X-ray crystallography and isothermal titration calorimetry studies of the Salmonella zinc transporter ZntB

Structure. 2011 May 11;19(5):700-10. doi: 10.1016/j.str.2011.02.011.

Abstract

The ZntB Zn(2+) efflux system is important for maintenance of Zn(2+) homeostasis in Enterobacteria. We report crystal structures of ZntB cytoplasmic domains from Salmonella enterica serovar Typhimurium (StZntB) in dimeric and physiologically relevant homopentameric forms at 2.3 Å and 3.1 Å resolutions, respectively. The funnel-like structure is similar to that of the homologous Thermotoga maritima CorA Mg(2+) channel and a Vibrio parahaemolyticus ZntB (VpZntB) soluble domain structure. However, the central α7 helix forming the inner wall of the StZntB funnel is oriented perpendicular to the membrane instead of the marked angle seen in CorA or VpZntB. Consequently, the StZntB funnel pore is cylindrical, not tapered, which may represent an "open" form of the ZntB soluble domain. Our crystal structures and isothermal titration calorimetry data indicate that there are three Zn(2+) binding sites in the full-length ZntB, two of which could be involved in Zn(2+) transport.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Binding Sites
  • Calorimetry
  • Carrier Proteins / chemistry*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cation Transport Proteins / chemistry*
  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism
  • Cloning, Molecular
  • Crystallography, X-Ray
  • Escherichia coli
  • Ion Transport
  • Models, Molecular
  • Protein Multimerization
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Recombinant Proteins / chemistry*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Salmonella Infections / virology
  • Salmonella typhimurium / chemistry*
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / metabolism
  • Thermotoga maritima / chemistry
  • Thermotoga maritima / metabolism
  • Vibrio parahaemolyticus / chemistry
  • Vibrio parahaemolyticus / metabolism
  • Zinc / metabolism*

Substances

  • Bacterial Proteins
  • Carrier Proteins
  • Cation Transport Proteins
  • Recombinant Proteins
  • zinc-binding protein
  • Zinc

Associated data

  • PDB/3NVO
  • PDB/3NWI