Type II toxin-antitoxin (TA) systems are composed of a stable toxin and its cognate unstable antitoxin that impedes the toxin through direct interaction. The human oral pathogen Streptococcus mutans uses a quorum-sensing peptide (CSP) as a stress-inducible pheromone to synchronize gene expression in response to specific stressors. The objectives of this study were to investigate the role of S. mutans MazEF TA in cell survival and characterize the functionality of CSP-inducible chromosomal type II TAs. Our results suggest that MazEF represents a stress-response element. Interestingly, S. mutans negatively regulates its MazEF system under high-cell-density environment that is characteristic of oral biofilms. S. mutans also encodes a novel chromosomal type II TA involved in biofilm formation and development of dormant persister cells. The results from this study suggest a complex interplay between quorum-sensing (signal), type II TA activation (response), and persister formation (phenotype) as a reaction to environmental perturbations.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/43128 |
| Date | 05 December 2013 |
| Creators | Mankovskaia, Alexandra |
| Contributors | Lévesque, Céline |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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