THE ABUNDANCE AND DIVERSITY OF THE ARBITRIUM BACTERIOPHAGE COMMUNICATION SYSTEM

Upon infection of a bacterial cell, a temperate bacteriophage can either lyse the host cell or integrate into its genome. We have recently discovered a novel phage communication system, named “arbitrium”, which guides the lysis-lysogeny decision during infection. The arbitrium system is based on small peptides, released during each infection cycle. Upon accumulation of the peptide to a high enough concentration, the phage decides to lysogenize. While the function and mechanism of the arbitrium system have been demonstrated, the abundance of the system in nature has not been fully elucidated.

We performed extensive searches for distant homologs of the arbitrium system and revealed a wide array of arbitrium-like systems in conjugative elements and phages infecting soil Bacilli. We found that the arbitrium system that we have previously described represents just one clade out of 11 groups. Each of these groups exhibits a different peptide communication code. We found the arbitrium systems in more than 10 different types of phages and commonly near an integrase gene, suggesting that a wide array of phages use arbitrium for lysogeny decisions. Experiments with two phages containing distant arbitrium systems demonstrate the effect of the arbitrium peptide during infection.