Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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The role of the Cj0440c gene in Campylobacter jejuni

ABSTRACT: Cj0440c encodes a putative transcriptional regulator. To determine the role of Cj0440c in C.jejuni, we knocked out Cj0440c in the wild-type strain (S) to obtain the Cj0440c mutants (SM). Then we compared the transcriptome of the Cj0440c mutant with that of the parent strain using DNA microarray. These comparisons identified 19 genes that showed aM-bM-^IM-%2-fold change in expression in SM. The differentially expressed genes in SM encode proteins involved in flagellar biosynthesis, O-linked glycosylation and hypothetical proteins with unknown fuctions. Cj0440c may regulate flagellar structural element expression or as a compenent of flagellar complex co-expressed with other flagellar genes. Subsequent experiments demonstrated that inactivation of Cj0440c affected corresponding phenotypes of C.jejuni, including broken flagella, weaker motility and reduced colonization ability in chickens. These findings indicate that Cj0440c governs the expression of multiple genes related to flagellar biosynthesis and O-linked glycosylation. This study provides favorable evidence for completing the information of the Campylobacter jejuni genome. An eight chip study using total RNA recoverd from four separate wild-type cultures of Campylobacter jejuni NCTC111168 (S) and four separate cultures of a mutant strain, Campylobacter jejuni NCTC11168 delta- Cj0440c (SM), in which Cj0440c is deleted. Each chip measures the expression level of 1634 genes from Campylobacter jejuni NCTC11168.

ORGANISM(S): Campylobacter jejuni subsp. jejuni NCTC 11168 = ATCC 700819

SUBMITTER: Xia Fang

PROVIDER: E-GEOD-49256 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:During colonization in the host gastrointestinal tract, the enteric bacteria Campylobacter jejuni is exposed to a variety of signaling molecules including the catecholamine hormones epinephrine (Epi) and norepinephrine (NE). NE has been determined to stimulate the growth of C. jejuni as well as increase its pathogenicity. To investigate the mechanisms of NE or Epi on the biology of C. jejuni, the global gene expression profiles of C. jejuni NCTC 11168 cultured in iron-restricted medium were analyzed in response to NE or Epi. Totally, 183 and 156 genes were differentially expressed by NE and Epi respectively, with 102 differentially expressed genes common between the two treatments. These genes are involved in diverse cellular functions including iron uptake systems, motility, virulence, oxidative stress response, nitrosative stress tolerance, enzyme metabolism, DNA repair and metabolism and ribosomal protein biosynthesis. Adherence to and invasion of Caco-2 cells by C. jejuni were enhanced upon exposure to NE or Epi. These results indicated that NE and Epi have similar effects on the gene expression of C. jejuni and that the effects on gene expression may contribute to elucidate the mechanisms on interaction between host and C. jejuni. Transcriptional profiles were analyzed using microarray to compared the epinephrine (Epi) or norepinephrine (NE) treated and untreated Campylobacter jejuni NCTC 11168. NE or Epi treated and untreated cultures of C. jejuni NCTC 11168 were collected at the mid-log phase (?36 h cultures). Three (for NE or Epi treated culture) or four (for untreated control culture) independent biological replicates were performed. Total RNA was extracted using RiboPure™-Bacteria Kit (Ambion, Life Technologies) according to the manufacturer’s instructions. The quality and quantity of total RNA were determined by an Agilent Bioanalyzer 2100. Total RNA was amplified and labeled by Low Input Quick Amp Labeling Kit, One-Color, following the manufacturer’s instructions. Labeled cRNA were purified by RNeasy mini kit (QIAGEN, GmBH, Germany). Each Slide was hybridized with 600ng Cy3-labeled cRNA using Gene Expression Hybridization Kit (Agilent technologies, Santa Clara, CA, US) in Hybridization Oven, according to the manufacturer’s instructions. After 17 hours hybridization, slides were washed in staining dishes with Gene Expression Wash Buffer Kit (Agilent technologies, Santa Clara, CA, US), followed the manufacturer’s instructions. Slides were scanned by Agilent Microarray Scanner with default settings, Dye channel: Green, Scan resolution=5?m, PMT 100%, 10%, 16bit. Data were extracted with Feature Extraction software 10.7. Raw data were normalized by Quantile algorithm, Gene Spring Software 11.0. The genes with fold change ? 1.5 and P < 0.05 were selected as differentially expressed.

Project description:C. jejuni, a spiral-shaped gram-negative bacterium, is a leading bacterial cause of human foodborne illness. Acute disease is associated with C. jejuni invasion of the intestinal epithelium. Further, maximal host cell invasion requires the secretion of proteins termed Campylobacter invasion antigens (Cia). As bile acids are known to alter the pathogenic behavior of other gastrointestinal pathogens, we hypothesized that the virulence potential of Campylobacter may be triggered by the bile acid deoxycholate (DOC). In support of this hypothesis, culturing C. jejuni with a physiologically relevant concentration of DOC significantly altered the kinetics of cell invasion as evidenced by gentamicin-protection assays. In contrast to C. jejuni harvested from Mueller-Hinton (MH) agar plates, C. jejuni harvested from MH agar plates supplemented with DOC demonstrated Cia secretion as judged by metabolic labeling experiments. DOC was also found to induce the expression of the ciaB gene as judged by B-galactosidase reporter assays and real-time RT-PCR. Microarray analysis revealed that DOC induced the expression of virulence genes (i.e., ciaB, cmeABC, dccR, and tlyA). In summary, we demonstrate that it is possible to enhance the pathogenic behavior of C. jejuni by modifying the culture conditions. These results provide a foundation to identify genes expressed by C. jejuni in response to in vivo-like culture conditions. Keywords: Stress response For the expression profiling arrays, an indirect comparison of gene expression was performed, where the expression profile of the C. jejuni F38011 cultured in the presence and absence of DOC was measured separately on different slides as described previously (26). Briefly, Cy5 labeled reference DNA from the C. jejuni F38011 strain was mixed with Cy3 labeled test cDNA (C. jejuni F38011 cultured in the presence or absence of DOC) and hybridized to the Campylobacter cDNA array (26) on separate slides. DNA microarrays were scanned using an Axon GenePix 4000B microarray laser scanner (Axon Instruments, Union City, CA) and the data for spot and background intensities were processed using the GenePix 4.0 software. To compensate for any effect of the amount of template and uneven Cy-dye incorporation, data normalization was performed as previously described (26). For the comparison of genes differentially expressed in the presence and absence of DOC,six hybridization measurements were generated per biological experiment (three technical replicate arrays and two replicate features per array).

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The role of the Cj0440c gene in Campylobacter jejuni

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