Bacteria sense virus-induced genome degradation via methylated mononucleotides

Area of Science:

• Bacteriology
• Virology
• Molecular Biology
• Genetics

Background:

• Bacteriophages (phages) pose a significant threat to bacterial populations.
• Phages often degrade the host bacterial genome during infection.
• Existing bacterial defense mechanisms have limitations in addressing genome degradation.

Purpose of the Study:

• To identify and characterize a novel bacterial defense system against phage infection.
• To elucidate the mechanism by which bacteria detect and respond to phage-induced host genome degradation.
• To understand how phages may evade this newly discovered defense system.

Main Methods:

• Genome sequencing and analysis of bacterial defense systems.
• Biochemical assays to detect modified nucleotides.
• Genetic manipulation of bacterial and phage genomes.
• Infection assays to measure phage propagation and bacterial survival.

Main Results:

• Discovery of Metis, a bacterial defense system that senses phage-mediated host genome degradation.
• Identification of modified mono-nucleotide m⁶dAMP as the signal for host genome breakdown.
• Characterization of two types of Metis systems (Type I and Type II) with distinct effector mechanisms.
• Demonstration that Metis efficacy relies on endogenous DNA methylases.
• Identification of phage mutations that inactivate host genome degradation as an escape strategy.

Conclusions:

• Metis represents a novel bacterial defense strategy directly targeting phage-induced host genome degradation.
• The detection of m⁶dAMP serves as a crucial alarm signal for bacterial cells.
• Understanding Metis and phage counter-defense mechanisms provides insights into host-pathogen interactions and potential biotechnological applications.