8YB6

Type I-EHNH Cascade complex

Summary for 8YB6

• Entry DOI: 10.2210/pdb8yb6/pdb
• EMDB information: 39110
• Descriptor: CRISPR system Cascade subunit CasD, CRISPR-associated endoribonuclease Cse3, 61-nt crRNA, ... (7 entities in total)
• Functional Keywords: rna pro, rna binding protein/rna, rna binding protein-rna complex
• Biological source: Candidatus Cloacimonetes bacterium ADurb.Bin088; More
• Total number of polymer chains: 11
• Total formula weight: 426384.91

Authors

Li, Z. (deposition date: 2024-02-11, release date: 2024-07-31, Last modification date: 2024-09-11)

Primary citation

Zhang, C.,Chen, F.,Wang, F.,Xu, H.,Xue, J.,Li, Z.
Mechanisms for HNH-mediated target DNA cleavage in type I CRISPR-Cas systems.
Mol.Cell, 84:3141-, 2024

PubMed Abstract: The metagenome-derived type I-E and type I-F variant CRISPR-associated complex for antiviral defense (Cascade) complexes, fused with HNH domains, precisely cleave target DNA, representing recently identified genome editing tools. However, the underlying working mechanisms remain unknown. Here, structures of type I-F and I-E Cascade complexes at different states are reported. In type I-F Cascade, Cas8f loosely attaches to Cascade head and is adjacent to the 5' end of the target single-stranded DNA (ssDNA). Formation of the full R-loop drives the Cascade head to move outward, allowing Cas8f to detach and rotate ∼150° to accommodate target ssDNA for cleavage. In type I-E Cascade, Cas5e domain is adjacent to the 5' end of the target ssDNA. Full crRNA-target pairing drives the lift of the Cascade head, widening the substrate channel for target ssDNA entrance. Altogether, these analyses into both complexes revealed that crRNA-guided positioning of target DNA and target DNA-induced HNH unlocking are two key factors for their site-specific cleavage of target DNA.

PubMed: 39047725
DOI: 10.1016/j.molcel.2024.06.033

Experimental method

ELECTRON MICROSCOPY (3.06 Å)