Balwina Koopal

Keywords prokaryotic immunity host defense Argonaute Cas4 pAgo nuclease PD-(D/E)xK cyanobacteria Introduction Argonaute proteins (Agos) are present in all domains of life.1 Eukaryotic Argonautes (eAgos) are the key component of the RNA-induced silencing complex (RISC) in which eAgos use guide RNAs to target complementary RNA targets.2,3,4 As such, eAgos regulate gene expression, interfere with viral RNA, and silence transposon activity.

Abstract In both prokaryotic and eukaryotic innate immune systems, TIR domains function as NADases that degrade the key metabolite NAD+ or generate signaling molecules. Catalytic activation of TIR domains requires oligomerization, but how this is achieved varies in distinct immune systems. In the Short prokaryotic Argonaute (pAgo)/TIR-APAZ (SPARTA) immune system, TIR NADase activity is triggered upon guide RNA-mediated recognition of invading DNA by an unknown mechanism.

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