Date Thesis Awarded

5-2024

Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)

Department

Biology

Advisor

Mark Forsyth

Committee Members

Isabelle Taylor

Gamze Bulut

Abstract

Helicobacter pylori is a gram-negative spiral-shaped bacterium that infects the gastric epithelium and can subsequently cause gastric carcinoma and peptic ulcer disease. H. pylori can survive and colonize the harsh environment of the stomach by utilizing an acid-sensing and response mechanism, the ArsRS two-component system (TCS). The histidine kinase ArsS auto-phosphorylates when exposed to an acidic pH. ArsS then phosphorylates the OmpR-related response regulator, ArsR, which when phosphorylated acts as a transcriptional regulator for a variety of genes. Prior research has shown that ArsR is an essential protein for H. pylori survival, as ΔarsR strains are not viable in the laboratory. A growing body of evidence has also shown that lysine acetylation at highly conserved lysine residues K87, K101, and K202 in OmpR-related response regulators modulates their function. This information led us to hypothesize that highly conserved lysine residues of ArsR are acetylated, affecting expression of ArsR-regulated genes. To test our hypothesis of lysine acetylation in ArsR, we conducted mass spectrometry of the ArsR-FLAG protein which confirmed the presence of lysine acetylation at lysine residue K87 in ArsR. To determine the effects of this acetylated lysine residue in ArsR, we created acetyl-mimic mutants for each of the three conserved lysine residues and quantified mRNA levels of a well-characterized ArsR up related gene, ureA at pH 7 and pH 5. We found that the mutation of these lysine residues results in an inability for ArsR to differentially regulate ureA in K87 and K101 residues in comparison to our control mutant 26695 in response to acidic conditions. Our findings along with the growing body of evidence regarding lysine acetylation in prokaryotes shows not only the evolutionary conservation of this modification but emphasizes the functional diversity prokaryotes utilize for complex cellular functions.

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