Toxin PezT

UniProtKB accession:  Q97QZ1

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UniProtKB description:  Toxic component of a type II toxin-antitoxin (TA) system. Phosphorylates UDP-N-acetyl-D-glucosamine (UNAG) on the 3'-hydroxyl group of the N-acetyl-D-glucosamine moiety, yielding UNAG-3P. UNAG-3P inhibits MurA, the first committed step in cell wall synthesis, which is then blocked. Upon expression in E.coli results in decreased cell growth and viability, followed 3 hours later by growth restoration; the toxic effect and phosphorylation of UNAG are neutralized by coexpression with cognate antitoxin PezA. A mutant lacking the last 11 residues is stably maintained in E.coli, unlike the wild-type which undergoes spontaneous mutation. Expression of the deletion mutant in rapidly growing liquid cultures leads to cell bulging, permeabilization and massive lysis by 1 hour. Cells that survive are not able to undergo cytokinesis. Expression in slowly growing cells leads to bulging but not lysis.