SCCmec type IV Cch - active helicase

Experimental Data Snapshot

  • Resolution: 2.90 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.224 

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This is version 1.4 of the entry. See complete history


Staphylococcal SCCmec elements encode an active MCM-like helicase and thus may be replicative.

Mir-Sanchis, I.Roman, C.A.Misiura, A.Pigli, Y.Z.Boyle-Vavra, S.Rice, P.A.

(2016) Nat Struct Mol Biol 23: 891-898

  • DOI: https://doi.org/10.1038/nsmb.3286
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Methicillin-resistant Staphylococcus aureus (MRSA) is a public-health threat worldwide. Although the mobile genomic island responsible for this phenotype, staphylococcal cassette chromosome (SCC), has been thought to be nonreplicative, we predicted DNA-replication-related functions for some of the conserved proteins encoded by SCC. We show that one of these, Cch, is homologous to the self-loading initiator helicases of an unrelated family of genomic islands, that it is an active 3'-to-5' helicase and that the adjacent ORF encodes a single-stranded DNA-binding protein. Our 2.9-Å crystal structure of intact Cch shows that it forms a hexameric ring. Cch, like the archaeal and eukaryotic MCM-family replicative helicases, belongs to the pre-sensor II insert clade of AAA+ ATPases. Additionally, we found that SCC elements are part of a broader family of mobile elements, all of which encode a replication initiator upstream of their recombinases. Replication after excision would enhance the efficiency of horizontal gene transfer.

  • Organizational Affiliation

    Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Active helicase
A, B
603Staphylococcus aureusMutation(s): 0 
Gene Names: ERS195391_02151R114_17R92_17
Find proteins for Q0WXP6 (Staphylococcus aureus)
Explore Q0WXP6 
Go to UniProtKB:  Q0WXP6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ0WXP6
Sequence Annotations
  • Reference Sequence
Small Molecules
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on MSE
A, B
Experimental Data & Validation

Experimental Data

Unit Cell:
Length ( Å )Angle ( ˚ )
a = 110.14α = 90
b = 110.14β = 90
c = 302.755γ = 120
Software Package:
Software NamePurpose
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
HKL-2000data reduction

Structure Validation

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Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)United States1R21AI117593-01

Revision History  (Full details and data files)

  • Version 1.0: 2016-08-24
    Type: Initial release
  • Version 1.1: 2016-09-14
    Changes: Database references
  • Version 1.2: 2016-10-19
    Changes: Database references
  • Version 1.3: 2017-09-13
    Changes: Author supporting evidence, Derived calculations
  • Version 1.4: 2019-12-11
    Changes: Author supporting evidence