Escherichia coli SecA, the preprotein translocase dimeric ATPase

Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.213 

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Structure of dimeric SecA, the Escherichia coli preprotein translocase motor.

Papanikolau, Y.Papadovasilaki, M.Ravelli, R.B.McCarthy, A.A.Cusack, S.Economou, A.Petratos, K.

(2007) J Mol Biol 366: 1545-1557

  • DOI: https://doi.org/10.1016/j.jmb.2006.12.049
  • Primary Citation of Related Structures:  
    2FSF, 2FSG, 2FSH, 2FSI

  • PubMed Abstract: 

    SecA is the preprotein translocase ATPase subunit and a superfamily 2 (SF2) RNA helicase. Here we present the 2 A crystal structures of the Escherichia coli SecA homodimer in the apo form and in complex with ATP, ADP and adenosine 5'-[beta,gamma-imido]triphosphate (AMP-PNP). Each monomer contains the SF2 ATPase core (DEAD motor) built of two domains (nucleotide binding domain, NBD and intramolecular regulator of ATPase 2, IRA2), the preprotein binding domain (PBD), which is inserted in NBD and a carboxy-terminal domain (C-domain) linked to IRA2. The structures of the nucleotide complexes of SecA identify an interfacial nucleotide-binding cleft located between the two DEAD motor domains and residues critical for ATP catalysis. The dimer comprises two virtually identical protomers associating in an antiparallel fashion. Dimerization is mediated solely through extensive contacts of the DEAD motor domains leaving the C-domain facing outwards from the dimerization core. This dimerization mode explains the effect of functionally important mutations and is completely different from the dimerization models proposed for other SecA structures. The repercussion of these findings on translocase assembly and catalysis is discussed.

  • Organizational Affiliation

    Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, PO Box 1385, 71110 Heraklion, Greece.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Preprotein translocase secA subunit
A, B
853Escherichia coliMutation(s): 0 
Gene Names: secAazipeaprlD
Find proteins for P10408 (Escherichia coli (strain K12))
Explore P10408 
Go to UniProtKB:  P10408
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP10408
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.213 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 75.03α = 90
b = 90.171β = 100.48
c = 163.049γ = 90
Software Package:
Software NamePurpose
XSCALEdata scaling
PDB_EXTRACTdata extraction
XDSdata reduction
MOSFLMdata reduction
CCP4data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-01-16
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance