Studies Towards Understanding the Biosynthesis of Methyl Phosphoramidates found in Campylobacter jejuni

• Author / Creator

  Ashmus, Roger A

• The human pathogen Campylobacter jejuni is the leading cause of food-borne gastroenteritis, causing more foodborne illnesses than Salmonella, Shigella, and Listeria combined. Of the approximate 5.3 million people infected every year in North America alone, approximately 1/1000 will develop the post-infectious paralytic disorder Guillain–Barré syndrome. In addition, the Public Health Agency of Canada has recently reported that approximately 90% of all chickens in supermarkets are infected with C. jejuni. C. jejuni produces a capsular polysaccharide (CPS) that is an important virulence factor involved in colonization and invasion. The structure of C. jejuni CPS varies widely from strain to strain and is often functionalized with a range of phase-variable modifications. One of these 
unique and rare modifications is an O-methyl phosphoramidate (MeOPN) motif, which is found in over 70% of C. jejuni strains. The role of these MeOPNs is
 unknown, but recent studies have demonstrated that MeOPN-functionalized
 CPS plays a significant role in modulating several aspects of the immune response. Thus, there is good
evidence for a biological role for the MeOPN group. Access to these MeOPN motifs could lead to the development of vaccines against C. jejuni and targeting the enzymes involved in its biosynthesis could lead to new therapeutic agents for the treatment of C. jejuni infections. However, before such agents can be identified, better characterization of these biosynthetic enzymes and their substrates are required. This thesis will focus on the MeOPN motif in two parts. The first part describes the development of a reliable method for the synthesis of the MeOPN motif and assess its stability through various chemical transformations. This will enable access to these rare and unique modifications for the potential development of vaccines against C. jejuni. Part two of this thesis will describe work directed at unraveling the biosynthesis of the MeOPN motifs. More specifically, we will describe work to demonstrate enzyme activity for the two phosphoramidate transferases found in the C. jejuni strain 11168H. This work, when complete, will provide insights that could be used to development of inhibitors against these proteins and possible new therapeutic agents against C. jejuni.

• Subjects / Keywords

  • C. jejuni
  • Phosphoramidate
  • Carbohydrates

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R39G5GV2B

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.