HspA from Thermosynechococcus vulcanus in the presence of 2M urea with initial stages of denaturation

Experimental Data Snapshot

  • Resolution: 2.29 Å
  • R-Value Free: 0.342 
  • R-Value Work: 0.280 

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Biophysical and structural characterization of the small heat shock protein HspA from Thermosynechococcus vulcanus in 2 M urea.

Ghosh, S.Salama, F.Dines, M.Lahav, A.Adir, N.

(2019) Biochim Biophys Acta Proteins Proteom 1867: 442-452

  • DOI: https://doi.org/10.1016/j.bbapap.2018.12.011
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Small heat shock proteins (sHSPs) belong to the superfamily of molecular chaperones. They prevent aggregation of partially unfolded or misfolded client proteins, providing protection to organisms under stress conditions. Here, we report the biophysical and structural characterization of a small heat shock protein (HspA) from a thermophilic cyanobacterium Thermosynechococcus vulcanus in the presence of 2 M urea. HspA has been shown to be important for the protection of Photosystem II and the Phycobilisome antenna complex at elevated temperatures. Heterologously expressed HspA requires the presence of 1-2 M urea to maintain its solubility at concentrations required for most characterization methods. Spectroscopic studies reveal the presence of the β-sheet structure and intactness of the tertiary fold in HspA. In vitro assays show that the HspA maintains chaperone-like activity in protecting soluble proteins from thermal aggregation. Chromatography and electron microscopy show that the HspA exists as a mixture of oligomeric forms in the presence of 2 M urea. HspA was successfully crystallized only in the presence of 2 M urea. The crystal structure of HspA shows urea-induced loss of about 30% of the secondary structure without major alteration in the tertiary structure of the protein. The electron density maps reveal changes in the hydrogen bonding network which we attribute to the presence of urea. The crystal structure of HspA demonstrates a mixture of both direct interactions between urea and protein functionalities and interactions between urea and the surrounding solvent that indirectly affect the protein, which are in accordance with previously published studies.

  • Organizational Affiliation

    Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Technion City, Haifa 32000, Israel.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
99Thermostichus vulcanusMutation(s): 0 
Gene Names: hspA
Find proteins for O82825 (Thermostichus vulcanus)
Explore O82825 
Go to UniProtKB:  O82825
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO82825
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on URE

Download Ideal Coordinates CCD File 
AA [auth B]
BA [auth B]
C [auth A]
CA [auth B]
D [auth A]
AA [auth B],
BA [auth B],
C [auth A],
CA [auth B],
D [auth A],
DA [auth B],
E [auth A],
EA [auth B],
F [auth A],
FA [auth B],
G [auth A],
GA [auth B],
H [auth A],
HA [auth B],
I [auth A],
IA [auth B],
J [auth A],
JA [auth B],
K [auth A],
KA [auth B],
L [auth A],
LA [auth B],
M [auth A],
MA [auth B],
N [auth A],
NA [auth B],
O [auth A],
OA [auth B],
P [auth A],
PA [auth B],
Q [auth A],
QA [auth B],
R [auth A],
RA [auth B],
S [auth B],
SA [auth B],
T [auth B],
TA [auth B],
U [auth B],
V [auth B],
W [auth B],
X [auth B],
Y [auth B],
Z [auth B]
C H4 N2 O
Experimental Data & Validation

Experimental Data

  • Resolution: 2.29 Å
  • R-Value Free: 0.342 
  • R-Value Work: 0.280 
  • Space Group: I 41
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 88.65α = 90
b = 88.65β = 90
c = 114.3γ = 90
Software Package:
Software NamePurpose
MOSFLMdata collection
SCALAdata scaling
PDB_EXTRACTdata extraction
SCALAdata reduction

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
ISFIsrael1045/06, 1576/12 and 843/16

Revision History  (Full details and data files)

  • Version 1.0: 2018-10-17
    Type: Initial release
  • Version 1.1: 2019-04-24
    Changes: Data collection, Database references
  • Version 1.2: 2024-01-17
    Changes: Data collection, Database references, Refinement description