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Open data
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Basic information
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| Title | Cryo-EM structure of the NbaCas9-guide RNA-target DNA complex | ||||||||||||
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Keywords | RNA-guided DNA nuclease / RNA BINDING PROTEIN | ||||||||||||
| Function / homology | : Function and homology information | ||||||||||||
| Biological species | Nitrospirota bacterium (bacteria) / synthetic construct (others) | ||||||||||||
| Method | single particle reconstruction / cryo EM / Resolution: 2.85 Å | ||||||||||||
Authors | Nagahata N / Yamada S / Yamashita K / Nishimasu H | ||||||||||||
| Funding support | Japan, 3 items
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Citation | Journal: Nat Struct Mol Biol / Year: 2026Title: Structural visualization of the molecular evolution of CRISPR-Cas9. Authors: Naoto Nagahata / Kazuki Kato / Sota Yamada / Soumya Kannan / Sae Okazaki / Yukari Isayama / Masahiro Hiraizumi / Keitaro Yamashita / Eugene V Koonin / Feng Zhang / Hiroshi Nishimasu / ![]() Abstract: RNA-guided DNA nucleases Cas9 and IscB (insertion sequences Cas9-like OrfB) are components of type II CRISPR-Cas adaptive immune systems and transposon-associated OMEGA (obligate mobile element- ...RNA-guided DNA nucleases Cas9 and IscB (insertion sequences Cas9-like OrfB) are components of type II CRISPR-Cas adaptive immune systems and transposon-associated OMEGA (obligate mobile element-guided activity) systems, respectively. Sequence and structural comparisons indicate that IscB (~500 residues) evolved into Cas9 (~700-1,600 residues) through protein expansion coupled with guide RNA miniaturization. However, the specific sequence of events in this evolutionary transition remains unknown. Here, we report cryo-electron microscopy structures of four phylogenetically diverse RNA-guided nucleases-two IscBs and two Cas9s-each in complex with its cognate guide RNA and target DNA. Comparisons of these four complex structures to previously reported IscB and Cas9 structures indicate that evolution from IscB to Cas9 involved the loss of the N-terminal PLMP domain and the acquisition of the zinc-finger-containing REC3 domain, followed by bridge helix extension and REC1 domain acquisition. These structural changes led to expansion of the REC lobe, increasing the target DNA cleavage specificity. Additionally, the structural conservation of the RNA scaffolds indicates that the dual CRISPR RNA (crRNA) and trans-activating crRNA guides of CRISPR-Cas9 evolved from the single ωRNA guides of OMEGA systems. Our findings provide insights into the succession of structural changes involved in the exaptation of transposon-associated RNA-guided nucleases for the role of effector nucleases in adaptive immune systems. | ||||||||||||
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Structure visualization
| Supplemental images |
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Downloads & links
-EMDB archive
| Map data | emd_62004.map.gz | 17.9 MB | EMDB map data format | |
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| Header (meta data) | emd-62004-v30.xml emd-62004.xml | 25 KB 25 KB | Display Display | EMDB header |
| FSC (resolution estimation) | emd_62004_fsc.xml | 6.9 KB | Display | FSC data file |
| Images | emd_62004.png | 107.4 KB | ||
| Masks | emd_62004_msk_1.map | 35.3 MB | Mask map | |
| Filedesc metadata | emd-62004.cif.gz | 7.2 KB | ||
| Others | emd_62004_half_map_1.map.gz emd_62004_half_map_2.map.gz | 32.8 MB 32.8 MB | ||
| Archive directory | http://ftp.pdbj.org/pub/emdb/structures/EMD-62004 ftp://ftp.pdbj.org/pub/emdb/structures/EMD-62004 | HTTPS FTP |
-Related structure data
| Related structure data | ![]() 9k32MC ![]() 9k2zC ![]() 9k30C ![]() 9k31C M: atomic model generated by this map C: citing same article ( |
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| Similar structure data | Similarity search - Function & homology F&H Search |
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Links
| EMDB pages | EMDB (EBI/PDBe) / EMDataResource |
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Map
| File | Download / File: emd_62004.map.gz / Format: CCP4 / Size: 35.3 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES) | ||||||||||||||||||||||||||||||||||||
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| Projections & slices | Image control
Images are generated by Spider. | ||||||||||||||||||||||||||||||||||||
| Voxel size | X=Y=Z: 1.10667 Å | ||||||||||||||||||||||||||||||||||||
| Density |
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| Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||
| Details | EMDB XML:
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-Supplemental data
-Mask #1
| File | emd_62004_msk_1.map | ||||||||||||
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-Half map: #2
| File | emd_62004_half_map_1.map | ||||||||||||
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| Density Histograms |
-Half map: #1
| File | emd_62004_half_map_2.map | ||||||||||||
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| Density Histograms |
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Sample components
-Entire : Cryo-EM structure of the NbCas9-guide RNA-target DNA complex
| Entire | Name: Cryo-EM structure of the NbCas9-guide RNA-target DNA complex |
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| Components |
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-Supramolecule #1: Cryo-EM structure of the NbCas9-guide RNA-target DNA complex
| Supramolecule | Name: Cryo-EM structure of the NbCas9-guide RNA-target DNA complex type: complex / ID: 1 / Parent: 0 / Macromolecule list: #1-#4 |
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| Source (natural) | Organism: Nitrospirota bacterium (bacteria) |
-Macromolecule #1: HNH nuclease domain-containing protein
| Macromolecule | Name: HNH nuclease domain-containing protein / type: protein_or_peptide / ID: 1 / Number of copies: 1 / Enantiomer: LEVO |
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| Source (natural) | Organism: Nitrospirota bacterium (bacteria) |
| Molecular weight | Theoretical: 84.610656 KDa |
| Recombinant expression | Organism: ![]() |
| Sequence | String: GSEKELVLGI AYGGKYTGLG VVDRRNNQVL YARTIKMRDD VADILKGRRE QRGIRRTQQT RKKRLRELKK YLNSIGYDNS TELFKSIYS LAHKRGYDYA DMPTPEEIEE MDEKEKKEWK DTQRNSRYRK EVLADVRKVM SNGGASDEQI KRVESIFNKQ Y RPKRFNNR ...String: GSEKELVLGI AYGGKYTGLG VVDRRNNQVL YARTIKMRDD VADILKGRRE QRGIRRTQQT RKKRLRELKK YLNSIGYDNS TELFKSIYS LAHKRGYDYA DMPTPEEIEE MDEKEKKEWK DTQRNSRYRK EVLADVRKVM SNGGASDEQI KRVESIFNKQ Y RPKRFNNR ILTKCKVCGK NTPLRRNVRE LLLENIVRFL PLESELKETL KRTILEGQQG NINKLFRKLK FNQKDWPGKN LT DIAKNKL PGRLPFCKEH FAENEKFTTI EKSTFRLAPS LKTKIENVLT VIKDEVMPNF ALDRVVMESN NFDIAAKTKG KKR LAKEEY SKGHKENRET LMESLLRETD GRCVYCGKTI TLADANKDAI YPKKAGGSNI FANLVACCRS CNENKGGRTP SESG IMPNP EVVATIKNDL KKKILDDARS IKQLDFNKYM SHASIGWRHM RDRLKELTGN DKLPVERLSG IVTAYFRRWW GFKKE RAND KHHALDAVIL ASRKDYTDEG LVAMTLKPAN SDGREFDPEK HIKESEEFKR NKGSRGSALY DKNPLSIKNG KIARRY MVT EIERGKEDAV ISEEWREKLK EAFDRFGVSN GKCLTDLQTK EVGLYGQKNP MSLKCAVRGA GKGQIVLIGN NAFKTNV HN VGVAVYLDEK GKKRACELKN QRLAKHFVEP QDEIKGKILF TLRKGDTVKA EDGNIYRILE LGERPVVDIK WVPTSDGK K KRVKTAIHAT KLTKL UniProtKB: UNIPROTKB: A0A3C0V2Q6 |
-Macromolecule #2: Guide RNA
| Macromolecule | Name: Guide RNA / type: rna / ID: 2 / Number of copies: 1 |
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| Source (natural) | Organism: Nitrospirota bacterium (bacteria) |
| Molecular weight | Theoretical: 62.928344 KDa |
| Sequence | String: GGGGAAAUUA GGUGCGCUUG GCGUUACAGU UAAGGCUCUU UGAAAAUGAU GAUUGAAACG AAAAAAGAGC CUUAAUUGUA AAACGCCUA UAUGAUGAAG GAAUGUACGC UUGGGUUUGU CCAGCCUAAG CCAAACUAAA ACUACAGUCG AUAAUGACAC C UUCAUUGU ...String: GGGGAAAUUA GGUGCGCUUG GCGUUACAGU UAAGGCUCUU UGAAAAUGAU GAUUGAAACG AAAAAAGAGC CUUAAUUGUA AAACGCCUA UAUGAUGAAG GAAUGUACGC UUGGGUUUGU CCAGCCUAAG CCAAACUAAA ACUACAGUCG AUAAUGACAC C UUCAUUGU GGGUUAGGAC AUUAAAAAAA UUUUCAG |
-Macromolecule #3: Target DNA strand
| Macromolecule | Name: Target DNA strand / type: dna / ID: 3 / Number of copies: 1 / Classification: DNA |
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| Source (natural) | Organism: synthetic construct (others) |
| Molecular weight | Theoretical: 12.973302 KDa |
| Sequence | String: (DA)(DC)(DC)(DC)(DG)(DT)(DT)(DC)(DC)(DC) (DC)(DG)(DC)(DC)(DA)(DA)(DG)(DC)(DG)(DC) (DA)(DC)(DC)(DT)(DA)(DA)(DT)(DT)(DT) (DC)(DC)(DC)(DC)(DG)(DG)(DG)(DA)(DT)(DC) (DC) (DT)(DC)(DT) |
-Macromolecule #4: Non-target DNA strand
| Macromolecule | Name: Non-target DNA strand / type: dna / ID: 4 / Number of copies: 1 / Classification: DNA |
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| Source (natural) | Organism: synthetic construct (others) |
| Molecular weight | Theoretical: 13.498658 KDa |
| Sequence | String: (DA)(DG)(DA)(DG)(DG)(DA)(DT)(DC)(DC)(DC) (DG)(DG)(DG)(DG)(DA)(DA)(DA)(DT)(DT)(DA) (DG)(DG)(DA)(DC)(DG)(DC)(DG)(DA)(DA) (DC)(DC)(DG)(DG)(DG)(DG)(DG)(DA)(DA)(DC) (DG) (DG)(DG)(DT) |
-Macromolecule #5: MAGNESIUM ION
| Macromolecule | Name: MAGNESIUM ION / type: ligand / ID: 5 / Number of copies: 3 / Formula: MG |
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| Molecular weight | Theoretical: 24.305 Da |
-Macromolecule #6: ZINC ION
| Macromolecule | Name: ZINC ION / type: ligand / ID: 6 / Number of copies: 2 / Formula: ZN |
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| Molecular weight | Theoretical: 65.409 Da |
-Macromolecule #7: water
| Macromolecule | Name: water / type: ligand / ID: 7 / Number of copies: 9 / Formula: HOH |
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| Molecular weight | Theoretical: 18.015 Da |
| Chemical component information | ![]() ChemComp-HOH: |
-Experimental details
-Structure determination
| Method | cryo EM |
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Processing | single particle reconstruction |
| Aggregation state | particle |
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Sample preparation
| Buffer | pH: 6 |
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| Vitrification | Cryogen name: ETHANE |
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Electron microscopy
| Microscope | TFS KRIOS |
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| Image recording | Film or detector model: GATAN K3 BIOQUANTUM (6k x 4k) / Average electron dose: 50.0 e/Å2 |
| Electron beam | Acceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN |
| Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Nominal defocus max: 2.0 µm / Nominal defocus min: 0.8 µm |
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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About Yorodumi




Keywords
Nitrospirota bacterium (bacteria)
Authors
Japan, 3 items
Citation







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Processing
FIELD EMISSION GUN

