Colibactin is as mall molecule produced by certain bacterial species of the human microbiota that harbour the pks genomic island. Pks + bacteria induce agenotoxic phenotype in eukaryotic cells and have been linked with colorectal cancer progression. Colibactin is produced in abenign, prodrug form which,p rior to export, is enzymatically matured by the producing bacteria to its active form. Although the complete structure of colibactin has not been determined, key structural features have been described including an electrophilic cyclopropane motif,w hich is believed to alkylate DNA. To investigate the influence of the putative "warhead" and the prodrug strategy on genotoxicity,as eries of photolabile colibactin probes were prepared that upon irradiation induced apks + like phenotype in HeLa cells.Furthermore,results from DNAcross-linking and imaging studies of clickable analogues enforce the hypothesis that colibactin effects its genotoxicity by directly targeting DNA.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.