1JJD

NMR structure of the Cyanobacterial Metallothionein SmtA


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 500 
  • Conformers Submitted: 
  • Selection Criteria: DIANA target function 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

A metallothionein containing a zinc finger within a four-metal cluster protects a bacterium from zinc toxicity.

Blindauer, C.A.Harrison, M.D.Parkinson, J.A.Robinson, A.K.Cavet, J.S.Robinson, N.J.Sadler, P.J.

(2001) Proc.Natl.Acad.Sci.USA 98: 9593-9598

  • DOI: 10.1073/pnas.171120098

  • PubMed Abstract: 
  • Zinc is essential for many cellular processes, including DNA synthesis, transcription, and translation, but excess can be toxic. A zinc-induced gene, smtA, is required for normal zinc-tolerance in the cyanobacterium Synechococcus PCC 7942. Here we re ...

    Zinc is essential for many cellular processes, including DNA synthesis, transcription, and translation, but excess can be toxic. A zinc-induced gene, smtA, is required for normal zinc-tolerance in the cyanobacterium Synechococcus PCC 7942. Here we report that the protein SmtA contains a cleft lined with Cys-sulfur and His-imidazole ligands that binds four zinc ions in a Zn(4)Cys(9)His(2) cluster. The thiolate sulfurs of five Cys ligands provide bridges between the two ZnCys(4) and two ZnCys(3)His sites, giving two fused six-membered rings with distorted boat conformations. The inorganic core strongly resembles the Zn(4)Cys(11) cluster of mammalian metallothionein, despite different amino acid sequences, a different linear order of the ligands, and presence of histidine ligands. Also, SmtA contains elements of secondary structure not found in metallothioneins. One of the two Cys(4)-coordinated zinc ions in SmtA readily exchanges with exogenous metal ((111)Cd), whereas the other is inert. The thiolate sulfur ligands bound to zinc in this site are buried within the protein. Regions of beta-strand and alpha-helix surround the inert site to form a zinc finger resembling the zinc fingers in GATA and LIM-domain proteins. Eukaryotic zinc fingers interact specifically with other proteins or DNA and an analogous interaction can therefore be anticipated for prokaryotic zinc fingers. SmtA now provides structural proof for the existence of zinc fingers in prokaryotes, and sequences related to the zinc finger motif can be identified in several bacterial genomes.


    Organizational Affiliation

    Department of Chemistry, University of Edinburgh, United Kingdom.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
METALLOTHIONEIN
A
55Synechococcus elongatus (strain PCC 7942)Mutation(s): 0 
Gene Names: smtA
Find proteins for P30331 (Synechococcus elongatus (strain PCC 7942))
Go to UniProtKB:  P30331
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download SDF File 
Download CCD File 
A
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 500 
  • Conformers Submitted: 
  • Selection Criteria: DIANA target function 

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-08-22
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Source and taxonomy, Version format compliance