Crystal structure of the homing endonuclease I-MsoI bound to its DNA substrate

Experimental Data Snapshot

  • Resolution: 2.25 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.219 

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Flexible DNA Target Site Recognition by Divergent Homing Endonuclease Isoschizomers I-CreI and I-MsoI

Chevalier, B.Turmel, M.Lemieux, C.Monnat, R.J.Stoddard, B.L.

(2003) J Mol Biol 329: 253-269

  • DOI: https://doi.org/10.1016/s0022-2836(03)00447-9
  • Primary Citation of Related Structures:  
    1M5X, 1N3E, 1N3F

  • PubMed Abstract: 

    Homing endonucleases are highly specific catalysts of DNA strand breaks that induce the transposition of mobile intervening sequences containing the endonuclease open reading frame. These enzymes recognize long DNA targets while tolerating individual sequence polymorphisms within those sites. Sequences of the homing endonucleases themselves diversify to a great extent after founding intron invasion events, generating highly divergent enzymes that recognize similar target sequences. Here, we visualize the mechanism of flexible DNA recognition and the pattern of structural divergence displayed by two homing endonuclease isoschizomers. We determined structures of I-CreI bound to two DNA target sites that differ at eight of 22 base-pairs, and the structure of an isoschizomer, I-MsoI, bound to a nearly identical DNA target site. This study illustrates several principles governing promiscuous base-pair recognition by DNA-binding proteins, and demonstrates that the isoschizomers display strikingly different protein/DNA contacts. The structures allow us to determine the information content at individual positions in the binding site as a function of the distribution of direct and water-mediated contacts to nucleotide bases, and provide an evolutionary snapshot of endonucleases at an early stage of divergence in their target specificity.

  • Organizational Affiliation

    Division of Basic Sciences, Graduate Program in Molecular and Cellular Biology, University of Washington and the Fred Hutchinson Cancer Research Center, Seattle 98109, USA.


Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
DNA endonuclease I-MsoIC [auth A],
D [auth B]
170Monomastix sp. OKE-1Mutation(s): 0 
Find proteins for C0JWR6 (Monomastix sp. (strain OKE-1))
Explore C0JWR6 
Go to UniProtKB:  C0JWR6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupC0JWR6
Sequence Annotations
  • Reference Sequence

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Entity ID: 1
MoleculeChains LengthOrganismImage
Sequence Annotations
  • Reference Sequence

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Entity ID: 2
MoleculeChains LengthOrganismImage
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.25 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.219 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 41.51α = 73.34
b = 42.21β = 73.17
c = 71.32γ = 71.09
Software Package:
Software NamePurpose
HKL-2000data collection
SCALEPACKdata scaling
HKL-2000data reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-06-03
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.3: 2018-03-07
    Changes: Experimental preparation
  • Version 1.4: 2024-02-14
    Changes: Data collection, Database references, Derived calculations
  • Version 1.5: 2024-04-03
    Changes: Refinement description