Binding of fibronectin by Trichomonas vaginalis is influenced by iron and calcium.

We have reported that Trichomonas vaginalis, the causative agent of the most common, non-viral sexually transmitted disease, bound to cover slips coated with fibronectin (FN) (Crouch & Alderete, Microbiol 1999 145: 2835-43). In this study, we extend that observation by showing that FN binding is specific, and we present data on the requirements of FN binding by T. vaginalis. Immunofluorescence and immuno-gold labelling readily detected FN throughout the trichomonal surface. Parasites bound to(125)I-labelled FN in a time- and concentration-dependent fashion. In the absence of protease inhibitor, iodinated FN was released from the trichomonad surface. Unlabelled FN specifically competed for binding in a concentration-dependent fashion with the(125)I-labelled FN. Interestingly, the amount of FN bound by T. vaginalis organisms was dependent on iron. High-iron-grown trichomonads acquired lower numbers of molecules but with 10-fold higher affinity than low-iron-grown organisms. Further, we show that for iron-replete organisms, calcium (Ca(2+)) at physiological levels increased amounts of bound FN. The increase in binding was rapid, occurring within 5 min of Ca(2+)addition, and required de novo protein synthesis. Co-incubation of live parasites with Ca(2+)in the presence of FN was necessary to increase the amount of FN bound. Treatment of trichomonads with okadaic acid, but not other phosphatase inhibitors, resulted in a 50% decrease in binding of FN, regardless of the presence of Ca(2+), suggesting a role for phosphatase in FN association. These results indicate that depending on the iron status of T. vaginalis organisms in vivo, Ca(2+)may influence trichomonad recognition and binding to FN during host parasitism.
AuthorsM L Crouch, M Benchimol, J F Alderete
JournalMicrobial pathogenesis (Microb Pathog) Vol. 31 Issue 3 Pg. 131-44 (Sep 2001) ISSN: 0882-4010 [Print] England
PMID11500098 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
CopyrightCopyright 2001 Academic Press.
Chemical References
  • Fibronectins
  • Protease Inhibitors
  • Okadaic Acid
  • Iron
  • Phosphoprotein Phosphatases
  • Cysteine Endopeptidases
  • Calcium
  • Animals
  • Binding, Competitive (drug effects)
  • Calcium (pharmacology)
  • Cell Adhesion (drug effects)
  • Cysteine Endopeptidases (metabolism)
  • Dose-Response Relationship, Drug
  • Female
  • Fibronectins (metabolism, pharmacology)
  • Fluorescent Antibody Technique
  • Glass
  • Humans
  • Iron (pharmacology)
  • Microscopy, Immunoelectron
  • Okadaic Acid (pharmacology)
  • Phosphoprotein Phosphatases (antagonists & inhibitors, metabolism)
  • Protease Inhibitors (pharmacology)
  • Protein Binding (drug effects)
  • Protein Biosynthesis
  • Substrate Specificity
  • Trichomonas Vaginitis (microbiology)
  • Trichomonas vaginalis (cytology, drug effects, enzymology, metabolism)

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