Siderophore activity of myo-inositol hexakisphosphate in Pseudomonas aeruginosa

Anthony W. Smith, David R. Poyner, H.K. Hughes, Peter A. Lambert

Research output: Contribution to journalArticlepeer-review


Myo-Inositol hexakisphosphate (InsP6), which is found in soil and most, if not all, plant and animal cells, has been estimated to have an affinity for Fe3+ in the range of 10(25) to 10(30) M-1. In this report, we demonstrate that the Fe-InsP6 complex has siderophore activity and is able to reverse the iron-restricted growth inhibition of Pseudomonas aeruginosa by ethylene diamine di(o-hydroxyphenyl)acetic acid. With 55Fe-InsP6 in transport studies, iron uptake is strongly iron regulated, being repressed after growth in iron-replete conditions and inhibited by treatment with potassium cyanide and carbonyl cyanide m-chlorophenylhydrazone. The kinetics of iron transport revealed a Km of 100 nM. Self-displacement of binding of [3H]InsP6 to isolated membranes by InsP6 revealed a single class of binding sites (Kd = 143 +/- 6 nM; Hill coefficient, 1.1 +/- 0.1). The binding of [3H]InsP6 to membranes was not dependent on whether cells had been grown under conditions of high or low iron concentrations. We believe that this is the first report of inositol polyphosphate activity in prokaryotic cells.
Original languageEnglish
Pages (from-to)3455-3459
Number of pages5
JournalJournal of Bacteriology
Issue number12
Publication statusPublished - 14 Jun 1994


  • binding
  • competitive
  • cell division
  • cell membrane
  • dose-response relationship
  • drug
  • ferric compounds
  • iron phytic acid
  • pseudomonas aeruginosa
  • siderophores
  • time factors


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