Filament assembly powers NbaSPARDA in bacterial defense

Abstract

The SPARDA system, a short Argonaute-based bacterial defense mechanism, employs guide RNA to recognize invading complementary DNA and degrade both invader and the host genome, leading to cell death or dormancy. A recent paper published in Cell Research elucidated the activation mechanism of Novosphingopyxis baekryungensis NbaSPARDA by capturing cryo-EM snapshots, demonstrating that guide RNA–target DNA heteroduplex formation triggers filament assembly and subsequent activation of collateral nuclease activity on environmental nucleic acids.