Colibactin-induced damage in bacteria is cell contact independent

Area of Science:

• Microbiology
• Genotoxicology
• Bacterial Pathogenesis

Background:

• Colibactin is a bacterial toxin produced by Escherichia coli linked to colorectal cancer.
• It causes DNA damage in mammalian cells, but its effects and delivery mechanisms in bacteria are less understood.
• Previous hypotheses suggested cell-cell contact is essential for colibactin delivery.

Purpose of the Study:

• To investigate colibactin's DNA-damaging effects on neighboring bacteria.
• To directly test the necessity of cell-cell contact for colibactin toxicity in E. coli.
• To analyze the spatial dynamics of DNA damage response to colibactin.

Main Methods:

• Utilized a fluorescent transcriptional reporter system in E. coli cultures.
• Monitored the spatiotemporal dynamics of DNA damage response.
• Conducted experiments with separated producer and reporter bacterial colonies.

Main Results:

• Colibactin-induced DNA damage was detectable in reporter cells hundreds of microns away from producers.
• DNA damage saturated within 12 hours in mixed-cell populations.
• Damage intensity decayed similarly with distance, irrespective of colony contact.

Conclusions:

• Cell-cell contact is not required for colibactin delivery and toxicity in bacteria.
• The findings suggest re-evaluating the role of contact dependence in colibactin's effects on mammalian cells.
• This study clarifies colibactin's mechanism of action in bacterial systems.