1R1T

Crystal structure of the cyanobacterial metallothionein repressor SmtB in the apo-form


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.219 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

A metal-ligand-mediated intersubunit allosteric switch in related SmtB/ArsR zinc sensor proteins.

Eicken, C.Pennella, M.A.Chen, X.Koshlap, K.M.VanZile, M.L.Sacchettini, J.C.Giedroc, D.P.

(2003) J Mol Biol 333: 683-695

  • DOI: 10.1016/j.jmb.2003.09.007
  • Primary Citation of Related Structures:  
    1R1V, 1R1U, 1R1T, 1R23, 1R22

  • PubMed Abstract: 
  • The origin of metal ion selectivity by members of the SmtB/ArsR family of bacterial metal-sensing transcriptional repressors and the mechanism of negative allosteric regulation of DNA binding is poorly understood. Here, we report that two homologous ...

    The origin of metal ion selectivity by members of the SmtB/ArsR family of bacterial metal-sensing transcriptional repressors and the mechanism of negative allosteric regulation of DNA binding is poorly understood. Here, we report that two homologous zinc sensors, Staphylococcus aureus CzrA and cyanobacterial SmtB, are "winged" helix homodimeric DNA-binding proteins that bind Zn(II) to a pair of tetrahedral, interhelical binding sites, with two ligands derived from the alpha5 helix of one subunit, Asp84 O(delta1) (Asp104 in SmtB), His86 N(delta1) (His106), and two derived from the alpha5 helix of the other, His97' N(delta1) (His117') and His100' N(epsilon2) (Glu120'). Formation of the metal chelate drives a quaternary structural switch mediated by an intersubunit hydrogen-binding network that originates with the non-liganding N(epsilon2) face of His97 in CzrA (His117 in SmtB) that stabilizes a low-affinity, DNA-binding conformation. The structure of the Zn(1) SmtB homodimer shows that both metal-binding sites of the dimer must be occupied for the quaternary structural switch to occur. Thus, a critical zinc-ligating histidine residue obligatorily couples formation of the metal-sensing coordination chelate to changes in the conformation and dynamics of the putative DNA-binding helices.


    Organizational Affiliation

    Department of Biochemistry and Biophysics, Center for Structural Biology, Texas A&M University, College Station, TX 77843-2128, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Transcriptional repressor smtBAB122Synechococcus elongatus PCC 7942 = FACHB-805Mutation(s): 0 
Gene Names: smtBSynpcc7942_1291
Find proteins for P30340 (Synechococcus elongatus (strain PCC 7942 / FACHB-805))
Explore P30340 
Go to UniProtKB:  P30340
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.219 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 37.24α = 90
b = 69.722β = 95.84
c = 43.221γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement
CNSphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-05-18
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance