7SVW

Strand-transfer complex of TnsB from ShCAST


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Resolution: 3.69 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Mechanistic details of CRISPR-associated transposon recruitment and integration revealed by cryo-EM.

Park, J.U.Tsai, A.W.Chen, T.H.Peters, J.E.Kellogg, E.H.

(2022) Proc Natl Acad Sci U S A 119: e2202590119-e2202590119

  • DOI: 10.1073/pnas.2202590119
  • Primary Citation of Related Structures:  
    7SVV, 7SVW

  • PubMed Abstract: 
  • CRISPR-associated transposons (CASTs) are Tn7-like elements that are capable of RNA-guided DNA integration. Although structural data are known for nearly all core transposition components, the transposase component, TnsB, remains uncharacterized. Using cryo-electron microscopy (cryo-EM) structure determination, we reveal the conformation of TnsB during transposon integration for the type V-K CAST system from Scytonema hofmanni (ShCAST) ...

    CRISPR-associated transposons (CASTs) are Tn7-like elements that are capable of RNA-guided DNA integration. Although structural data are known for nearly all core transposition components, the transposase component, TnsB, remains uncharacterized. Using cryo-electron microscopy (cryo-EM) structure determination, we reveal the conformation of TnsB during transposon integration for the type V-K CAST system from Scytonema hofmanni (ShCAST). Our structure of TnsB is a tetramer, revealing strong mechanistic relationships with the overall architecture of RNaseH transposases/integrases in general, and in particular the MuA transposase from bacteriophage Mu. However, key structural differences in the C-terminal domains indicate that TnsB's tetrameric architecture is stabilized by a different set of protein-protein interactions compared with MuA. We describe the base-specific interactions along the TnsB binding site, which explain how different CAST elements can function on cognate mobile elements independent of one another. We observe that melting of the 5' nontransferred strand of the transposon end is a structural feature stabilized by TnsB and furthermore is crucial for donor-DNA integration. Although not observed in the TnsB strand-transfer complex, the C-terminal end of TnsB serves a crucial role in transposase recruitment to the target site. The C-terminal end of TnsB adopts a short, structured 15-residue "hook" that decorates TnsC filaments. Unlike full-length TnsB, C-terminal fragments do not appear to stimulate filament disassembly using two different assays, suggesting that additional interactions between TnsB and TnsC are required for redistributing TnsC to appropriate targets. The structural information presented here will help guide future work in modifying these important systems as programmable gene integration tools.


    Organizational Affiliation

    Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853.



Macromolecules

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Entity ID: 4
MoleculeChainsSequence LengthOrganismDetailsImage
TnsBG [auth A],
H [auth B],
I [auth C],
J [auth D]
584[Scytonema hofmanni] UTEX 2349Mutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Protein Feature View
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  • Reference Sequence
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Entity ID: 1
MoleculeChainsLengthOrganismImage
STC_LE_ForA [auth 1],
D [auth 4]
70synthetic construct
Protein Feature View
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsLengthOrganismImage
STC_LE_Rev1B [auth 2],
E [auth 5]
45synthetic construct
Protein Feature View
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  • Reference Sequence

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Entity ID: 3
MoleculeChainsLengthOrganismImage
STC_LE_Rev2C [auth 3],
F [auth 6]
20synthetic construct
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MG (Subject of Investigation/LOI)
Query on MG

Download Ideal Coordinates CCD File 
K [auth B],
L [auth D]
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Resolution: 3.69 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesR00-GM124463

Revision History  (Full details and data files)

  • Version 1.0: 2022-08-10
    Type: Initial release
  • Version 1.1: 2022-08-17
    Changes: Database references