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Volume 163, Issue 3, March 2017
- Many bacterial persister cells survive antibiotics by expressing toxin-antitoxin proteins that regulate cell growth and division. Surprisingly little is known about how these proteins affect cellular structures. Using a combination of electron and light microscopy, we visualized the effects of MazEF toxin-antoxin proteins in E. coli persister cells exposed to three different antibiotics. During persister formation, their chromosomes were condensed and their ribosomes were excluded from their nucleoids. After ciprofloxacin exposure, persisters regrew into extremely long cells, which subsequently divided during stationary growth phase. This extreme filamentation was unique to ciprofloxacin, likely caused by its inhibition of cell division during regrowth.