9Z7Q

Cryo-EM Structure of the Type III-Bv CRISPR Complex from Dissulfurispira thermophila bound to a crRNA

Summary for 9Z7Q

• Entry DOI: 10.2210/pdb9z7q/pdb
• EMDB information: 73877
• Descriptor: Type III-B CRISPR-associated protein Cas10/Cmr2, Type III-B CRISPR module-associated protein Cmr3, Type III-B CRISPR module RAMP protein Cmr4, ... (8 entities in total)
• Functional Keywords: crispr, complex, crrna, immune system, immune system-rna complex, immune system/rna
• Biological source: Dissulfurispira thermophila; More
• Total number of polymer chains: 10
• Total formula weight: 351653.93

Authors

Burman, N.,Pandey, S.,Wiedenheft, B. (deposition date: 2025-11-17, release date: 2026-07-15)

Primary citation

Pandey, S.,Burman, N.,Henriques, W.S.,Wiegand, T.,Zahl, T.,Nyquist, H.,Spreeuw, T.,Buyukyoruk, M.,Wiedenheft, B.
Identification and structure determination of a type III-Bv CRISPR complex that post-translationally modifies an associated toxin.
Structure, 2026

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 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.

PubMed: 42385699
DOI: 10.1016/j.str.2026.06.002

Experimental method

ELECTRON MICROSCOPY (3 Å)