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-Structure paper
Title | Mechanisms for HNH-mediated target DNA cleavage in type I CRISPR-Cas systems. |
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Journal, issue, pages | Mol Cell, Vol. 84, Issue 16, Page 3141-33153.e5, Year 2024 |
Publish date | Jul 12, 2024 |
![]() | Chendi Zhang / Fugen Chen / Feng Wang / Haijiang Xu / Jialin Xue / Zhuang Li / ![]() |
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 ...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. |
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Methods | EM (single particle) |
Resolution | 3.06 - 3.44 Å |
Structure data | EMDB-39110, PDB-8yb6: EMDB-39167, PDB-8ydb: EMDB-39200, PDB-8yeo: EMDB-39285, PDB-8yh9: EMDB-39286, PDB-8yha: |
Chemicals | ![]() ChemComp-ZN: |
Source |
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![]() | RNA BINDING PROTEIN/RNA / RNA pro / RNA BINDING PROTEIN-RNA complex / RNA BINDING PROTEIN/DNA/RNA / protein / RNA / RNA BINDING PROTEIN-DNA-RNA complex |