Peptidoglycan (PG) is an essential cell-wall biopolymer in virtually all bacteria. It is composed of glycan strands of N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc) crosslinked by peptide chains of alternating D- and L- amino acids and diamines. PG plays an important role in 1) cell elongation and division, 2) cell strength and morphology, 3) antibiotic susceptibility, and 4) host immune detection and modulation. While differences in peptide chains are common, deviations in glycan strand composition were not previously known to occur. Here, we provide characterization of the first known deviation to bacterial glycan strand composition — GlcNAc-GlcNAc-anhMurNAc (G-G- anhM) in Borrelia burgdorferi, the causative agent of Lyme disease. B. burgdorferi with less G-G-anhM were found to be significantly less motile, flexible, and stress-tolerant while possessing gross morphological defects and less overall PG. Our studies also characterized the muropeptide profile of Borrelia afzelii, Borrelia garinii, and Borrelia hermsii — species of Borrelia associated with causing different disease manifestations of Lyme disease, and relapsing fever, respectively. These species were found to incorporate appreciable amounts of G-G-anhM into their PG, suggesting an evolutionary adaptation to life inside a tick that predates the differentiation of Lyme disease and relapsing fever Borrelia. Finally, we provide partial characterization of a putative penicillin-binding protein in B. burgdorferi — a class of highly conserved PG synthesis enzymes present in the vast majority of bacteria. Collectively, the work in this thesis furthers our understanding of the structure, function, and synthesis of PG in Borrelia. / Master of Science in Life Sciences / Peptidoglycan (PG) is the main cell-wall component in the vast majority of bacteria. PG is composed of strong, rigid sugars linked together by short, flexible amino acid chains, and resembles a mesh-like bag that surrounds the cell. In nearly all bacteria that have PG, it plays an important role in how 1) the cell grows and divides, 2) the cell dictates its shape, 3) antibiotics treat bacterial infections, and 4) the human body detects and responds to a bacterial infection. While the amino acids that make up PG are known to differ between bacterial species, deviations in sugar organization are not known to occur. Here, we characterize the first known deviation to sugar organization in bacterial PG in Borrelia burgdorferi — the bacteria that causes Lyme disease. B. burgdorferi with less of this deviation possess defects absent in their normal counterparts. In addition, we show that other Borrelia species that cause a variety of different diseases around the world mimic this sugar deviation, suggesting the majority, if not all, of Borrelia may do so. Finally, we provide partial characterization of the function of an enzyme thought to synthesize PG in B. burgdorferi. Collectively, the work in this thesis furthers our understanding of the structure, function, and synthesis of PG in Borrelia.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/112700 |
| Date | 03 June 2021 |
| Creators | DeHart, Tanner Gage |
| Contributors | Biochemistry, Jutras, Brandon L., Helm, Richard F., Sobrado, Pablo |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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