The crystal structure of Sph at 0.8A

Experimental Data Snapshot

  • Resolution: 0.80 Å
  • R-Value Free: 0.166 
  • R-Value Work: 0.146 
  • R-Value Observed: 0.147 

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The crystal structures of the psychrophilic subtilisin S41 and the mesophilic subtilisin Sph reveal the same calcium-loaded state.

Almog, O.Gonzalez, A.Godin, N.de Leeuw, M.Mekel, M.J.Klein, D.Braun, S.Shoham, G.Walter, R.L.

(2009) Proteins 74: 489-496

  • DOI: https://doi.org/10.1002/prot.22175
  • Primary Citation of Related Structures:  
    2GKO, 2IXT, 3D43

  • PubMed Abstract: 

    We determine and compare the crystal structure of two proteases belonging to the subtilisin superfamily: S41, a cold-adapted serine protease produced by Antarctic bacilli, at 1.4 A resolution and Sph, a mesophilic serine protease produced by Bacillus sphaericus, at 0.8 A resolution. The purpose of this comparison was to find out whether multiple calcium ion binding is a molecular factor responsible for the adaptation of S41 to extreme low temperatures. We find that these two subtilisins have the same subtilisin fold with a root mean square between the two structures of 0.54 A. The final models for S41 and Sph include a calcium-loaded state of five ions bound to each of these two subtilisin molecules. None of these calcium-binding sites correlate with the high affinity known binding site (site A) found for other subtilisins. Structural analysis of the five calcium-binding sites found in these two crystal structures indicate that three of the binding sites have two side chains of an acidic residue coordinating the calcium ion, whereas the other two binding sites have either a main-chain carbonyl, or only one acidic residue side chain coordinating the calcium ion. Thus, we conclude that three of the sites are of high affinity toward calcium ions, whereas the other two are of low affinity. Because Sph is a mesophilic subtilisin and S41 is a psychrophilic subtilisin, but both crystal structures were found to bind five calcium ions, we suggest that multiple calcium ion binding is not responsible for the adaptation of S41 to low temperatures.

  • Organizational Affiliation

    Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University, Beer Sheva 84105, Israel. almogo@bgu.ac.il

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
310Lysinibacillus sphaericusMutation(s): 0 
Find proteins for Q9S3L6 (Lysinibacillus sphaericus)
Explore Q9S3L6 
Go to UniProtKB:  Q9S3L6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9S3L6
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 0.80 Å
  • R-Value Free: 0.166 
  • R-Value Work: 0.146 
  • R-Value Observed: 0.147 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.088α = 90
b = 62.668β = 95.47
c = 84.874γ = 90
Software Package:
Software NamePurpose
SHELXmodel building
MAR345dtbdata collection
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

  • Released Date: 2009-04-28 
  • Deposition Author(s): Almog, O.

Revision History  (Full details and data files)

  • Version 1.0: 2009-04-28
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2017-10-25
    Changes: Refinement description, Source and taxonomy
  • Version 1.3: 2023-08-30
    Changes: Data collection, Database references, Derived calculations, Refinement description