6J9K image
Entry Detail
PDB ID:
6J9K
Title:
Apo-AcrIIC2
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2019-01-23
Release Date:
2019-03-06
Method Details:
Experimental Method:
Resolution:
2.23 Å
R-Value Free:
0.24
R-Value Work:
0.20
R-Value Observed:
0.20
Space Group:
P 63 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:AcrIIC2
Chain IDs:A
Chain Length:125
Number of Molecules:1
Biological Source:Neisseria meningitidis
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
MSE A MET modified residue
Ligand Molecules
Primary Citation
Diverse Mechanisms of CRISPR-Cas9 Inhibition by Type IIC Anti-CRISPR Proteins.
Mol. Cell 74 296 309.e7 (2019)
PMID: 30850331 DOI: 10.1016/j.molcel.2019.01.038

Abstact

Anti-CRISPR proteins (Acrs) targeting CRISPR-Cas9 systems represent natural "off switches" for Cas9-based applications. Recently, AcrIIC1, AcrIIC2, and AcrIIC3 proteins were found to inhibit Neisseria meningitidis Cas9 (NmeCas9) activity in bacterial and human cells. Here we report biochemical and structural data that suggest molecular mechanisms of AcrIIC2- and AcrIIC3-mediated Cas9 inhibition. AcrIIC2 dimer interacts with the bridge helix of Cas9, interferes with RNA binding, and prevents DNA loading into Cas9. AcrIIC3 blocks the DNA loading step through binding to a non-conserved surface of the HNH domain of Cas9. AcrIIC3 also forms additional interactions with the REC lobe of Cas9 and induces the dimerization of the AcrIIC3-Cas9 complex. While AcrIIC2 targets Cas9 orthologs from different subtypes, albeit with different efficiency, AcrIIC3 specifically inhibits NmeCas9. Structure-guided changes in NmeCas9 orthologs convert them into anti-CRISPR-sensitive proteins. Our studies provide insights into anti-CRISPR-mediated suppression mechanisms and guidelines for designing regulatory tools in Cas9-based applications.

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Primary Citation of related structures