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Open data
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Basic information
| Entry | Database: PDB / ID: 30gt | |||||||||||||||
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| Title | Cryo-EM structure of the PseCascade-TniQ-TnsC complex | |||||||||||||||
Components |
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Keywords | DNA BINDING PROTEIN / Transposase / DNA-binding / RNA-binding / CRISPR-Cas / CRISPR-associated transposon | |||||||||||||||
| Function / homology | Function and homology information | |||||||||||||||
| Biological species | Pseudoalteromonas sp. S983 (bacteria) | |||||||||||||||
| Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.3 Å | |||||||||||||||
Authors | Finocchio, G. / Oberli, S. / Schmitz, M. / Jinek, M. | |||||||||||||||
| Funding support | European Union, Switzerland, 2items
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Citation | Journal: bioRxiv / Year: 2026Title: Structural basis of RNA-guided DNA integration by type I CRISPR-associated transposases. Authors: Giada Finocchio / Seraina Oberli / George Lampe / Michael Schmitz / Samuel H Sternberg / Martin Jinek Abstract: CRISPR-associated transposases (CASTs) achieve site-specific DNA integration by coupling the RNA-guided targeting action of a nuclease-deficient CRISPR-Cas system with the assembly of a Tn7-like ...CRISPR-associated transposases (CASTs) achieve site-specific DNA integration by coupling the RNA-guided targeting action of a nuclease-deficient CRISPR-Cas system with the assembly of a Tn7-like transpososome complex . Understanding the detailed mechanisms of this elaborate process is paramount to engineering CAST systems into programmable genetic tools . The type I-F CAST ( CAST) displays the highest activity in mammalian cells to date and has been the subject of extensive directed evolution , but efforts to rationally engineer further improvements have been hampered by critical gaps in our understanding of transpososome assembly and activation . Here we use cryo-EM structural analysis, validated by DNA transposition assays, to visualize the CAST system in a series of functional states that define the stepwise mechanism of RNA-guided DNA integration. The structure of a target DNA-bound Cascade-TniQ-TnsC complex reveals that conformational changes induced by R-loop formation are coupled to target DNA stabilization and TnsC heptamerization, which in turn recruits the TnsAB transposase via conserved interactions with its C-terminal tail. Finally, the structure of the 1.2 MDa CAST transpososome holocomplex reveals specific TnsC-TnsB and TnsB-target DNA interactions that drive allosteric remodelling of the TnsB catalytic site to activate donor DNA integration. Together, these findings establish a unified structural and mechanistic blueprint for RNA-guided DNA integration and lay the foundation for engineering next-generation DNA insertion systems for genome editing applications. | |||||||||||||||
| History |
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Structure visualization
| Structure viewer | Molecule: Molmil Jmol/JSmol |
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Downloads & links
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Download
| PDBx/mmCIF format | 30gt.cif.gz | 1.2 MB | Display | PDBx/mmCIF format |
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| PDB format | pdb30gt.ent.gz | 1 MB | Display | PDB format |
| PDBx/mmJSON format | 30gt.json.gz | Tree view | PDBx/mmJSON format | |
| Others | Other downloads |
-Validation report
| Arichive directory | https://data.pdbj.org/pub/pdb/validation_reports/0g/30gt ftp://data.pdbj.org/pub/pdb/validation_reports/0g/30gt | HTTPS FTP |
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-Related structure data
| Related structure data | ![]() 57765MC ![]() 30gaC ![]() 30gbC C: citing same article ( M: map data used to model this data |
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| Similar structure data | Similarity search - Function & homology F&H Search |
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Links
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Assembly
| Deposited unit | ![]()
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| 1 |
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Components
-RNA chain , 1 types, 1 molecules 1
| #1: RNA chain | Mass: 30196.002 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Details: CRISPR RNA (crRNA) from the type I-F PseCAST (Tn7016) Cascade complex of Pseudoalteromonas sp. S983 Source: (gene. exp.) Pseudoalteromonas sp. S983 (bacteria) / Production host: ![]() |
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-DNA chain , 2 types, 2 molecules 23
| #2: DNA chain | Mass: 44605.438 Da / Num. of mol.: 1 / Source method: obtained synthetically Details: Target DNA strand complementary to the crRNA spacer sequence, fused to the transferred strand of the right transposon end via a palindromic target site duplication (TSD) sequence. TSD and ...Details: Target DNA strand complementary to the crRNA spacer sequence, fused to the transferred strand of the right transposon end via a palindromic target site duplication (TSD) sequence. TSD and right transposon end are unstructured. Source: (synth.) Pseudoalteromonas sp. S983 (bacteria) |
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| #3: DNA chain | Mass: 29085.531 Da / Num. of mol.: 1 / Source method: obtained synthetically Details: Non-target DNA strand containing a +1 to +18 region identical to the target DNA strand, rather than complementary, to facilitate crRNA annealing to the protospacer. Source: (synth.) Pseudoalteromonas sp. S983 (bacteria) |
-Protein , 5 types, 17 molecules ABCDEFGHIJKLMNOPQ
| #4: Protein | Mass: 39845.145 Da / Num. of mol.: 6 Source method: isolated from a genetically manipulated source Details: CRISPR-associated protein Cas7 from the type I-F PseCAST (Tn7016) Cascade complex of Pseudoalteromonas sp. S983. Source: (gene. exp.) Pseudoalteromonas sp. S983 (bacteria) / Production host: ![]() #5: Protein | | Mass: 79290.211 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Details: CRISPR-associated protein Cas8 from the type I-F PseCAST (Tn7016) Cascade complex of Pseudoalteromonas sp. S983. Source: (gene. exp.) Pseudoalteromonas sp. S983 (bacteria) / Production host: ![]() #6: Protein | | Mass: 26631.074 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Details: CRISPR-associated protein Cas6 from the type I-F PseCAST (Tn7016) Cascade complex of Pseudoalteromonas sp. S983, bearing a C-terminal Twin-Strep tag. Source: (gene. exp.) Pseudoalteromonas sp. S983 (bacteria) / Production host: ![]() #7: Protein | Mass: 49832.406 Da / Num. of mol.: 2 Source method: isolated from a genetically manipulated source Details: CRISPR-associated protein TniQ from the type I-F PseCAST (Tn7016) system of Pseudoalteromonas sp. S983, bearing an N-terminal His10 tag followed by a TEV protease cleavage site. Source: (gene. exp.) Pseudoalteromonas sp. S983 (bacteria) / Production host: ![]() #8: Protein | Mass: 38609.902 Da / Num. of mol.: 7 Source method: isolated from a genetically manipulated source Details: AAA+ ATPase TnsC from the type I-F PseCAST (Tn7016) system of Pseudoalteromonas sp. S983. Source: (gene. exp.) Pseudoalteromonas sp. S983 (bacteria) / Production host: ![]() |
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-Non-polymers , 2 types, 14 molecules 


| #9: Chemical | ChemComp-ATP / #10: Chemical | ChemComp-MG / |
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-Details
| Has ligand of interest | Y |
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| Has protein modification | Y |
-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: PseCascade-TniQ-TnsC complex / Type: COMPLEX Details: PseCascade-TniQ-TnsC complex. The CRISPR RNA (crRNA) is base-paired with a double-stranded DNA target. Entity ID: #1-#8 / Source: RECOMBINANT | ||||||||||||||||||||||||||||||
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| Molecular weight | Value: 0.73 MDa / Experimental value: NO | ||||||||||||||||||||||||||||||
| Source (natural) | Organism: Pseudoalteromonas sp. S983 (bacteria) | ||||||||||||||||||||||||||||||
| Source (recombinant) | Organism: ![]() | ||||||||||||||||||||||||||||||
| Buffer solution | pH: 7.5 | ||||||||||||||||||||||||||||||
| Buffer component |
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| Specimen | Conc.: 4.4 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES Details: The sample was prepared by mixing and incubating the nucleic acid substrate and the protein components. | ||||||||||||||||||||||||||||||
| Specimen support | Grid material: GOLD / Grid mesh size: 300 divisions/in. / Grid type: Quantifoil R1.2/1.3 | ||||||||||||||||||||||||||||||
| Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 100 % / Chamber temperature: 277.15 K |
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Electron microscopy imaging
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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| Microscopy | Model: TFS KRIOS |
| Electron gun | Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM |
| Electron lens | Mode: BRIGHT FIELD / Nominal magnification: 130000 X / Nominal defocus max: 2400 nm / Nominal defocus min: 1000 nm |
| Specimen holder | Cryogen: NITROGEN / Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER |
| Image recording | Average exposure time: 1.25 sec. / Electron dose: 59.672 e/Å2 / Detector mode: SUPER-RESOLUTION / Film or detector model: GATAN K3 (6k x 4k) / Num. of grids imaged: 1 / Num. of real images: 9403 |
| Image scans | Width: 5760 / Height: 4092 |
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Processing
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| CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||||||||||||||||||||||||||||
| Particle selection | Num. of particles selected: 745080 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| 3D reconstruction | Resolution: 3.3 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 76400 / Algorithm: FOURIER SPACE / Num. of class averages: 1 / Symmetry type: POINT | ||||||||||||||||||||||||||||||||||||||||||||||||||
| Atomic model building | Protocol: FLEXIBLE FIT / Space: REAL Target criteria: Real-space map-model correlation and geometry restraints | ||||||||||||||||||||||||||||||||||||||||||||||||||
| Atomic model building | Source name: AlphaFold / Type: in silico model | ||||||||||||||||||||||||||||||||||||||||||||||||||
| Refinement | Highest resolution: 3.3 Å Stereochemistry target values: REAL-SPACE (WEIGHTED MAP SUM AT ATOM CENTERS) | ||||||||||||||||||||||||||||||||||||||||||||||||||
| Refine LS restraints |
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Pseudoalteromonas sp. S983 (bacteria)
Switzerland, 2items
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FIELD EMISSION GUN