Colibactin leads to a bacteria-specific mutation pattern and self-inflicted DNA damage

Area of Science:

• Microbiology
• Genomics
• Cancer Research

Background:

• Colibactin, produced by Escherichia coli, is a genotoxin that cross-links DNA and is linked to colon cancer.
• Understanding the effects of colibactin on the producing bacteria themselves is crucial for comprehending its overall impact.

Purpose of the Study:

• To investigate the cellular pathways that mitigate colibactin-induced DNA damage in E. coli.
• To identify the specific mutation patterns induced by colibactin within bacterial genomes.
• To determine if colibactin exposure leads to a genomic bias in trinucleotide composition in E. coli.

Main Methods:

• Genome-wide genetic screens were employed to identify bacterial resistance mechanisms.
• Mutation accumulation experiments were conducted to observe colibactin-induced mutations.
• Analysis of thousands of E. coli genomes was performed to assess trinucleotide composition biases.

Main Results:

• Colibactin targets A/T-rich motifs, similar to its effect in human cells, but induces a unique bacterial mutation pattern.
• A genomic bias in trinucleotide composition was observed in colibactin-producing E. coli strains.
• The resistance protein on the colibactin pathogenicity island appears insufficient to fully prevent self-inflicted DNA damage.

Conclusions:

• Colibactin induces bacteria-specific DNA damage and mutation patterns.
• Long-term colibactin exposure results in a predictable genomic skewness in trinucleotide composition.
• Bacterial defense mechanisms against colibactin are not entirely effective, leading to ongoing genomic alterations.