Bacteria phage cooperation during mammalian infection

Most bacterial pathogens carry multiple prophages (and phage-derived elements) within their genome, some of which can turn into deadly particles under stress. These prophages must adapt to the pathogenic life-style of their host to support their mutual survival within the mammalian niche. Listeria monocytogenes 10403S harbors two phage elements in its chromosome; one active producing infective virions and the other cryptic producing phage tail-like bacteriocins, each capable of triggering bacterial lysis under stress. We recently found that the two phage elements are fully coordinated and perfectly adapted to Lm infection of mammalian cells. Further we uncovered that the cryptic element, which is more ancient, controls the induction of the active prophage, regulating its activity as a virulence-associated molecular switch. This study presents the characterization of an inter-phage cross-regulatory interaction that coordinates the lytic production of co-habiting phage elements. The results provide a molecular insight into the phenomenon of polylysogeny and its intricate adaptation to complex environments.