Regulating Campylobacter jejuni flagellar gene expression: transcriptional and post-transcriptional mechanisms of control

Le, My Thanh (2013) Regulating Campylobacter jejuni flagellar gene expression: transcriptional and post-transcriptional mechanisms of control. Doctoral thesis, University of East Anglia.

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Abstract

The bacterial pathogen Campylobacter jejuni is the leading cause of foodborne
gastroenteritis in the developed world. C. jejuni flagella are crucial virulence
determinants, but the regulation of these complex organelles within different
environments is not fully understood. Moreover, regulatory RNAs are important for
virulence and flagellar gene expression in many prokaryotes, but their role in C. jejuni
biology is unknown.
The first aim was to understand flagellar regulation in acidic conditions and what effect
this has on virulence. The most acidic pH C. jejuni was able to survive was pH 3.6 and
acid-shock at this pH and pH 5 increased expression of a subset of flagellar genes and
increased invasion of intestinal epithelial cells.
The second aim of this study was to characterise the function of two paralogous small
non-coding RNAs (less than 50 nucleotides), NC1 and NC4, which were identified in
the C. jejuni NCTC11168 transcriptome and are predicted to regulate flagella gene
expression. NC1 and NC4 expression was dependent on the flagellar sigma factor,
sigma28, and post-transcriptionally regulated expression of predicted sigma54-dependent
C. jejuni flagellar gene targets in an E. coli based GFP reporter system. However,
microarray and phenotypic analysis showed no clear differences in gene expression
between NC1/NC4 deletion and over-expression mutants compared to the wild-type
strain.
The conclusions are that flagellar gene expression is regulated by acidic conditions and
C. jejuni invasion of intestinal epithelial cells may be primed in response to acid. In
addition, the transcription of NC1 and NC4 is linked to flagella expression and they
may function to post-transcriptionally regulate sigma54-dependent flagella genes in C.
jejuni. Although the biological significance of NC1 and NC4 remains unknown, this is
the first study to show that non-coding RNAs are potential regulators of gene expression
in Campylobacter.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Mia Reeves
Date Deposited: 12 Mar 2014 09:17
Last Modified: 12 Mar 2014 09:17
URI: https://ueaeprints.uea.ac.uk/id/eprint/48099
DOI:

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