T. potens IscR

Experimental Data Snapshot

  • Resolution: 1.60 Å
  • R-Value Free: 0.220 
  • R-Value Work: 0.202 
  • R-Value Observed: 0.203 

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The Unique Regulation of Iron-Sulfur Cluster Biogenesis in a Gram-Positive Bacterium.

Santos, J.A.Alonso-Garcia, N.Macedo-Ribeiro, S.Pereira, P.J.B.

(2014) Proc Natl Acad Sci U S A 111: E2251

  • DOI: https://doi.org/10.1073/pnas.1322728111
  • Primary Citation of Related Structures:  
    4CHU, 4CIC

  • PubMed Abstract: 

    Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators.

  • Organizational Affiliation

    Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, 4150-180 Porto, Portugal; andInstituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, 4050-313 Porto, Portugal.

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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
153Thermincola potens JRMutation(s): 3 
Find proteins for D5X843 (Thermincola potens (strain JR))
Explore D5X843 
Go to UniProtKB:  D5X843
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupD5X843
Sequence Annotations
  • Reference Sequence

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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
HEXA-ALANINE PEPTIDEC [auth Q]6synthetic constructMutation(s): 0 
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.60 Å
  • R-Value Free: 0.220 
  • R-Value Work: 0.202 
  • R-Value Observed: 0.203 
  • Space Group: P 41
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 53.585α = 90
b = 53.585β = 90
c = 118.382γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
XSCALEdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-05-28
    Type: Initial release
  • Version 1.1: 2014-06-04
    Changes: Database references
  • Version 1.2: 2014-06-25
    Changes: Database references
  • Version 1.3: 2024-05-08
    Changes: Data collection, Database references, Derived calculations, Other