Use of Genome-Wide Expression Profiling and Mutagenesis To Study the Intestinal Lifestyle of Campylobacter jejuni

Department of Physiological Sciences , Oklahoma State University - Stillwater, SWO, Oklahoma, United States
Infection and Immunity (Impact Factor: 3.73). 04/2005; 73(3):1797-810. DOI: 10.1128/IAI.73.3.1797-1810.2005
Source: PubMed


Campylobacter jejuni is the most common bacterial cause of diarrhea worldwide. To colonize the gut and cause infection, C. jejuni must successfully compete with endogenous microbes for nutrients, resist host defenses, persist in the intestine, and ultimately
infect the host. These challenges require the expression of a battery of colonization and virulence determinants. In this
study, the intestinal lifestyle of C. jejuni was studied using whole-genome microarray, mutagenesis, and a rabbit ileal loop model. Genes associated with a wide range
of metabolic, morphological, and pathological processes were expressed in vivo. The in vivo transcriptome of C. jejuni reflected its oxygen-limited, nutrient-poor, and hyperosmotic environment. Strikingly, the expression of several C. jejuni genes was found to be highly variable between individual rabbits. In particular, differential gene expression suggested that
C. jejuni extensively remodels its envelope in vivo by differentially expressing its membrane proteins and by modifying its peptidoglycan
and glycosylation composition. Furthermore, mutational analysis of seven genes, hspR, hrcA, spoT, Cj0571, Cj0178, Cj0341, and fliD, revealed an important role for the stringent and heat shock response in gut colonization. Overall, this study provides new
insights on the mechanisms of gut colonization, as well as possible strategies employed by Campylobacter to resist or evade the host immune responses.

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    • "InsertionalinactivationwasusedtodeterminetheroleofCj1388 andCj0327proteinsinC.jejuni.Mutantswerecreatedinthe wild-typebackground.Tomakeadoublecj1388cj0327mutant, thecj0327disruptionconstruct(Cmr)wastransformedintothe cj1388(Kmr)background.Althoughcj0327hasbeenproposed tobeanessentialgene(Stintzietal.,2005),thecj0327mutants FIGURE3|Inactivationofthecj1387c,cj1388,andcj0327genesdoes notdecreaseswarmingmotility.Brucellabrothsupplementedwith0.4% agarand0.01%TTCwereinoculatedwith5µlofovernightcultureand "
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    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 Δcj1387c 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 Δcj1388 and Δcj0327 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.
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    • "The outer membrane protein Cj0178 (CtuA) was characterized as a receptor for the iron-binding host glycoproteins ferri-transferrin, ferri-lactoferrin and ferri-ovotransferrin (Miller et al., 2008). A cj0178 mutant strain of C. jejuni NCTC 11168 showed a severe colonization defect in chicken infection experiments (Palyada et al., 2004) and a slightly attenuated phenotype in the rabbit ileal loop model (Stintzi et al., 2005). The chuABCDZ (cj1613c-cj1617) gene cluster is widespread in C. jejuni and encodes for an iron uptake system that facilitates the utilization of the host compounds like hemoglobin and hemin as iron sources (Pickett et al., 1992; Ridley et al., 2006). "
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    • "This suggests that the peptidoglycan layer of these strains may be different, and may influence their ability to survive within host cells. Stintzi et al. have shown that C. jejuni extensively remodels its envelope in vivo by differentially expressing its membrane proteins and by modifying its peptidoglycan and glycosylation composition [26]. Moreover, Frirdich et al. found that mutation of the peptidoglycan DL-carboxypeptidase pgp1 of C. jejuni resulted in a loss of spiral morphology, deficiency in chicken colonisation, defects in biofilm formation and motility, enhanced secretion of IL-8 and increased activation of Nod1 [27], providing further evidence of the involvement of the peptidoglycan layer of Campylobacter species in their pathogenic potential. "
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