Iron acquisition with the natural siderophore enantiomers pyochelin and enantio-pyochelin in Pseudomonas species

Biometals. 2011 Jun;24(3):513-22. doi: 10.1007/s10534-010-9399-9. Epub 2010 Dec 25.


The bacterial siderophore pyochelin is composed of salicylate and two cysteine-derived heterocycles, the second of which is modified by reduction and N-methylation during biosynthesis. In Pseudomonas aeruginosa, the first cysteine residue is converted to its D-isoform during thiazoline ring formation, whereas the second cysteine remains in its L-configuration. Stereochemistry is opposite in the Pseudomonas fluorescens siderophore enantio-pyochelin, in which the first ring originates from L-cysteine and the second ring from D-cysteine. Both siderophores promote growth of the producer organism during iron limitation and induce the expression of their biosynthesis genes by activating the transcriptional AraC-type regulator PchR. However, neither siderophore is functional as an iron carrier or as a transcriptional inducer in the other species, demonstrating that both processes are highly stereospecific. Stereospecificity of pyochelin/enantio-pyochelin-mediated iron uptake is ensured at two levels: (i) by the outer membrane siderophore receptors and (ii) by the cytosolic PchR regulators.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Amino Acid Sequence
  • Iron / chemistry*
  • Iron / metabolism*
  • Molecular Sequence Data
  • Molecular Structure
  • Oxidation-Reduction
  • Phenols / chemistry*
  • Phenols / metabolism
  • Pseudomonas / chemistry*
  • Pseudomonas / genetics
  • Pseudomonas / metabolism*
  • Sequence Alignment
  • Siderophores / chemistry*
  • Siderophores / genetics
  • Siderophores / metabolism
  • Stereoisomerism
  • Thiazoles / chemistry*
  • Thiazoles / metabolism


  • Phenols
  • Siderophores
  • Thiazoles
  • pyochelin
  • Iron