Emily Lowry1, Yiqing Wang2, Tal Dagan2 and Amir Mitchell1 1Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA; 2Institute of General Microbiology, Kiel University, 24118 Kiel, Germany Corresponding author: amir.mitchellumassmed.edu Abstract

Colibactin produced primarily by Escherichia coli strains of the B2 phylogroup cross-links DNA and can promote colon cancer in human hosts. Here, we investigate the toxin's impact on colibactin producers and on bacteria cocultured with producing cells. Using genome-wide genetic screens and mutation accumulation experiments, we uncover the cellular pathways that mitigate colibactin damage and reveal the specific mutations it induces. We discover that although colibactin targets A/T-rich motifs, as observed in human colon cells, it induces a bacteria-unique mutation pattern. Based on this pattern, we predict that long-term colibactin exposure will culminate in a genomic bias in trinucleotide composition. We test this prediction by analyzing thousands of E. coli genomes and find that colibactin-producing strains indeed show the predicted skewness in trinucleotide composition. Our work reveals a bacteria-specific mutation pattern and suggests that the resistance protein encoded on the colibactin pathogenicity island is insufficient in preventing self-inflicted DNA damage.

Footnotes

[Supplemental material is available for this article.]

Article published online before print. Article, supplemental material, and publication date are at https://www.genome.org/cgi/doi/10.1101/gr.279517.124.

Freely available online through the Genome Research Open Access option.

Received April 26, 2024. Accepted August 14, 2024.