Structure of the N-terminal domain of XpsE (crystal form P43212)

Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.189 
  • R-Value Observed: 0.192 

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Structure and Function of the XpsE N-Terminal Domain, an Essential Component of the Xanthomonas campestris Type II Secretion System

Chen, Y.Shiue, S.-J.Huang, C.-W.Chang, J.-L.Chien, Y.-L.Hu, N.-T.Chan, N.-L.

(2005) J Biol Chem 280: 42356-42363

  • DOI: https://doi.org/10.1074/jbc.M506843200
  • Primary Citation of Related Structures:  
    2D27, 2D28

  • PubMed Abstract: 

    Secretion of fully folded extracellular proteins across the outer membrane of Gram-negative bacteria is mainly assisted by the ATP-dependent type II secretion system (T2SS). Depending on species, 12-15 proteins are usually required for the function of T2SS by forming a trans-envelope multiprotein secretion complex. Here we report crystal structures of an essential component of the Xanthomonas campestris T2SS, the 21-kDa N-terminal domain of cytosolic secretion ATPase XpsE (XpsEN), in two conformational states. By mediating interaction between XpsE and the cytoplasmic membrane protein XpsL, XpsEN anchors XpsE to the membrane-associated secretion complex to allow the coupling between ATP utilization and exoprotein secretion. The structure of XpsEN observed in crystal form P4(3)2(1)2 is composed of a 90-residue alpha/beta sandwich core domain capped by a 62-residue N-terminal helical region. The core domain exhibits structural similarity with the NifU-like domain, suggesting that XpsE(N) may be involved in the regulation of XpsE ATPase activity. Surprisingly, although a similar core domain structure was observed in crystal form I4(1)22, the N-terminal 36 residues of the helical region undergo a large structural rearrangement. Deletion analysis indicates that these residues are required for exoprotein secretion by mediating the XpsE/XpsL interaction. Site-directed mutagenesis study further suggests the more compact conformation observed in the P4(3)2(1)2 crystal likely represents the XpsL binding-competent state. Based on these findings, we speculate that XpsE might function in T2SS by cycling between two conformational states. As a closely related protein to XpsE, secretion ATPase PilB may function similarly in the type IV pilus assembly.

  • Organizational Affiliation

    Institute of Biochemistry, College of Life Sciences, National Chung Hsing University, Taichung City 402, Taiwan.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
type II secretion ATPase XpsEA [auth C]149Xanthomonas campestrisMutation(s): 4 
Gene Names: xpsE
Find proteins for P31742 (Xanthomonas campestris pv. campestris (strain ATCC 33913 / DSM 3586 / NCPPB 528 / LMG 568 / P 25))
Explore P31742 
Go to UniProtKB:  P31742
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP31742
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on CAC

Download Ideal Coordinates CCD File 
C2 H6 As O2
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on MSE
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.189 
  • R-Value Observed: 0.192 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 55.914α = 90
b = 55.914β = 90
c = 104.813γ = 90
Software Package:
Software NamePurpose
PDB_EXTRACTdata extraction
HKL-2000data reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-09-20
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 1.3: 2021-11-10
    Changes: Database references, Derived calculations