Pathogenic bacteria employ a number of mechanisms to induce infection and survive in host tissues, including toxin secretion and the formation of protective multicellular structures called biofilms. Type IV Pili (T4P) are highly conserved organelles essential for both the establishment of infection and biofilm maturation. The goal of this research is to gain a molecular level understanding of the function of the highly dynamic T4P of Pseudomonas aeruginosa. The pilMNOPQ operon encodes 5 members of a transmembrane complex that facilitates pilus function. While PilQ is the putative outer membrane secretin through which the pilus exits the cell, the roles of the PilM/N/O/P proteins are less well defined. Using both in vivo and in vitro techniques our characterization of PilP has provided significant insight into organization of the apparatus. PilP is an inner membrane lipoprotein essential for T4P function, but lipidation is dispensable, suggesting that its interactions with other T4P components are sufficient for PilP function. We showed that PilN/O/P form a stable heterotrimer when expressed in E. coli, and we suggest that they form a similar subcomplex in P. aeruginosa. Additionally we were able to show that PilP is also able to interact with a periplasmic fragment of the outer membrane pore protein PilQ. Structural and bioinformatics studies suggest that the organization of PilN/O/P/Q complex is similar to that of the transenvelope complex of another important Gram-negative virulence factor – the Type II Secretion System (T2SS). Our structural and functional characterization of PilP, the PilN/O/P complex and the striking similarities between the T4P and T2S systems, as well as important differences that make each molecular machine unique, will be presented.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/43398 |
| Date | 16 December 2013 |
| Creators | Tammam, Stephanie |
| Contributors | Howell, P. Lynne |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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