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Open data
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Basic information
Entry | Database: PDB / ID: 8ewg | ||||||
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Title | Cryo-EM structure of a riboendonclease | ||||||
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![]() | Hydrolase/RNA / riboendonuclease / RNA / Hydrolase-RNA complex | ||||||
Function / homology | RNA / RNA (> 10) / Uncharacterized protein![]() | ||||||
Biological species | ![]() | ||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 2.9 Å | ||||||
![]() | Li, Z. / Wang, F. | ||||||
Funding support | 1items
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![]() | ![]() Title: Structural Basis for the Ribonuclease Activity of a Thermostable CRISPR-Cas13a from Thermoclostridium caenicola. Authors: Feng Wang / Chendi Zhang / Haijiang Xu / Wanting Zeng / Lixin Ma / Zhuang Li / ![]() Abstract: The RNA-targeting type VI CRISPR-Cas effector complexes are widely used in biotechnology applications such as gene knockdown, RNA editing, and molecular diagnostics. Compared with Cas13a from ...The RNA-targeting type VI CRISPR-Cas effector complexes are widely used in biotechnology applications such as gene knockdown, RNA editing, and molecular diagnostics. Compared with Cas13a from mesophilic organisms, a newly discovered Cas13a from thermophilic bacteria Thermoclostridium caenicola (TccCas13a) shows low sequence similarity, high thermostability, and lacks pre-crRNA processing activity. The thermostability of TccCas13a has been harnessed to make a sensitive and robust tool for nucleic acid detection. Here we present the structures of TccCas13a-crRNA binary complex at 2.8 Å, and TccCas13a at 3.5 Å. Although TccCas13a shares a similarly bilobed architecture with other mesophilic organism-derived Cas13a proteins, TccCas13a displayed distinct structure features. Specifically, it holds a long crRNA 5'-flank, forming extensive polar contacts with Helical-1 and HEPN2 domains. The detailed analysis of the interaction between crRNA 5'-flank and TccCas13a suggested lack of suitable nucleophile to attack the 2'-OH of crRNA 5'-flank may explain why TccCas13a fails to cleave pre-crRNA. The stem-loop segment of crRNA spacer toggles between double-stranded and single-stranded conformational states, suggesting a potential safeguard mechanism for target recognition. Superimposition of the structures of TccCas13a and TccCas13a-crRNA revealed several conformational changes required for crRNA loading, including dramatic movement of Helical-2 domain. Collectively, these structural insights expand our understanding into type VI CRISPR-Cas effectors, and would facilitate the development of TccCas13a-based applications. | ||||||
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Structure visualization
Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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Download
PDBx/mmCIF format | ![]() | 254.2 KB | Display | ![]() |
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PDB format | ![]() | 196 KB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
Others | ![]() |
-Validation report
Summary document | ![]() | 1 MB | Display | ![]() |
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Full document | ![]() | 1 MB | Display | |
Data in XML | ![]() | 39.5 KB | Display | |
Data in CIF | ![]() | 61.8 KB | Display | |
Arichive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 28645MC ![]() 8h4uC 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: 143582.641 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() ![]() |
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#2: RNA chain | Mass: 19301.541 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) ![]() |
-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
Component | Name: Binary complex of a riboendonuclease with its cognate RNA Type: COMPLEX / Entity ID: all / Source: RECOMBINANT |
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Source (natural) | Organism: ![]() |
Source (recombinant) | Organism: ![]() ![]() |
Buffer solution | pH: 7.5 |
Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
Vitrification | Cryogen name: ETHANE |
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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: 2500 nm / Nominal defocus min: 1500 nm |
Image recording | Electron dose: 54 e/Å2 / Film or detector model: GATAN K3 BIOQUANTUM (6k x 4k) |
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Processing
Software | Name: PHENIX / Version: 1.20.1_4487: / Classification: refinement | ||||||||||||||||||||||||
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CTF correction | Type: NONE | ||||||||||||||||||||||||
3D reconstruction | Resolution: 2.9 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 561050 / Symmetry type: POINT | ||||||||||||||||||||||||
Refine LS restraints |
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