Antagonistic interactions between phage and host factors control arbitrium lysis-lysogeny decision

Area of Science:

• Microbiology
• Molecular Biology
• Virology

Background:

• Bacteriophages (phages) employ communication systems, such as the arbitrium system, to regulate their life cycle decisions.
• The precise molecular mechanisms by which phages coordinate lysis-lysogeny decisions remain largely unknown.
• Bacterial toxin-antitoxin systems, like MazE-MazF, are crucial for cellular processes and can be targets for phage manipulation.

Purpose of the Study:

• To elucidate the mechanism by which the arbitrium system in Bacillus subtilis phage phi3T regulates the lysis-lysogeny decision.
• To investigate the interaction between the phage arbitrium system and the bacterial MazE-MazF toxin-antitoxin system.
• To understand the evolutionary strategy employed by phages in controlling their life cycle.

Main Methods:

• Investigated the interaction between phage proteins (AimX, YosL, phi3T_93, AimP) and bacterial toxin-antitoxin components (MazE, MazF).
• Utilized molecular biology techniques to analyze the modulation of MazF activity and MazE-MazF complex formation.
• Studied the role of phage antiterminator AimR and its regulation by AimP in controlling phage gene expression.

Main Results:

• Phage phi3T proteins AimX and YosL directly bind and inactivate the bacterial toxin MazF.
• AimX also inhibits phi3T_93, a protein that promotes lysogeny by interacting with MazE.
• Accumulation of phage peptide AimP leads to inactivation of AimR, ceasing aimX expression and promoting lysogeny by allowing MazF activity.

Conclusions:

• The arbitrium system in phage phi3T hijacks the bacterial MazE-MazF toxin-antitoxin system to control lysis-lysogeny decisions.
• Phage strategy involves initially promoting lysis through MazF inactivation and later enabling lysogeny via AimP-mediated regulation.
• This study reveals an evolutionary mechanism where phages adapt bacterial defense systems for their own life cycle regulation.