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The phenomenon of persistence in bacteria - the role of toxin-antitoxin systems.
Váchal, Martin ; Lichá, Irena (advisor) ; Seydlová, Gabriela (referee)
Most bacterial species currently studied are able to generate a small fraction of heterogeneous persister cells which are tolerant to antibiotics or other antimicrobials and still genetically identical to the susceptible parental population. Bacterial persisters emerge as a result of the stochastic regulation of cellular processes. Persistence can be triggered by stressful environmental stimuli or emerge spontaneously under favourable growth conditions. According to their origin, persistent subpopulations were divided into type I and type II persisters. Many recent studies indicate that toxin-antitoxin (TA) systems increase persistence. TA systems are ubiquitous genetic elements in prokaryotes and consist of a stable toxin, inhibiting essential cellular functions in persister cells, and an unstable antitoxin, which counteracts the activity of its toxin. Overexpression of toxin parts in excess of their corresponding antitoxin leads to multidrug tolerance (MDT). This work summarizes causes of persister formation and their hypothetical survival strategies and deals primarily with TA systems, controlling bacterial persistence of model organism Escherichia coli. The emphasis is put on the description of type I TA system TisB/IstR-1, type II TA systems HipBA, RelBE, MazEF, DinJ-YafQ, MqsRA, type V TA...
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