Iron uptake and increased intracellular enzyme activity follow host lactoferrin binding by Trichomonas vaginalis receptors

Journal Article · Wed Aug 01 00:00:00 EDT 1984 · J. Exp. Med.; (United States)

DOI:https://doi.org/10.1084/jem.160.2.398· OSTI ID:6303450

Peterson, K M; Alderete, J F

Lactoferrin acquisition and iron uptake by pathogenic Trichomonas vaginalis was examined. Saturation binding kinetics were obtained for trichomonads using increasing amounts of radioiodinated lactoferrin, while no significant binding by transferrin under similar conditions was achieved. Only unlabeled lactoferrin successfully and stoichiometrically competed with 125I-labeled lactoferrin binding. Time course studies showed maximal lactoferrin binding by 30 min at 37 degrees C. Data suggest no internalization of bound lactoferrin. The accumulation of radioactivity in supernatants after incubation of T. vaginalis with 125I-labeled lactoferrin and washing in PBS suggested the presence of low affinity sites for this host macromolecule. Scatchard analysis indicated the presence of 90,000 receptors per trichomonad with an apparent Kd of 1.0 microM. Two trichomonad lactoferrin binding proteins were identified by affinity chromatography and immunoprecipitation of receptor-ligand complexes. A 30-fold accumulation of iron was achieved using 59Fe-lactoferrin when compared to the steady state concentration of bound lactoferrin. The activity of pyruvate/ferrodoxin oxidoreductase, an enzyme involved in trichomonal energy metabolism, increased more than sixfold following exposure of the parasites to lactoferrin, demonstrating a biologic response to the receptor-mediated binding of lactoferrin. These data suggest that T. vaginalis possesses specific receptors for biologically relevant host proteins and that these receptors contribute to the metabolic processes of the parasites.

• Research Organization: Univ. of Texas Health Science Center, San Antonio
• OSTI ID: 6303450
• Journal Information: J. Exp. Med.; (United States), Journal Name: J. Exp. Med.; (United States) Vol. 160:2; ISSN JEMEA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMICAL BONDS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
ENZYME ACTIVITY
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
IRON
IRON 59
IRON ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
METALS
MICROORGANISMS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
RECEPTORS
TRACER TECHNIQUES
TRANSITION ELEMENTS
UPTAKE