we have designated the Cj0889/Cj0890 system as PhoS/PhoRR. The PhoS/PhoRR system is not autoregulated, but regulates the transcriptional units of the pho regulon: pstSCAB (Cj0613-Cj0616), Cj0145, and the 7 genes contained in the operon Cj0727-Cj0733. We show that the PhoRR protein binds DNA fragments containing the promoter regions upstream of these three transcriptional units. Functional analysis demonstrated that Cj0145 encoded a monomeric alkaline phosphatase homologous to Vibrio cholera PhoAvc.. In conclusion our results show that C. jejuni carries a pho regulon that is regulated by the PhoS/PhoRR system, which is functionally similar but unrelated to the classical PhoB/PhoR two-component systems.

Technical Abstract: Two-component signal transduction systems play a vital role in the ability of bacteria to adapt to a changed environment by altering the gene expression in response to a wide variety of external stimuli. Here we report that the C. jejuni Cj0889 and Cj0890 genes form a two-component system as demonstrated by phosphorylation assays. This system is activated in response to phosphate starvation and is required for optimal growth in phosphate limiting media. At the amino acid level the Cj0889/Cj0890 two-component system is not homologous to the PhoB/PhoR two-component system present in many other organisms, therefore we have designated the Cj0889/Cj0890 system as PhoS/PhoRR. Microarray analysis and real-time RT-PCR experiments revealed that the PhoS/PhoRR system is not autoregulated, but regulates the transcriptional units of the pho regulon: pstSCAB (Cj0613-Cj0616), Cj0145, and the 7 genes contained in the operon Cj0727-Cj0733. Gel shift assays demonstrated that His-tagged PhoRR protein bound DNA fragments containing the promoter regions upstream of these three transcriptional units that all carried a highly conserved DNA sequence, which we named the pho box of C. jejuni (5’-GTTTCNAAAANGTTTC-3’). Functional analysis demonstrated that Cj0145 encoded a monomeric alkaline phosphatase homologous to Vibrio cholera PhoAvc was regulated by PhoS/PhoRR system. In conclusion our results show that C. jejuni carries a pho regulon that is regulated by the PhoS/PhoRR system, which is functional similar but unrelated to the classical PhoB/PhoR two-component systems.

Last Modified: 9/1/2014
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