Widespread utilization of peptide communication in phages infecting soil and pathogenic bacteria

When temperate phages infect their host bacteria they need to choose between the lytic and lysogenic pathways. It was recently shown that phages of the SPbeta group, infecting Bacillus subtilis, utilize a peptide-based communication system called arbitrium to coordinate the lysogeny decision. In this study we show that the previously described arbitrium system represents only a small subset of a wide array of peptide-based communication systems utilized by phages for lysogeny decisions. These arbitrium-like systems show diverse peptide codes and can be detected in numerous, genetically distant phage types and conjugative elements. The pathogens Bacillus anthracis, Bacillus cereus and Bacillus thuringiensis are commonly infected by arbitrium-carrying mobile elements, which often carry toxins essential for pathogenicity. Experiments with phages containing these arbitrium-like systems demonstrate their involvement in lysogeny decisions. Finally, our results suggest that the peptide-based decision is executed by an antisense RNA that controls the regulator of the lysogenic state.