Thesis
Pathogenic mechanisms of Campylobacter jejuni: Regulation of Campylobacter invasion antigen B
Master of Science (MS), Washington State University
2004
Handle:
https://hdl.handle.net/2376/176
Abstract
Campylobacter jejuni, a Gram-negative, spiral shaped bacterium is the leading cause of gastroenteritis in humans worldwide. However, little is known regarding the mechanisms Campylobacter employs to cause disease. Previous work has shown that Campylobacter jejuni secretes a set of proteins known as the Campylobacter invasion antigens (Cia proteins). Recent research has shown that the flagella apparatus acts as a type III secretion system allowing the delivery of the Cia proteins to intestinal epithelial cells. Furthermore, research has shown that the expression of the cia genes is upregulated in the presence of bile salts and fetal bovine serum. Given that an environmental signal was required to induce the expression of the cia genes, I sought to determine how the cia genes were regulated. I generated single crossover mutants of ten of the response regulators and one AraC-like transcriptional activator that are present in the Campylobacter NCTC 11168 genome. Upon subjecting the single crossover mutants to secretion assays, I determined that Cj0890c, Cj1024c (flgR), and Cj1042c (AraC-like) were secretion negative and may play a role in the regulation of the cia genes. Next, I generated double crossover mutants to validate this secretion negative phenotype. In addition I generated double crossover mutants of s28 and s54, Cj0061c (fliA) and Cj0670 (rpoN). Secretion assays of the double crossover mutants revealed that Cj0061c (fliA), Cj0890c, and Cj1042c (AraC-like) were secretion positive and do not play a role in the regulation of the cia genes. Cj0670 (rpoN) and Cj1024c (flgR) were found to be secretion negative, suggesting that Cj0670 (rpoN) and Cj1024c (flgR) may play a role in the regulation of the cia genes. Upon subjecting Cj0670 (rpoN) and Cj1024c (flgR) to RT-PCR and immunoblot analysis we observed that the ciaB was still transcribed and translated in the Cj0670 (rpoN) and Cj1024c (flgR) and therefore do not play a role in the regulation of ciaB. This finding strengthens the result that the flagella apparatus serves as the type III secretion system for the export of the Cia proteins. Collectively these data suggest that ciaB is under the control of s70.
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Details
- Title
- Pathogenic mechanisms of Campylobacter jejuni
- Creators
- Gary Andrew Flom
- Contributors
- Michael E. Konkel (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Molecular Biosciences, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Identifiers
- 99900525288101842
- Language
- English
- Resource Type
- Thesis