Thesis
Chemical regulation of two-component systems: a study of the regulation of Staphylococcus aureus two-component systems, SrrAB and ArlRS, through the effects of small molecules
University of Iowa
Master of Science (MS), University of Iowa
Summer 2021
DOI: 10.17077/etd.005956
Abstract
The healthcare community continues to contend with the deadly consequences of bacterial infections. Staphylococcus aureus (S. aureus) infections can lead to toxic shock syndrome, infective endocarditis, and necrotizing pneumonia. More concerning are the methicillin-resistant strains (MRSA) that can plague hospitals and sports locker rooms. S. aureus bacteria’s two-component systems (TCS) dynamically regulate gene expression. TCS are composed of a membrane bound histidine kinase and a partner response regulator that typically binds DNA or other proteins to affect gene expression. S. aureus possesses sixteen TCS, several of which are implicated in the promotion of virulence in this pathogen. The S. aureus TCS SrrAB is known to control the production of the TSST-1 toxin produced in toxic shock syndrome, maintain growth in the microaerobic environment produced at the site of infection, and positively regulate the production of biofilms. Another TCS, ArlRS, regulates biofilm production while also being involved in the regulation of processes such as autolysis and capsule synthesis. How these TCS are regulated is largely unknown, but their status as global regulators present them as clear targets for modulating virulence outcomes, and small molecule compounds can be a method by which these outcomes are controlled. The regulation of SrrAB, like many two component systems, is due in part to ligand binding of its extracellular Cache domain. The identity of the SrrB Cache domain ligand is unknown, but preliminary studies in the lab have identified itaconic acid as a candidate. Here we performed a structural study of the SrrB Cache domain ligand binding. In collaboration with the Horswill lab, two small molecules, 3,4’-dimethoxyflavone and homopterocarpin, were found to inhibit the expression of known ArlRS-mediated genes and processes. Here we performed a biochemical study of how these molecules affect the individual domains of the ArlRS in order to elucidate the mechanism behind this observed inhibition and provide insights into how to target this TCS. Ultimately, we determined a ligand binding site for the SrrB Cache domain and the identified a potential mechanism behind the inhibition the ArlS histidine kinase.
Details
- Title: Subtitle
- Chemical regulation of two-component systems: a study of the regulation of Staphylococcus aureus two-component systems, SrrAB and ArlRS, through the effects of small molecules
- Creators
- Diamond Jelani
- Contributors
- Ernesto J Fuentes (Advisor) - University of Iowa, Biochemistry and Molecular BiologyDaniel L Weeks (Committee Member)Dominique H Limoli (Committee Member)Maria Spies (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Biochemistry
- Date degree season
- Summer 2021
- DOI
- 10.17077/etd.005956
- Publisher
- University of Iowa
- Number of pages
- viii, 68 pages
- Copyright
- Copyright 2021 Diamond Jelani
- Language
- English
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (pages 65-68).
- Public Abstract (ETD)
S. aureus bacteria present a current health care concern as there has been rise in their antibiotic resistance over the years. This increase in antibiotic resistance has given urgency to the problem of identifying new ways to target S. aureus during an infection. One mechanism to target these bacteria is to explore how their regulatory signaling systems known as two component systems, are affected by small molecules. Two such systems, SrrAB and ArlRS have been shown to increase the virulence of S. aureus due to their roles in promoting things such as biofilm formation that increases the difficulty of delivering antibiotics to the infection site. This study examined the binding of small molecules of the sensor domain of the SrrAB TCS and the response of the active histidine kinase and response regulator proteins of the ArlRS TCS in order to better understand how these systems are regulated and identify potential strategies for their inhibition.
- Academic Unit
- Biochemistry and Molecular Biology
- Record Identifier
- 9984124171302771
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