8IFM

Cryo-EM structure of tetrameric SPARTA gRNA-ssDNA target complex in state 2

8IFM の概要

• エントリーDOI: 10.2210/pdb8ifm/pdb
• EMDBエントリー: 35421
• 分子名称: TIR domain-containing protein, Piwi domain-containing protein, guide RNA, ... (5 entities in total)
• 機能のキーワード: rna binding protein-rna-dna complex, rna binding protein/rna/dna
• 由来する生物種: Thermoflavifilum thermophilum; 詳細
• タンパク質・核酸の鎖数: 16
• 化学式量合計: 503703.49

構造登録者

Zhang, J.T.,Jia, N. (登録日: 2023-02-18, 公開日: 2024-01-17, 最終更新日: 2024-04-10)

主引用文献

Zhang, J.T.,Wei, X.Y.,Cui, N.,Tian, R.,Jia, N.
Target ssDNA activates the NADase activity of prokaryotic SPARTA immune system.
Nat.Chem.Biol., 20:503-511, 2024

PubMed Abstract: Argonaute proteins (Agos), which use small RNAs or DNAs as guides to recognize complementary nucleic acid targets, mediate RNA silencing in eukaryotes. In prokaryotes, Agos are involved in immunity: the short prokaryotic Ago/TIR-APAZ (SPARTA) immune system triggers cell death by degrading NAD in response to invading plasmids, but its molecular mechanisms remain unknown. Here we used cryo-electron microscopy to determine the structures of inactive monomeric and active tetrameric Crenotalea thermophila SPARTA complexes, revealing mechanisms underlying SPARTA assembly, RNA-guided recognition of target single-stranded DNA (ssDNA) and subsequent SPARTA tetramerization, as well as tetramerization-dependent NADase activation. The small RNA guides Ago to recognize its ssDNA target, inducing SPARTA tetramerization via both Ago- and TIR-mediated interactions and resulting in a two-stranded, parallel, head-to-tail TIR rearrangement primed for NAD hydrolysis. Our findings thus identify the molecular basis for target ssDNA-mediated SPARTA activation, which will facilitate the development of SPARTA-based biotechnological tools.

PubMed: 37932528
DOI: 10.1038/s41589-023-01479-z

実験手法

ELECTRON MICROSCOPY (2.92 Å)