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- PDB-8hnv: CryoEM structure of HpaCas9-sgRNA-dsDNA in the presence of AcrIIC4 -
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Open data
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Basic information
Entry | Database: PDB / ID: 8hnv | ||||||
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Title | CryoEM structure of HpaCas9-sgRNA-dsDNA in the presence of AcrIIC4 | ||||||
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![]() | ANTIMICROBIAL PROTEIN / Cas9 / cleavage inhibition / HYDROLASE-RNA-ANTIMICROBIAL PROTEIN complex | ||||||
Function / homology | ![]() maintenance of CRISPR repeat elements / endonuclease activity / defense response to virus / Hydrolases; Acting on ester bonds / DNA binding / RNA binding / metal ion binding Similarity search - Function | ||||||
Biological species | ![]() synthetic construct (others) | ||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.1 Å | ||||||
![]() | Sun, W. / Cheng, Z. / Wang, J. / Yang, X. / Wang, Y. | ||||||
Funding support | ![]()
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![]() | ![]() Title: AcrIIC4 inhibits type II-C Cas9 by preventing R-loop formation. Authors: Wei Sun / Zhi Cheng / Jiuyu Wang / Jing Yang / Xueyan Li / Jinlong Wang / Minxuan Chen / Xiaoqi Yang / Gang Sheng / Jizhong Lou / Yanli Wang / ![]() Abstract: Anti-CRISPR (Acr) proteins are encoded by phages and other mobile genetic elements and inhibit host CRISPR-Cas immunity using versatile strategies. AcrIIC4 is a broad-spectrum Acr that inhibits the ...Anti-CRISPR (Acr) proteins are encoded by phages and other mobile genetic elements and inhibit host CRISPR-Cas immunity using versatile strategies. AcrIIC4 is a broad-spectrum Acr that inhibits the type II-C CRISPR-Cas9 system in several species by an unknown mechanism. Here, we determined a series of structures of Cas9 (HpaCas9)-sgRNA in complex with AcrIIC4 and/or target DNA, as well as the crystal structure of AcrIIC4 alone. We found that AcrIIC4 resides in the crevice between the REC1 and REC2 domains of HpaCas9, where its extensive interactions restrict the mobility of the REC2 domain and prevent the unwinding of target double-stranded (ds) DNA at the PAM-distal end. Therefore, the full-length guide RNA:target DNA heteroduplex fails to form in the presence of AcrIIC4, preventing Cas9 nuclease activation. Altogether, our structural and biochemical studies illuminate a unique Acr mechanism that allows DNA binding to the Cas9 effector complex but blocks its cleavage by preventing R-loop formation, a key step supporting DNA cleavage by Cas9. #1: Journal: mBio / Year: 2018 Title: Potent Cas9 Inhibition in Bacterial and Human Cells by AcrIIC4 and AcrIIC5 Anti-CRISPR Proteins. Authors: Jooyoung Lee / Aamir Mir / Alireza Edraki / Bianca Garcia / Nadia Amrani / Hannah E Lou / Ildar Gainetdinov / April Pawluk / Raed Ibraheim / Xin D Gao / Pengpeng Liu / Alan R Davidson / ...Authors: Jooyoung Lee / Aamir Mir / Alireza Edraki / Bianca Garcia / Nadia Amrani / Hannah E Lou / Ildar Gainetdinov / April Pawluk / Raed Ibraheim / Xin D Gao / Pengpeng Liu / Alan R Davidson / Karen L Maxwell / Erik J Sontheimer / ![]() ![]() Abstract: In their natural settings, CRISPR-Cas systems play crucial roles in bacterial and archaeal adaptive immunity to protect against phages and other mobile genetic elements, and they are also widely used ...In their natural settings, CRISPR-Cas systems play crucial roles in bacterial and archaeal adaptive immunity to protect against phages and other mobile genetic elements, and they are also widely used as genome engineering technologies. Previously we discovered bacteriophage-encoded Cas9-specific anti-CRISPR (Acr) proteins that serve as countermeasures against host bacterial immunity by inactivating their CRISPR-Cas systems (A. Pawluk, N. Amrani, Y. Zhang, B. Garcia, et al., Cell 167:1829-1838.e9, 2016, https://doi.org/10.1016/j.cell.2016.11.017). We hypothesized that the evolutionary advantages conferred by anti-CRISPRs would drive the widespread occurrence of these proteins in nature (K. L. Maxwell, Mol Cell 68:8-14, 2017, https://doi.org/10.1016/j.molcel.2017.09.002; A. Pawluk, A. R. Davidson, and K. L. Maxwell, Nat Rev Microbiol 16:12-17, 2018, https://doi.org/10.1038/nrmicro.2017.120; E. J. Sontheimer and A. R. Davidson, Curr Opin Microbiol 37:120-127, 2017, https://doi.org/10.1016/j.mib.2017.06.003). We have identified new anti-CRISPRs using the same bioinformatic approach that successfully identified previous Acr proteins (A. Pawluk, N. Amrani, Y. Zhang, B. Garcia, et al., Cell 167:1829-1838.e9, 2016, https://doi.org/10.1016/j.cell.2016.11.017) against Cas9 (NmeCas9). In this work, we report two novel anti-CRISPR families in strains of and , both of which harbor type II-C CRISPR-Cas systems (A. Mir, A. Edraki, J. Lee, and E. J. Sontheimer, ACS Chem Biol 13:357-365, 2018, https://doi.org/10.1021/acschembio.7b00855). We characterize the type II-C Cas9 orthologs from and , show that the newly identified Acrs are able to inhibit these systems, and define important features of their inhibitory mechanisms. The Acr is the most potent NmeCas9 inhibitor identified to date. Although inhibition of NmeCas9 by anti-CRISPRs from and reveals cross-species inhibitory activity, more distantly related type II-C Cas9s are not inhibited by these proteins. The specificities of anti-CRISPRs and divergent Cas9s appear to reflect coevolution of their strategies to combat or evade each other. Finally, we validate these new anti-CRISPR proteins as potent off-switches for Cas9 genome engineering applications. As one of their countermeasures against CRISPR-Cas immunity, bacteriophages have evolved natural inhibitors known as anti-CRISPR (Acr) proteins. Despite the existence of such examples for type II CRISPR-Cas systems, we currently know relatively little about the breadth of Cas9 inhibitors, and most of their direct Cas9 targets are uncharacterized. In this work we identify two new type II-C anti-CRISPRs and their cognate Cas9 orthologs, validate their functionality and in bacteria, define their inhibitory spectrum against a panel of Cas9 orthologs, demonstrate that they act before Cas9 DNA binding, and document their utility as off-switches for Cas9-based tools in mammalian applications. The discovery of diverse anti-CRISPRs, the mechanistic analysis of their cognate Cas9s, and the definition of Acr inhibitory mechanisms afford deeper insight into the interplay between Cas9 orthologs and their inhibitors and provide greater scope for exploiting Acrs for CRISPR-based genome engineering. | ||||||
History |
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Structure visualization
Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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PDBx/mmCIF format | ![]() | 235.8 KB | Display | ![]() |
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PDB format | ![]() | 167.5 KB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
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-Validation report
Arichive directory | ![]() ![]() | HTTPS FTP |
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-Related structure data
Related structure data | ![]() 34919MC ![]() 8hnsC ![]() 8hntC ![]() 8hnwC M: map data used to model this data C: citing same article ( |
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Similar structure data | Similarity search - Function & homology ![]() |
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Links
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Assembly
Deposited unit | ![]()
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Components
#1: Protein | Mass: 121605.695 Da / Num. of mol.: 1 / Mutation: D13A,H581A Source method: isolated from a genetically manipulated source Details: Two mutations D13A and H581A were introduced to inactivate the catalytic sites of HpaCas9. The first residue 'Ser' of the sample sequence is the one expressed from the vector left after tag cleavage. Source: (gene. exp.) ![]() ![]() ![]() |
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#2: RNA chain | Mass: 40860.125 Da / Num. of mol.: 1 / Source method: obtained synthetically Details: RNA is originally derived from Haemophilus parainfluenzae and modified by author. Source: (synth.) synthetic construct (others) |
#3: DNA chain | Mass: 10865.029 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) ![]() |
#4: DNA chain | Mass: 10766.954 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) ![]() |
#5: Protein | Mass: 10072.395 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Details: WP_049372635.1;The first residue 'Ser' of the sample sequence is the one expressed from the vector left after tag cleavage. Source: (gene. exp.) ![]() ![]() ![]() |
-Experimental details
-Experiment
Experiment | Method: ELECTRON MICROSCOPY |
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EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
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Sample preparation
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Molecular weight | Value: 0.194 MDa / Experimental value: YES | ||||||||||||||||||||||||
Source (natural) | Organism: ![]() | ||||||||||||||||||||||||
Source (recombinant) | Organism: ![]() ![]() | ||||||||||||||||||||||||
Buffer solution | pH: 7.5 | ||||||||||||||||||||||||
Buffer component |
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Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES | ||||||||||||||||||||||||
Vitrification | Cryogen name: ETHANE / Humidity: 100 % / Chamber temperature: 277 K |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: FEI TITAN KRIOS |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal defocus max: 1600 nm / Nominal defocus min: 1000 nm |
Image recording | Electron dose: 60 e/Å2 / Film or detector model: GATAN K2 QUANTUM (4k x 4k) |
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Processing
CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||
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3D reconstruction | Resolution: 3.1 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 212049 / Symmetry type: POINT | ||||||||||||||||||||||||
Atomic model building | Protocol: RIGID BODY FIT | ||||||||||||||||||||||||
Refinement | Cross valid method: NONE Stereochemistry target values: GeoStd + Monomer Library + CDL v1.2 | ||||||||||||||||||||||||
Displacement parameters | Biso mean: 17.66 Å2 | ||||||||||||||||||||||||
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