SIR2-mediated filament assembly activates the NLR-like protein Avs5 for bacterial antiviral defense.

ATP-bound Avs5 is monomeric, then forms SIR2-mediated dimers and ATP-dependent filaments that are required for efficient NAD+ hydrolysis and antiphage defense.

• Why it matters: Bacterial NLR-like antiviral defense is linked to higher-order assembly, but how Avs5 couples receptor activation to NADase effector function was unclear.
• What they did: The authors used structure-guided mutagenesis, biochemical assays, and functional antiphage analyses to test whether SIR2-mediated filament assembly controls ATP-dependent NAD+ hydrolysis.
• The result: Filament assembly is required for efficient NAD+ hydrolysis and antiphage defense, supporting an effector-driven activation mechanism in Avs5.