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Title: Regulation of flagellar biogenesis in Campylobacter jejuni
Author: Kamal, Nahid.
ISNI:       0000 0001 3594 2338
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2005
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Campylobacter jejuni, the cause of acute bacterial enteritis, is a Gram-negative, microaerophilic, spiral bacterium. The single polar flagellum of the organism has an important role inc ausing disease. In the published genome a nnotation of C. j ejuni some of the key regulatory flagellar genes are missing. Therefore the regulatory control of flagellar biogenesis is still not clear in the organism. FliK, the protein that controls the length of the flagellar hook and is also involved in switching of secretory pathway specificity in Salmonella, is among the regulatory proteins missing in the organism. We have identified the missingjliK gene in C. jejuni, which is Cj0041, and the homologue in its close relative Helicobacter pylori, HP0906. Although the protein encoded by Cj0041 is not readily identified by BLAST search against the major databases, a BLAST query of the C. jejuni genome database (Sanger Institute) with the FliK sequence from Aeromonas hydrophila identifies the Cj0041 gene product at E=0.056. Cj0041 knock-out mutants in two strains (NCTC11168 and 81116) 0 f C. jejuni were non-motile and showed a polyhook phenotype, which is in line with that of FliK mutants in Salmonella. SDS PAGE and mass spectrometry analysis with 'flagellar' filament proteins from Cj0041 mutants revealed increased production of FlgE hook protein in mutants compared to wild-type and indicated the synthesis of these polyhooks with mainly FlgE proteins. Microarray analysis of these mutants, verified by real-time PCR, showed overexpression of flagellar and other regulatory genes dependent on cr54 , one of the sigma factors involved in flagellar biogenesis, and provided a clear delineation of the cr54-dependent regulon. These results established the importance of Cj0041 or jliK in regulation of flagellar biogenesis in C. jejuni. We also have established by two-hybrid analysis the roles of Cj 1464 as jlgM and Cj 1465 asjlgN, two other key missing genes in the gene annotation of the organism. The roles of other flagellar genes such asjliS,jliD and Cj0848c were also studied to get a clear picture of flagellar biogenesis in C. jejuni. This study established that the organism shares most of the key regulatory flagellar genes found in model organisms like Salmonella and made it possible to define the regulation of flagellar biogenesis in C. jejuni more clearly than it has been described to date.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available