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A PAS domain-containing regulator controls flagella-flagella interactions in Campylobacter jejuni.

ABSTRACT: The bipolar flagella of the foodborne bacterial pathogen Campylobacter jejuni confer motility, which is essential for virulence. The flagella of C. jejuni are post-translationally modified, but how this process is controlled is not well understood. In this work, we have identified a novel PAS-domain containing regulatory system, which modulates flagella-flagella interactions in C. jejuni. Inactivation of the cj1387c gene, encoding a YheO-like PAS6 domain linked to a helix-turn-helix domain, resulted in the generation of a tightly associated "cell-train" morphotype, where up to four cells were connected by their flagella. The morphotype was fully motile, resistant to vortexing, accompanied by increased autoagglutination, and was not observed in aflagellated cells. The ?cj1387c mutant displayed increased expression of the adjacent Cj1388 protein, which comprises of a single endoribonuclease L-PSP domain. Comparative genomics showed that cj1387c (yheO) orthologs in bacterial genomes are commonly linked to an adjacent cj1388 ortholog, with some bacteria, including C. jejuni, containing another cj1388-like gene (cj0327). Inactivation of the cj1388 and cj0327 genes resulted in decreased autoagglutination in Tween-20-supplemented media. The ?cj1388 and ?cj0327 mutants were also attenuated in a Galleria larvae-based infection model. Finally, substituting the sole cysteine in Cj1388 for serine prevented Cj1388 dimerization in non-reducing conditions, and resulted in decreased autoagglutination in the presence of Tween-20. We hypothesize that Cj1388 and Cj0327 modulate post-translational modification of the flagella through yet unidentified mechanisms, and propose naming Cj1387 the Campylobacter Flagella Interaction Regulator CfiR, and the Cj1388 and Cj0327 protein as CfiP and CfiQ, respectively.

SUBMITTER: Reuter M

PROVIDER: S-EPMC4519771 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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A PAS domain-containing regulator controls flagella-flagella interactions in Campylobacter jejuni.

Reuter Mark M Periago Paula M PM Mulholland Francis F Brown Helen L HL van Vliet Arnoud H M AH

Frontiers in microbiology 20150730

The bipolar flagella of the foodborne bacterial pathogen Campylobacter jejuni confer motility, which is essential for virulence. The flagella of C. jejuni are post-translationally modified, but how this process is controlled is not well understood. In this work, we have identified a novel PAS-domain containing regulatory system, which modulates flagella-flagella interactions in C. jejuni. Inactivation of the cj1387c gene, encoding a YheO-like PAS6 domain linked to a helix-turn-helix domain, resu ...[more]

PMID: 26284050

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Project description:Campylobacter jejuni is a leading cause of bacterially derived gastroenteritis. A previous mutant screen demonstrated that the heme uptake system (Chu) is required for full colonization of the chicken gastrointestinal tract. Subsequent work identified a PAS domain-containing regulator, termed HeuR, as being required for chicken colonization. Here we confirm that both the heme uptake system and HeuR are required for full chicken gastrointestinal tract colonization, with the heuR mutant being particularly affected during competition with wild-type C. jejuni Transcriptomic analysis identified the chu genes-and those encoding other iron uptake systems-as regulatory targets of HeuR. Purified HeuR bound the chuZA promoter region in electrophoretic mobility shift assays. Consistent with a role for HeuR in chu expression, heuR mutants were unable to efficiently use heme as a source of iron under iron-limiting conditions, and mutants exhibited decreased levels of cell-associated iron by mass spectrometry. Finally, we demonstrate that an heuR mutant of C. jejuni is resistant to hydrogen peroxide and that this resistance correlates to elevated levels of catalase activity. These results indicate that HeuR directly and positively regulates iron acquisition from heme and negatively impacts catalase activity by an as yet unidentified mechanism in C. jejuni IMPORTANCE: Annually, Campylobacter jejuni causes millions of gastrointestinal infections in the United States, due primarily to its ability to reside within the gastrointestinal tracts of poultry, where it can be released during processing and contaminate meat. In the developing world, humans are often infected by consuming contaminated water or by direct contact with livestock. Following consumption of contaminated food or water, humans develop disease that is characterized by mild to severe diarrhea. There is a need to understand both colonization of chickens, to make food safer, and colonization of humans, to better understand disease. Here we demonstrate that to efficiently colonize a host, C. jejuni requires iron from heme, which is regulated by the protein HeuR. Understanding how HeuR functions, we can develop ways to inhibit its function and reduce iron acquisition during colonization, potentially reducing C. jejuni in the avian host, which would make food safer, or limiting human colonization.

Dataset Information

A PAS domain-containing regulator controls flagella-flagella interactions in Campylobacter jejuni.

Publications

A PAS domain-containing regulator controls flagella-flagella interactions in Campylobacter jejuni.

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