Graduation Year

2025

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Biochemistry

Reader 1

Sampriti Mukherjee

Reader 2

Bethany Caulkins

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Terms of Use for work posted in Scholarship@Claremont.

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© 2024 Olivia K Poston

Abstract

Pseudomonas aeruginosa are Gram-negative, monotrichous bacteria responsible for acute and chronic nosocomial infections and known for their high levels of antibiotic resistance. Hierarchical regulation of flagellar gene expression in P. aeruginosa is coordinated with virulence factors, and functional flagella have been associated with increased infection. Therefore, in order to combat rising levels of infection and multidrug resistance, it is important to understand how flagellar proteins and flagellum-driven motility contribute to virulence and pathogenicity. My first aim was to purify two flagellar proteins in P. aeruginosa for future biochemical characterization: FlgB, a proximal rod protein, and FlhF, a polar landmark protein. SDS-PAGE analysis indicated that both proteins were purified, but not at concentrations high enough to move forward with antibody production. Additionally, the proteins of interests were not successfully cleaved and separated from the N-terminus polyhistidine and SUMO tags used for overexpression and purification. My second aim was to characterize the ecological significance of flagellar number and localization in a Caenorhabditis elegans model system using P. aeruginosa flagellar protein deletion mutants ∆fliC, ∆flhF, and ∆fleN. Results showed that the ∆fleN mutant demonstrated decreased lethality in C. elegans compared to other mutants and the wild-type, which all showed similar lethality. These findings show that while all of the mutants had limited motility, they all demonstrated different lethalities, suggesting that motility is likely not a contributor to virulence in this particular model. These results contribute to future work which may include elucidation of the mechanism of lethality of these particular mutants.

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