8DFA
type I-C Cascade bound to ssDNA target
Summary for 8DFA
| Entry DOI | 10.2210/pdb8dfa/pdb |
| EMDB information | 27403 |
| Descriptor | pre-crRNA processing endonuclease, CRISPR-associated protein, TM1801 family, CRISPR-associated protein, CT1133 family, ... (6 entities in total) |
| Functional Keywords | crispr, type i-c, cascade, ssdna target, dna binding protein, dna binding protein-dna-rna complex, dna binding protein/dna/rna |
| Biological source | Desulfovibrio vulgaris str. Hildenborough More |
| Total number of polymer chains | 13 |
| Total formula weight | 368984.84 |
| Authors | O'Brien, R.E.,Bravo, J.P.K.,Ramos, D.,Hibshman, G.N.,Wright, J.T.,Taylor, D.W. (deposition date: 2022-06-21, release date: 2023-02-22, Last modification date: 2025-05-28) |
| Primary citation | O'Brien, R.E.,Bravo, J.P.K.,Ramos, D.,Hibshman, G.N.,Wright, J.T.,Taylor, D.W. Structural snapshots of R-loop formation by a type I-C CRISPR Cascade. Mol.Cell, 83:746-, 2023 Cited by PubMed Abstract: Type I CRISPR-Cas systems employ multi-subunit Cascade effector complexes to target foreign nucleic acids for destruction. Here, we present structures of D. vulgaris type I-C Cascade at various stages of double-stranded (ds)DNA target capture, revealing mechanisms that underpin PAM recognition and Cascade allosteric activation. We uncover an interesting mechanism of non-target strand (NTS) DNA stabilization via stacking interactions with the "belly" subunits, securing the NTS in place. This "molecular seatbelt" mechanism facilitates efficient R-loop formation and prevents dsDNA reannealing. Additionally, we provide structural insights into how two anti-CRISPR (Acr) proteins utilize distinct strategies to achieve a shared mechanism of type I-C Cascade inhibition by blocking PAM scanning. These observations form a structural basis for directional R-loop formation and reveal how different Acr proteins have converged upon common molecular mechanisms to efficiently shut down CRISPR immunity. PubMed: 36805026DOI: 10.1016/j.molcel.2023.01.024 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (2.8 Å) |
Structure validation
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