Characterization of pit, a Streptococcus pneumoniae iron uptake ABC transporter

Infect Immun. 2002 Aug;70(8):4389-98. doi: 10.1128/IAI.70.8.4389-4398.2002.


Bacteria frequently have multiple mechanisms for acquiring iron, an essential micronutrient, from the environment. We have identified a four-gene Streptococcus pneumoniae operon, named pit, encoding proteins with similarity to components of a putative Brachyspira hyodysenteriae iron uptake ABC transporter, Bit. An S. pneumoniae strain containing a defined mutation in pit has impaired growth in medium containing the iron chelator ethylenediamine di-o-hydroxyphenylacetic acid, reduced sensitivity to the iron-dependent antibiotic streptonigrin, and impaired virulence in a mouse model of S. pneumoniae systemic infection. Furthermore, addition of a mutation in pit to a strain containing mutations in the two previously described S. pneumoniae iron uptake ABC transporters, piu and pia, resulted in a strain with impaired growth in two types of iron-deficient medium, a high degree of resistance to streptonigrin, and a reduced rate of iron uptake. Comparison of the susceptibilities to streptonigrin of the individual pit, piu, and pia mutant strains and comparison of the growth in iron-deficient medium and virulence of single and double mutant strains suggest that pia is the dominant iron transporter during in vitro and in vivo growth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / genetics*
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins / genetics*
  • Chlorides
  • Culture Media
  • Ferric Compounds / pharmacokinetics
  • Gene Expression Regulation, Bacterial
  • Iron / metabolism*
  • Iron-Binding Proteins
  • Mutagenesis
  • Operon*
  • Periplasmic Binding Proteins
  • Sequence Analysis, DNA
  • Streptococcus pneumoniae / drug effects
  • Streptococcus pneumoniae / genetics*
  • Streptococcus pneumoniae / growth & development
  • Streptococcus pneumoniae / pathogenicity
  • Streptonigrin / pharmacology
  • Transcription, Genetic
  • Virulence


  • ATP-Binding Cassette Transporters
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Chlorides
  • Culture Media
  • Ferric Compounds
  • Iron-Binding Proteins
  • Periplasmic Binding Proteins
  • Streptonigrin
  • Iron
  • ferric chloride