8dfa

type I-C Cascade bound to ssDNA target

spinqualitylabelsall models 8dfa, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8dfa is a 13 chain structure with sequence from Desulfovibrio vulgaris and Desulfovibrio vulgaris str. Hildenborough. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.8Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed 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. Structural snapshots of R-loop formation by a type I-C CRISPR Cascade.,O'Brien RE, Bravo JPK, Ramos D, Hibshman GN, Wright JT, Taylor DW Mol Cell. 2023 Mar 2;83(5):746-758.e5. doi: 10.1016/j.molcel.2023.01.024. Epub , 2023 Feb 16. PMID:36805026 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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