Examination of an inducible expression system for limiting iron availability during Chlamydia trachomatis infection

Microbes Infect. 2007 Jul;9(8):947-53. doi: 10.1016/j.micinf.2007.03.017. Epub 2007 Apr 7.

Abstract

The obligate intracellular bacterium Chlamydia trachomatis requires iron in order to complete its developmental cycle. Addition of an iron-chelating drug, Desferal (deferoxamine mesylate), to infected cell culture causes Chlamydia to enter persistence. Here, we explore the ability of a stably-transfected cell line with inducible over-expression of the eukaryotic iron efflux protein ferroportin to starve C. trachomatis serovar E for iron. Ferroportin-induced iron removal is perhaps a more direct method of removing iron from the intracellular compartment versus exposure to an exogenous chemical chelator. Following induction, ferroportin-green fluorescent protein (Fpn-GFP) was detected in the plasma membrane, and cells expressing Fpn-GFP remained viable throughout the timescale required for Chlamydia to complete its developmental cycle. Following Fpn-GFP induction in infected cells, chlamydial infectivity remained unchanged, indicating chlamydiae were not in persistence. Ferritin levels indicate only a small decrease in cellular iron following Fpn-GFP expression relative to cultures exposed to Desferal. These data indicate that expression of Fpn-GFP in chlamydiae-infected cells is not capable of reducing iron below the threshold concentration needed to cause chlamydiae to enter persistence.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism*
  • Cell Line
  • Chlamydia trachomatis / growth & development
  • Chlamydia trachomatis / metabolism*
  • Chlamydia trachomatis / physiology
  • Chlamydia trachomatis / ultrastructure
  • Ferritins / metabolism
  • Gene Expression Regulation, Bacterial*
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Humans
  • Iron / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Time Factors

Substances

  • Cation Transport Proteins
  • Recombinant Proteins
  • metal transporting protein 1
  • Green Fluorescent Proteins
  • Ferritins
  • Iron