Download MendeleyTetramerization-dependent activation of the Sir2-associated short prokaryotic Argonaute immune system.
Cui, N., Zhang, J.T., Li, Z., Wei, X.Y., Wang, J., Jia, N.(2024) Nat Commun 15: 8610-8610
- PubMed: 39366953
- DOI: https://doi.org/10.1038/s41467-024-52910-5
- Primary Citation of Related Structures:
8Y7Z, 8Y80, 8Y82 - PubMed Abstract:
Eukaryotic Argonaute proteins (eAgos) utilize short nucleic acid guides to target complementary sequences for RNA silencing, while prokaryotic Agos (pAgos) provide immunity against invading plasmids or bacteriophages. The Sir2-domain associated short pAgo (SPARSA) immune system defends against invaders by depleting NAD + and triggering cell death. However, the molecular mechanism underlying SPARSA activation remains unknown. Here, we present cryo-EM structures of inactive monomeric, active tetrameric and active NAD + -bound tetrameric SPARSA complexes, elucidating mechanisms underlying SPARSA assembly, guide RNA preference, target ssDNA-triggered SPARSA tetramerization, and tetrameric-dependent NADase activation. Short pAgos form heterodimers with Sir2-APAZ, favoring short guide RNA with a 5'-AU from ColE-like plasmids. RNA-guided recognition of the target ssDNA triggers SPARSA tetramerization via pAgo- and Sir2-mediated interactions. The resulting tetrameric Sir2 rearrangement aligns catalytic residue H186 for NAD + hydrolysis. These insights advance our understanding of Sir2-domain associated pAgos immune systems and should facilitate the development of a short pAgo-associated biotechnological toolbox.
Organizational Affiliation:
Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China.
