A Trichomonas vaginalis 120 kDa protein with identity to hydrogenosome pyruvate:ferredoxin oxidoreductase is a surface adhesin induced by iron

Abstract

SummaryTrichomonas vaginalis , a human sexually transmitted protozoan, relies on adherence to the vaginal epithelium for colonization and maintenance of infection in the host. Thus, adherence molecules play a fundamental role in the trichomonal infection. Here, we show the identification and characterization of a 120 kDa surface glycoprotein (AP120) induced by iron, which participates in cytoadherence. AP120 is synthesized by the parasite when grown in 250 m m m m M iron medium. Antibodies to AP120 and the electroeluted AP120 inhibited parasite adherence in a concentration-dependent manner, demonstrating its participation in cytoadherence. In addition, a protein of 130 kDa was detected on the surface of HeLa cells as the putative receptor for AP120. By peptide matrixassisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), the AP120 adhesin showed homology with a hydrogenosomal enzyme, the pyruvate:ferredoxin oxidoreductase (PFO) encoded by the pfoa gene. This homology was confirmed by immunoblot and indirect immunofluorescence assays with an antibody to the carboxyterminus region of the Entamoeba histolytica PFO. Reverse transcription polymerase chain reaction (RT-PCR) assays showed that a pfoa -like gene was better transcribed in trichomonads grown in iron-rich medium. In conclusion, the homology of AP120 to PFO suggests that this novel adhesin induced by iron could be an example of moonlighting protein in T. vaginalis .

Regulation of Nuclear Translocation of the Myb1 Transcription Factor by TvCyclophilin 1 in the Protozoan Parasite Trichomonas vaginalis

“…The organism utilizes fermentative metabolism for energy production, which primarily takes place in the hydrogenosomes (2). Intriguingly, iron overloading, toxic to most organisms, is beneficial to the parasite by increasing the expression of many hydrogenosomal enzymes and promoting its cytoadherence to human vaginal epithelial cells (7)(8)(9). Several hydrogenosomal enzymes have previously been shown to be expressed on cell surfaces and mediate the cytoadherence of T. vaginalis when its growth medium was supplied with an excessive amount of iron (7,8,10).…”

“…Intriguingly, iron overloading, toxic to most organisms, is beneficial to the parasite by increasing the expression of many hydrogenosomal enzymes and promoting its cytoadherence to human vaginal epithelial cells (7)(8)(9). Several hydrogenosomal enzymes have previously been shown to be expressed on cell surfaces and mediate the cytoadherence of T. vaginalis when its growth medium was supplied with an excessive amount of iron (7,8,10). Although the secondary roles of these hydrogenosomal enzymes remain arguable, biochemical and genetic evidence suggests that a 65-kDa malic enzyme, referred to as AP65 and encoded by the ap65-1 gene, is likely involved in parasitic cytoadherence to human vaginal epithelial cells (11)(12)(13).…”

Iron-Inducible Nuclear Translocation of a Myb3 Transcription Factor in the Protozoan Parasite Trichomonas vaginalis

“…A number of parasitic virulence factors, especially those inducible under iron repletion (1,2,5,16,25), were identified decades ago. Since the parasite persistently colonizes the human urogenital tract without a dormant cyst stage, its cytoadherence to vaginal epithelial cells is crucial for its survival.…”

The Glycolytic Enzyme Triosephosphate Isomerase of Trichomonas vaginalis Is a Surface-Associated Protein Induced by Glucose That Functions as a Laminin- and Fibronectin-Binding Protein

“…Total protein extracts from T. vaginalis (2 ϫ 10 7 ) grown under GR, NG, or HG conditions were obtained using a previously described method (8,9). Briefly, the parasites were resuspended in 500 l of NET (50 mM Tris-HCl, 150 mM NaCl and 5 mM EDTA) buffer (pH 7.4) in the presence of proteinase inhibitors (1 mM N␣-p-tosyl-L-lysine chloromethyl ketone [TLCK] and 0.2 mM leupeptin), lysed with 0.5% deoxycholic acid (DOC) for 20 min at 4°C, and then brought up to a final volume of 1 ml with TDSET (10 mM Tris-Cl [pH 7.8], 0.2% DOC, 0.1% SDS, 10 mM EDTA, and 1% Triton X-100) buffer.…”

“…For example, several hydrogenosomal enzymes (pyruvate:ferredoxin oxidoreductase [PFO]/ AP120, malic enzyme/AP65, and ␣-and ␤-succinyl-coenzyme A [CoA] synthetase subunits/AP33 and AP51, respectively) can switch functions, depending on their cellular localizations, acting as metabolic enzymes in the hydrogenosome and cytoplasm or as adhesins on the parasite surface (8)(9)(10). Importantly, iron and cellular contact positively regulate the level of adherence by directly increasing adhesin synthesis (10).…”