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| Title | Identification and structure determination of a type III-Bv CRISPR complex that post-translationally modifies an associated toxin. |
|---|---|
| Journal, issue, pages | Structure, Year 2026 |
| Publish date | Jul 1, 2026 |
Authors | Shishir Pandey / Nathaniel Burman / William S Henriques / Tanner Wiegand / Trevor Zahl / Hannah Nyquist / Tanner Spreeuw / Murat Buyukyoruk / Blake Wiedenheft / ![]() |
| PubMed Abstract | Cas7-family proteins form the scaffolds of multi-subunit CRISPR RNA-guided surveillance complexes. To explore how Cas7 diversification expands CRISPR function, we identified Cas7 fusion proteins ...Cas7-family proteins form the scaffolds of multi-subunit CRISPR RNA-guided surveillance complexes. To explore how Cas7 diversification expands CRISPR function, we identified Cas7 fusion proteins linked to diverse accessory domains, including a type III-B variant (III-Bv) in which a Cas7 homolog (Cmr1) is fused to the MntA antitoxin and encoded adjacent to a HEPN-family toxin. Structures reveal that the core Cas proteins assemble into a stable surveillance complex in the absence of crRNA, whereas incorporation of the Cmr1-MntA fusion is crRNA-dependent. Target RNA recognition triggers conformational changes that expose the Cas10 cyclase active site and promote cyclic oligoadenylate synthesis. Biochemical analyses show that the CRISPR-associated MntA is enzymatically active and AMPylates the associated HEPN protein. Together, these findings establish the structural basis for assembly of a type III-Bv surveillance complex containing an enzymatically active toxin-antitoxin module. |
External links | Structure / PubMed:42385699 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 2.9 - 3.0 Å |
| Structure data | EMDB-73877, PDB-9z7q: EMDB-73882, PDB-9z7v: EMDB-73883, PDB-9z7x: |
| Chemicals | ![]() ChemComp-ZN: ![]() ChemComp-HOH: |
| Source |
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Keywords | IMMUNE SYSTEM/RNA / CRISPR / complex / crRNA / IMMUNE SYSTEM / IMMUNE SYSTEM-RNA complex / target / RNA |
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dissulfurispira thermophila (bacteria)
escherichia phage ms2 (virus)
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