Characterization of a dipartite iron uptake system from uropathogenic Escherichia coli strain F11

J Biol Chem. 2011 Jul 15;286(28):25317-30. doi: 10.1074/jbc.M111.222745. Epub 2011 May 19.

Abstract

In the uropathogenic Escherichia coli strain F11, in silico genome analysis revealed the dicistronic iron uptake operon fetMP, which is under iron-regulated control mediated by the Fur regulator. The expression of fetMP in a mutant strain lacking known iron uptake systems improved growth under iron depletion and increased cellular iron accumulation. FetM is a member of the iron/lead transporter superfamily and is essential for iron uptake by the Fet system. FetP is a periplasmic protein that enhanced iron uptake by FetM. Recombinant FetP bound Cu(II) and the iron analog Mn(II) at distinct sites. The crystal structure of the FetP dimer reveals a copper site in each FetP subunit that adopts two conformations: CuA with a tetrahedral geometry composed of His(44), Met(90), His(97), and His(127), and CuB, a second degenerate octahedral geometry with the addition of Glu(46). The copper ions of each site occupy distinct positions and are separated by ∼1.3 Å. Nearby, a putative additional Cu(I) binding site is proposed as an electron source that may function with CuA/CuB displacement to reduce Fe(III) for transport by FetM. Together, these data indicate that FetMP is an additional iron uptake system composed of a putative iron permease and an iron-scavenging and potentially iron-reducing periplasmic protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Cation Transport Proteins* / chemistry
  • Cation Transport Proteins* / genetics
  • Cation Transport Proteins* / metabolism
  • Copper / chemistry
  • Copper / metabolism
  • Crystallography, X-Ray
  • Escherichia coli Proteins* / chemistry
  • Escherichia coli Proteins* / genetics
  • Escherichia coli Proteins* / metabolism
  • Gene Expression Regulation, Bacterial / physiology
  • Ion Transport / physiology
  • Iron / metabolism*
  • Manganese / chemistry
  • Manganese / metabolism
  • Operon / physiology
  • Periplasmic Proteins* / chemistry
  • Periplasmic Proteins* / genetics
  • Periplasmic Proteins* / metabolism
  • Protein Multimerization / physiology*
  • Protein Structure, Quaternary
  • Uropathogenic Escherichia coli* / chemistry
  • Uropathogenic Escherichia coli* / genetics
  • Uropathogenic Escherichia coli* / metabolism

Substances

  • Cation Transport Proteins
  • Escherichia coli Proteins
  • Periplasmic Proteins
  • Manganese
  • Copper
  • Iron

Associated data

  • PDB/3NRP
  • PDB/3NRQ