Gram negative genome.

While there is growing evidence of a potential role of gut bacteria in colorectal cancer (CRC) development, actual causation has been difficult to establish. One possible mechanism is through a genotoxic compound called colibactin that is produced by gut E. coli that specifically harbor something called a polyketide synthase (pks) island. These pks+ E. coli have been found in high proportion among CRC patients, and the colibactin they produce has been shown to cause DNA damage that could promote CRC. This interesting study goes a step further by characterizing a mutational signature of two specific types of mutations induced by colibactin in colon cells. When they queried CRC whole genome sequences, 5-10% had high pks signatures. In addition, a small subset of urinary tract and head and neck cancers also had high pks signatures. TBL: Colibactin producing, polyketide synthase+ E. coli produce a genomic signature of their plausible role in CRC development. | Pleguezuelos-Manzano, Nature 2020