Crystal structure of ZnuA

Experimental Data Snapshot

  • Resolution: 1.90 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.172 
  • R-Value Observed: 0.172 

wwPDB Validation   3D Report Full Report

This is version 1.3 of the entry. See complete history


Structural Determinants of Metal Specificity in the Zinc Transport Protein ZnuA from Synechocystis 6803.

Banerjee, S.Wei, B.Bhattacharyya-Pakrasi, M.Pakrasi, H.B.Smith, T.J.

(2003) J Mol Biol 333: 1061-1069

  • DOI: https://doi.org/10.1016/j.jmb.2003.09.008
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    A number of bacterial metal transporters belong to the cluster 9 family of ABC transporters. The residues in the periplasmic domain thought to be involved in metal binding seem highly conserved and yet the transporters have varying metal specificity. To solve this seeming paradox and ascertain how metal specificity is exacted, the structure of ZnuA, the periplasmic domain of a zinc transporter from Synechocystis 6803, has been determined to a resolution of 1.9A. In previously determined structures of homologous proteins, four residues chelate the bound metal. From sequence alignments of the cluster 9 metal transporters, the fourth residue in this metal-binding site, an aspartate, is also present in the appropriate position in the ZnuA sequence. However, this result is misleading, since our structural data indicate that zinc binds via only three histidine residues and the aspartate is replaced by a large hydrophobic cavity. We propose that ZnuA binds zinc over manganese by providing only three ligating residues. ZnuA has a highly charged and mobile loop that protrudes from the protein in the vicinity of the metal-binding site. Similar loops are found in other types of zinc transporters but not manganese transporters. Therefore, we propose that the function of this domain is to act as a zinc chaperone to facilitate acquisition. Therefore, while Mn2+ transporters can bind Zn2+ in vitro they may not be able to acquire it in vivo without this structure because of the low concentration of free Zn2+.

  • Organizational Affiliation

    Donald Danforth Plant Science Center, 975 North Warson Road, St Louis, MO 63132, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
periplasmic binding protein component of an ABC type zinc uptake transporter
A, B
291Synechocystis sp. PCC 6803Mutation(s): 0 
Find proteins for P73085 (Synechocystis sp. (strain PCC 6803 / Kazusa))
Explore P73085 
Go to UniProtKB:  P73085
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP73085
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on ZN

Download Ideal Coordinates CCD File 
C [auth A],
D [auth B]
Experimental Data & Validation

Experimental Data

  • Resolution: 1.90 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.172 
  • R-Value Observed: 0.172 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 64.99α = 90
b = 78.3β = 118.32
c = 68.4γ = 90
Software Package:
Software NamePurpose
PROTEUM PLUSdata reduction
PROTEUM PLUSdata scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-11-04
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.3: 2024-02-14
    Changes: Data collection, Database references, Derived calculations