3GT6

Crystal Structure of the hspA from Xanthomonas axonopodis


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.201 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Crystal structures of Xanthomonas small heat shock protein provide a structural basis for an active molecular chaperone oligomer.

Hilario, E.Martin, F.J.Bertolini, M.C.Fan, L.

(2011) J Mol Biol 408: 74-86

  • DOI: 10.1016/j.jmb.2011.02.004
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • Small heat shock proteins (sHsps) are ubiquitous low-molecular-weight chaperones that prevent protein aggregation under cellular stresses. sHsps contain a structurally conserved α-crystallin domain (ACD) of about 100 amino acid residues flanked by va ...

    Small heat shock proteins (sHsps) are ubiquitous low-molecular-weight chaperones that prevent protein aggregation under cellular stresses. sHsps contain a structurally conserved α-crystallin domain (ACD) of about 100 amino acid residues flanked by varied N- and C-terminal extensions and usually exist as oligomers. Oligomerization is important for the biological functions of most sHsps. However, the active oligomeric states of sHsps are not defined yet. We present here crystal structures (up to 1.65 Å resolution) of the sHspA from the plant pathogen Xanthomonas (XaHspA). XaHspA forms closed or open trimers of dimers (hexamers) in crystals but exists predominantly as 36mers in solution as estimated by size-exclusion chromatography. The XaHspA monomer structures mainly consist of α-crystallin domain with disordered N- and C-terminal extensions, indicating that the extensions are flexible and not essential for the formation of dimers and 36mers. Under reducing conditions where α-lactalbumin (LA) unfolds and aggregates, XaHspA 36mers formed complexes with one LA per XaHspA dimer. Based on XaHspA dimer-dimer interactions observed in crystals, we propose that XaHspA 36mers have four possible conformations, but only XaHspA 36merB, which is formed by open hexamers in 12mer-6mer-6mer-12mer with protruding dimers accessible for substrate (unfolding protein) binding, can bind to 18 reduced LA molecules. Together, our results unravel the structural basis of an active sHsp oligomer.


    Organizational Affiliation

    Department of Biochemistry, University of California, Riverside, 2482B Boyce Hall, Riverside, CA 92521-0123, USA.



Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Low molecular weight heat shock protein
A, B
103Xanthomonas citriMutation(s): 0 
Gene Names: hspA
Find proteins for Q8PNC2 (Xanthomonas axonopodis pv. citri (strain 306))
Go to UniProtKB:  Q8PNC2
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.201 
  • Space Group: H 3
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 128.59α = 90
b = 128.59β = 90
c = 55.29γ = 120
Software Package:
Software NamePurpose
MOSFLMdata reduction
PHASERphasing
REFMACrefinement
PDB_EXTRACTdata extraction
HKL-2000data collection
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-02-16
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance