Doctoral Dissertations
Date of Award
5-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Chemistry
Major Professor
Tessa R. Calhoun
Committee Members
Jennifer L. Morrell-Falvey, Fred A. Heberle, Thanh D. Do
Abstract
A molecule's entry into a cell is impeded primarily at the surface of Gram-positive bacteria. This interface serves as the boundary separating cellular contents from the external environment and is composed of a thick layer of peptidoglycan and a lipid bilayer equipped with protein and lipid species with various roles including that of small-molecule transport. As such, understanding these molecule-membrane interactions is imperative to examine in order to design novel drugs or adjuvants to combat the global antibiotic resistance predicament. Knowledge regarding passive diffusion and overall organization of small molecules in the lipid bilayer of living Gram-positive cells is limited as the complexity of this system is not as commonly studied as Gram-negative and eukaryotic species. This dissertation broadly aims to quantify interactions of small amphiphilic molecules with the membrane of living Staphylococcus aureus and Bacillus subtilis cells by using second harmonic scattering (SHS) techniques. SHS is uniquely qualified to study these phenomena due to being inherently sensitive to surface-bound molecule orientations. First, SHS is employed in a systematic study of how the structure of both the molecule-of-interest and the membrane influence the initial adsorption to and time-resolved dynamics of amphiphilic probe molecules within living bacterial membranes. To better understand the origin of SHS signals from this study, angular distribution of these molecules are extracted by leveraging polarization resolved SHS. Lastly, these techniques are employed to study a small molecule drug system in order to understand its perturbation of membrane properties and transport.
Recommended Citation
Blake, Marea J., "Investigating Small Molecule Behavior in Living Bacterial Membranes with Second Harmonic Scattering. " PhD diss., University of Tennessee, 2024.
https://trace.tennessee.edu/utk_graddiss/10097