Crystal structure of IscS from Mycobacterium tuberculosis

Experimental Data Snapshot

  • Resolution: 2.59 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.189 

Starting Model: experimental
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The cysteine desulfurase IscS of Mycobacterium tuberculosis is involved in iron-sulfur cluster biogenesis and oxidative stress defence.

Rybniker, J.Pojer, F.Marienhagen, J.Kolly, G.S.Chen, J.M.van Gumpel, E.Hartmann, P.Cole, S.T.

(2014) Biochem J 459: 467-478

  • DOI: https://doi.org/10.1042/BJ20130732
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The complex multiprotein systems for the assembly of protein-bound iron-sulfur (Fe-S) clusters are well defined in Gram-negative model organisms. However, little is known about Fe-S cluster biogenesis in other bacterial species. The ISC (iron-sulfur cluster) operon of Mycobacterium tuberculosis lacks several genes known to be essential for the function of this system in other organisms. However, the cysteine desulfurase IscSMtb (Rv number Rv3025c; Mtb denotes M. tuberculosis) is conserved in this important pathogen. The present study demonstrates that deleting iscSMtb renders the cells microaerophilic and hypersensitive to oxidative stress. Moreover, the ∆iscSMtb mutant shows impaired Fe-S cluster-dependent enzyme activity, clearly indicating that IscSMtb is associated with Fe-S cluster assembly. An extensive interaction network of IscSMtb with Fe-S proteins was identified, suggesting a novel mechanism of sulfur transfer by direct interaction with apoproteins. Interestingly, the highly homologous IscS of Escherichia coli failed to complement the ∆iscSMtb mutant and showed a less diverse protein-interaction profile. To identify a structural basis for these observations we determined the crystal structure of IscSMtb, which mirrors adaptations made in response to an ISC operon devoid of IscU-like Fe-S cluster scaffold proteins. We conclude that in M. tuberculosis IscS has been redesigned during evolution to compensate for the deletion of large parts of the ISC operon.

  • Organizational Affiliation

    *Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cysteine desulfurase
A, B, C, D
404Mycobacterium tuberculosisMutation(s): 0 
Gene Names: iscSMT3109Rv3025c
Find proteins for P9WQ71 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Explore P9WQ71 
Go to UniProtKB:  P9WQ71
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP9WQ71
Sequence Annotations
  • Reference Sequence
Small Molecules
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on LLP
A, B, C, D
Experimental Data & Validation

Experimental Data

  • Resolution: 2.59 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.189 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 66.814α = 94.54
b = 78.131β = 104.71
c = 92.774γ = 98.57
Software Package:
Software NamePurpose
XDSdata scaling
XDSdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-02-26
    Type: Initial release
  • Version 1.1: 2014-04-23
    Changes: Database references
  • Version 1.2: 2023-09-20
    Changes: Data collection, Database references, Derived calculations, Refinement description
  • Version 1.3: 2023-12-06
    Changes: Data collection