Acinetobacter baumannii is an increasingly multidrug-resistant pathogen contributing to hospital-acquired infections, necessitating a greater understanding of how it interacts with its surroundings. Many bacteria utilize different methods of bacterial motility to move about and interact with these surroundings. A bacterial second messenger, cyclic diguanosine monophosphate (c-di-GMP), can regulate various motility factors that are potentially advantageous for survival in and adaptation to their environment. Concentrations of c-di-GMP are regulated by specific synthesizing and degrading enzymes. Controlled levels of c-di-GMP allow interaction between the c-di-GMP and its binding effectors that induce changes in bacterial phenotypes such as biofilm formation and motility. A search of the A. baumannii genome identified two proteins that contain the c-di-GMP-binding PilZ domain. The PilZ protein for which this PilZ domain was named was initially discovered in Pseudomonas aeruginosa where it has been demonstrated to be a part of the type IV pilus machinery. Type IV pili play roles in twitching motility, adhering to surfaces, DNA uptake, protein secretion, and predation. One of the PilZ-containing proteins from A. baumannii resembled this original PilZ protein (PilZ), while the second PilZ-containing protein contained a hydrolase domain with unknown substrate specificity (HydP). I investigated whether these PilZ-containing proteins play a role in motility of A. baumannii by testing two strains: AB5075 that displays twitching motility, and ATCC17978 that displays an uncharacterized form of surface-associated motility. Results suggest PilZ plays a role in twitching motility, while its effect on surface-associated motility phenotypes3 is possibly due to polar effects from mutation. Results also suggest HydP plays a role in surface-associated motility, although its mechanism is not understood. Testing of both proteins’ PilZ domains indicates they may not bind c-di-GMP, implying they may be playing roles in motility regulation through other mechanisms outside of binding c-di-GMP. These findings give us greater insight into the regulatory mechanisms used by A. baumannii to move about its environment.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:etd-5974 |
| Date | 01 August 2024 |
| Creators | Smith, Gabriel |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Electronic Theses and Dissertations |
| Rights | Copyright by the authors. |
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