COMMUNICATION BETWEEN PHAGES LEADS TO NCRNA-MEDIATED LYSIS-LYSOGENY DECISIONS

Upon the infection of a host cell, a temperate phage is able to choose between two pathways, the lytic pathway and the lysogenic one. In a previous study, we showed that Bacillus phages use peptide-based communication to regulate the lysis-lysogeny decision. The phage genetic system enabling this communication, called arbitrium, is encoded by 3 genes: aimP, which produces a secreted communication peptide; aimR, the intracellular peptide receptor; and aimX, a non-coding RNA that executes the downstream lysogeny decision. The expression of AimX is regulated by the peptide-receptor interaction, but so far the molecular mechanism by which AimX executes the lysogeny decision was unknown. Here we demonstrate, using an arbitrium-encoding phage that infects Bacillus cereus, that AimX expression directly controls the phage CI repressor (the master regulator of lysogeny) using an antisense mechanism. We further show evidence that the vast majority of arbitrium-containing phages use such antisense regulation to execute the peptide-based communication decisions.