9z7q
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Cryo-EM Structure of the Type III-Bv CRISPR Complex from Dissulfurispira thermophila bound to a crRNA
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Structural highlights
FunctionPublication Abstract from PubMedCas7-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. Identification and structure determination of a type III-Bv CRISPR complex that post-translationally modifies an associated toxin.,Pandey S, Burman N, Henriques WS, Wiegand T, Zahl T, Nyquist H, Spreeuw T, Buyukyoruk M, Wiedenheft B Structure. 2026 Jul 1:S0969-2126(26)00183-8. doi: 10.1016/j.str.2026.06.002. PMID:42385699[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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This page was last modified 07:18, 15 July 2026.