Single-cell evidence for plasmid addiction mediated by toxin–antitoxin systems

Abstract Toxin–antitoxin (TA) systems are small selfish genetic modules that increase vertical stability of their replicons. They have long been thought to stabilize plasmids by killing cells that fail to inherit a plasmid copy through a phenomenon called post-segregational killing (PSK) or addictio...

Full description

Saved in:
Bibliographic Details
Published in:Nucleic acids research 2024-02, Vol.52 (4), p.1847-1859
Main Authors: Fraikin, Nathan, Van Melderen, Laurence
Format: Article
Language:English
Subjects:
Bacteria - genetics
Bacterial Toxins - genetics
Bacterial Toxins - metabolism
Molecular Biology
Plasmids - genetics
Toxin-Antitoxin Systems
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Abstract Toxin–antitoxin (TA) systems are small selfish genetic modules that increase vertical stability of their replicons. They have long been thought to stabilize plasmids by killing cells that fail to inherit a plasmid copy through a phenomenon called post-segregational killing (PSK) or addiction. While this model has been widely accepted, no direct observation of PSK was reported in the literature. Here, we devised a system that enables visualization of plasmid loss and PSK at the single-cell level using meganuclease-driven plasmid curing. Using the ccd system, we show that cells deprived of a ccd-encoding plasmid show hallmarks of DNA damage, i.e. filamentation and induction of the SOS response. Activation of ccd triggered cell death in most plasmid-free segregants, although some intoxicated cells were able to resume growth, showing that PSK-induced damage can be repaired in a SOS-dependent manner. Damage induced by ccd activates resident lambdoid prophages, which potentiate the killing effect of ccd. The loss of a model plasmid containing TA systems encoding toxins presenting various molecular mechanisms induced different morphological changes, growth arrest and loss of viability. Our experimental setup enables further studies of TA-induced phenotypes and suggests that PSK is a general mechanism for plasmid stabilization by TA systems. Graphical Abstract Graphical Abstract
ISSN:0305-1048
1362-4962
DOI:10.1093/nar/gkae018