Search

Arbitrium-coding phages use peptides to communicate and coordinate the decision between lysis and lysogeny. However, the mechanism by which these phages establish lysogeny remains unknown. Here, focusing on the SPbeta phage family's model phages phi3T and SPβ, we report that a six-gene operon called the "SPbeta phages repressor operon" (sro) expresses not one but two master repressors, SroE and SroF, the latter of which folds like a classical phage integrase. To promote lysogeny, these repressors bind to multiple sites in the phage genome. SroD serves as an auxiliary repressor that, with SroEF, forms the repression module necessary for lysogeny establishment and maintenance. Additionally, the proteins SroABC within the operon are proposed to constitute the transducer module, connecting the arbitrium communication system to the activity of the repression module. Overall, this research sheds light on the intricate and specialized repression system employed by arbitrium SPβ-like phages in making lysis-lysogeny decisions. [Display omitted] • SPbeta phages encode two master repressors, SroF and SroE, in the sro operon • Multiple SroF binding sites required for repression and maintenance of lysogeny • The sro operon consists of conserved repressor and variable transducer modules • The transducer module bridges the arbitrium signal to the repression module SPbeta Bacillus phages use arbitrium to coordinate lysis-lysogeny decisions via the sro operon. Brady et al. show that the operon encodes two master repressors that bind multiple sites of the phage genome to promote lysogeny. Three accessory proteins connecting the arbitrium signal to the repression module constitute the transducer module. [ABSTRACT FROM AUTHOR]