E. coli eliminates competitors by awakening dormant viruses in them

(ORDO NEWS) — Colibactin, which is produced by E. coli cells, activates the prophages of neighboring bacteria – viruses hidden in their own DNA.

E. coli ( Escherichia coli ) is a very common type of bacteria that inhabits the intestines of most people. As a rule, they do not bring any particular benefit or great harm to the body.

However, some strains can become dangerous under certain circumstances. In particular, some of them are able to produce colibactin , a short chain of amino acids that can cross-link the DNA of host cells, increasing the risk of bowel cancer.

Apparently, this action of colibactin is just a “side effect”: E. coli itself uses this toxin to fight bacterial competitors.

Their cells often carry latent viruses that remain dormant, waiting for the right moment. The appearance of colibactin in the environment triggers the activity of these viruses, and many neighbors of E. coli are not up to competition.

Viruses that infect bacteria are called phages. Some of them can integrate their DNA into the genome of the host cell, or simply leave it until better times in his cell.

Such genetic fragments are called prophages , and they are usually activated when the cell is having difficulty replicating and finding a new host. DNA damage by colibactin turned out to be one such factor.

In response to it, the bacterium urgently launches the mechanisms of repair, “repair” of the genome, and the phages “wake up”.

However, for most of the neighbors of E. coli, colibactin is not so dangerous. The experiments of scientists have shown that many of them use the mechanisms of protection against this toxin.

And even if it is not there, colibactin is not very stable, and most of its molecules break down before they can cause irreparable damage to DNA. Only a few cells are at risk – those that contain prophages and are in close proximity to E. coli, which synthesizes it.


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