Date of Award

2023

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 facultative intracellular pathogen, which relies on a network of regulation for its virulence. It contains three homologs of the ribosomal protein bS21. These three ribosomal protein homologs can independently associate with ribosomes, leading to ribosomal heterogeneity. The second homolog, bS21-2, is implicated in the positive regulation of a number of virulence proteins. Additionally, transcriptomic data indicates that bS21-2 is autoregulated. The mechanism by which this autoregulation occurs is unknown, as is the regulation of the other two homologs, bS21-1 and bS21-3. In the following chapters, I will show that bS21-1 and bS21-3 do not autoregulate their transcript. Further, I will demonstrate that the leader sequence of bS21-2 is sufficient to result in autoregulation of its transcript. And in particular, a specific portion of the leader sequence is sufficient for regulation. This regulation is potentially accomplished through the degradation of the bS21-2 transcript. Alternatively, I will show that the bS21-2 protein is not autoregulated.

I will then explore different environmental conditions to determine what conditions may up-regulate bS21-1 and bS21-3. Particularly, growth on CHA-H results in up-regulation of transcript abundance of bS21-1 and bS21-3, as compared to supplemented MHB. This growth condition leads to a subsequent increase of both bS21-1 and bS21-3 protein. In addition, low pH increases bS21-1 transcript abundance, but the effect on protein is unclear.

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