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Toxins 2014, 6(9), 2787-2803;

Toxin ζ Reversible Induces Dormancy and Reduces the UDP-N-Acetylglucosamine Pool as One of the Protective Responses to Cope with Stress

Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, C/Darwin 3, Madrid 28049, Spain
Author to whom correspondence should be addressed.
Received: 18 June 2014 / Revised: 14 August 2014 / Accepted: 9 September 2014 / Published: 18 September 2014
(This article belongs to the Special Issue Toxin-Antitoxin System)
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Toxins of the ζ/PezT family, found in the genome of major human pathogens, phosphorylate the peptidoglycan precursor uridine diphosphate-N-acetylglucosamine (UNAG) leading to unreactive UNAG-3P. Transient over-expression of a PezT variant impairs cell wall biosynthesis and triggers autolysis in Escherichia coli. Conversely, physiological levels of ζ reversibly induce dormancy produce a sub-fraction of membrane-compromised cells, and a minor subpopulation of Bacillus subtilis cells become tolerant of toxin action. We report here that purified ζ is a strong UNAG-dependent ATPase, being GTP a lower competitor. In vitro, ζ toxin phosphorylates a fraction of UNAG. In vivo, ζ-mediated inactivation of UNAG by phosphorylation does not deplete the active UNAG pool, because expression of the toxin enhances the efficacy of genuine cell wall inhibitors (fosfomycin, vancomycin or ampicillin). Transient ζ expression together with fosfomycin treatment halt cell proliferation, but ε2 antitoxin expression facilitates the exit of ζ-induced dormancy, suggesting that there is sufficient UNAG for growth. We propose that ζ induces diverse cellular responses to cope with stress, being the reduction of the UNAG pool one among them. If the action of ζ is not inhibited, e.g., by de novo ε2 antitoxin synthesis, the toxin markedly enhances the efficacy of antimicrobial treatment without massive autolysis in Firmicutes. View Full-Text
Keywords: toxin-antitoxin system; fosfomycin; vancomycin; ampicillin; bacterial persistence toxin-antitoxin system; fosfomycin; vancomycin; ampicillin; bacterial persistence

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Tabone, M.; Ayora, S.; Alonso, J.C. Toxin ζ Reversible Induces Dormancy and Reduces the UDP-N-Acetylglucosamine Pool as One of the Protective Responses to Cope with Stress. Toxins 2014, 6, 2787-2803.

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