Graduation Semester and Year
Spring 2024
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Quantitative Biology
Department
Biology
First Advisor
Cara Boutte
Second Advisor
Todd Castoe
Third Advisor
Melissa Walsh
Fourth Advisor
Joseph Boll
Fifth Advisor
Mark Pellegrino
Abstract
Mycobacteria encompass many pathogenic species known to cause severe disease in humans. A well-known example is Mycobacterium tuberculosis (Mtb), the causative agent of the lung disease tuberculosis, which kills millions of humans worldwide yearly. Pathogenic mycobacteria like Mtb are challenging to treat because of their innate ability to adapt to environmental stress. Their unique cell physiology and conserved stress responses allow them to combat biological insults, regulate growth, and regulate genes involved in stress; all these responses increase tolerance to antibiotics. The current therapies to treat mycobacterial infections are lengthy and, at times, unsuccessful, partly due to antibiotic tolerance. A better understanding of mycobacteria cell physiology and stress response will promote the development of better treatments for chronic and recurring antibiotic-tolerant infections. Here, our work focuses on three important aspects of mycobacterial cell biology often associated with survival and antibiotic tolerance: the stringent response (a conserved stress response in bacteria), biofilm formation, and cell wall regulation. We used Mycobacterium abscessus (Mab), a pathogen that causes soft tissue and respiratory infections, for stringent response and biofilm studies. We found that media composition affects the structure and composition of Mab biofilms, and the susceptibility of planktonic cells to antibiotics. In addition, we also discovered that Mab's stringent response pathway uses a non-canonical alarmone synthesis pathway. To study cell wall regulation, we used Mycobacterium smegmatis, a fast-growing non-pathogenic species commonly used to study the Mycobacterium genus. We focused on investigating the relationship between two essential growth proteins, CwlM and MurA, which are involved in the metabolism of the peptidoglycan layer, the primary layer in mycobacteria that provides shape and rigidity. We found that the ix interaction between MurA (the enzyme) and CwlM (its regulator) is transient. We also identified the likely interaction site between CwlM and MurA, which affects the production of precursors by MurA. In addition, we investigated the survival and cell physiology of interaction site mutants, which shed light into understanding the role of CwlM's regulation of MurA during mycobacterial growth.
Keywords
Mycobacteria, cell wall, peptidoglycan, stress response, biofilms, mycobacterium abscessus, mycobacterium smegmatis, mycobacterium tuberculosis, antibiotic tolerance, gene regulation, phosphorylation
Disciplines
Amino Acids, Peptides, and Proteins | Bacteria | Bacterial Infections and Mycoses | Bacteriology | Enzymes and Coenzymes | Epidemiology | Integrative Biology | Lipids | Microbial Physiology | Molecular Genetics | Pathogenic Microbiology
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Hunt Serracin, Augusto C., "Managing Stress: A Study of Stress Response Mechanisms in Mycobacteria" (2024). Biology Dissertations. 5.
https://mavmatrix.uta.edu/biology_dissertations/5
Included in
Amino Acids, Peptides, and Proteins Commons, Bacteria Commons, Bacterial Infections and Mycoses Commons, Bacteriology Commons, Enzymes and Coenzymes Commons, Epidemiology Commons, Integrative Biology Commons, Lipids Commons, Microbial Physiology Commons, Molecular Genetics Commons, Pathogenic Microbiology Commons