Co-crystal structure of SV40 large T antigen helicase domain and ADP

Experimental Data Snapshot

  • Resolution: 1.95 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.236 

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Mechanisms of conformational change for a replicative hexameric helicase of SV40 large tumor antigen.

Gai, D.Zhao, R.Li, D.Finkielstein, C.V.Chen, X.S.

(2004) Cell 119: 47-60

  • DOI: https://doi.org/10.1016/j.cell.2004.09.017
  • Primary Citation of Related Structures:  
    1SVL, 1SVM, 1SVO

  • PubMed Abstract: 

    The large tumor antigen (LTag) of simian virus 40, an AAA(+) protein, is a hexameric helicase essential for viral DNA replication in eukaryotic cells. LTag functions as an efficient molecular machine powered by ATP binding and hydrolysis for origin DNA melting and replication fork unwinding. To understand how ATP binding and hydrolysis are coupled to conformational changes, we have determined high-resolution structures ( approximately 1.9 A) of LTag hexamers in distinct nucleotide binding states. The structural differences of LTag in various nucleotide states detail the molecular mechanisms of conformational changes triggered by ATP binding/hydrolysis and reveal a potential mechanism of concerted nucleotide binding and hydrolysis. During these conformational changes, the angles and orientations between domains of a monomer alter, creating an "iris"-like motion in the hexamer. Additionally, six unique beta hairpins on the channel surface move longitudinally along the central channel, possibly serving as a motor for pulling DNA into the LTag double hexamer for unwinding.

  • Organizational Affiliation

    Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, Denver, CO 80262, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
large T antigen
A, B, C
377Betapolyomavirus macacaeMutation(s): 0 
Find proteins for P03070 (Simian virus 40)
Explore P03070 
Go to UniProtKB:  P03070
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP03070
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.95 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.236 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 195.812α = 90
b = 86.442β = 129
c = 128.601γ = 90
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: 2004-10-19
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-14
    Changes: Data collection, Database references, Derived calculations