Date of Award

2020

Degree Type

Thesis

Degree Name

Master of Science in Biological and Environmental Sciences (MSBES)

Specialization

Cell and Molecular Biology

Department

Cell & Molecular Biology

First Advisor

Kathryn Ramsey

Abstract

Francisella tularensis is a Gram-negative, facultative intracellular bacterial pathogen and the causative agent of the potentially fatal human disease tularemia (Sjöstedt, 2007). Like many pathogens, F. tularensis contains a number of proteins encoded by a variety of genes that are critical to its ability to cause disease including virulence factors and anti-virulence factors. F. tularensis encodes an anti-virulence factor called PriM that inhibits replication inside macrophage, one of its key host cell types. The goal of this study was to elucidate the molecular mechanism for how PriM functions as anti-virulence factor in F. tularensis subspecies holarctica live vaccine strain (LVS). Using information about the structure of PriM, we created strains producing mutant PriM proteins to test the importance of specific structural features to PriM’s function as an anti-virulence factor. We also took a genetic approach, initiating study of mutant F. tularensis cells that re-gained the ability to grow in macrophage despite a genetic background that should permit PriM production and thereby prevent intramacrophage growth. We found that a putative binding pocket in PriM may be key to its ability to prevent intramacrophage growth. We also identified a gene previously unlinked to F. tularensis virulence whose modification promotes intramacrophage replication and determined that PriM regulation is more complex than previously appreciated. Continuing our work to determine how PriM functions as an anti-virulence factor may allow us to identify bacterially-encoded anti-virulence pathways to exploit in the development of future anti-microbial therapeutics for F. tularensis and potentially other pathogenic organisms.

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