A compact Druantia defense clears phage infections via single-stranded DNA recognition and directional duplex unwinding.

The compact type III-A Druantia system recognizes exposed single-stranded DNA to clear phages via directional duplex unwinding.

• Why it matters: Understanding bacterial defense mechanisms against phages is crucial for insights into microbial immunity and potential biotechnological applications.
• What they did: Researchers used Escherichia coli models to demonstrate that DruE and DruH proteins clear restriction-sensitive or recombination-prone phages without harming host cell growth, with DruE unwinding DNA in a 3'-to-5' direction.
• The result: The findings suggest that exposed single-stranded DNA triggers bacterial immunity through the helicase activity of Druantia, enabling phage clearance without affecting bacterial viability.