Cysteine peptidase expression in Trichomonas vaginalis isolates displaying high- and low-virulence phenotypes.

In the present study, we identified and characterized the cysteine peptidase (CP) profiles of Trichomonas vaginalis isolates exhibiting high- and low-virulence phenotypes using a combination of two-dimensional SDS-PAGE (2DE), tandem mass spectrometry (MS/MS), and data mining. Seven of the eight CPs identified belong to Clan CA, family C1, cathepsin L-like CP, and one belongs to Clan CD, family C13, asparaginyl endopeptidase-like CP. Quantitative and qualitative differences in CP expression were detected between the isolates. BLAST analysis followed by CLUSTAL alignment of amino acid sequences of differentially expressed CPs showed identity or high homology to previously described CP cDNA clones CP1, CP3, CP4, and to a secreted CP fraction of 30 kDa involved in apoptosis of vaginal epithelial cells. One- and two-dimensional-substrate gel analyses revealed the differential CP profiles between the isolates, indicating that the combination of zymography with 2DE and MS/MS might be a powerful experimental approach to map and identify active peptidases in T. vaginalis. Toxicity exerted upon HeLa cells by high- and low-virulence isolates was 98.3% and 31%, respectively. Pretreatment of parasites with specific Clan CA papain-like CP inhibitor l-3-carboxy-2,3-trans-epoxypropionyl-leucylamido(4-guanidino)butane (E-64) drastically reduced the cytotoxic effect to 21.7% and 0.8%, respectively, suggesting that T. vaginalis papain-like CPs are the main factors involved in the cellular damage.

Application of two-dimensional electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for proteomic analysis of the sexually transmitted parasite Trichomonas vaginalis.

Trichomonas vaginalis is a sexually transmitted protozoan parasite that infects the human urogenital tract causing trichomoniasis, a worldwide disease. In this work, a fresh clinical isolate of T. vaginalis was used for study of the protein expression in this species. Two-dimensional gel electrophoresis (2-DE) and MALDI-TOF/TOF mass spectrometry (MS) were employed to create a reference map of soluble proteins in the pH range 4-7. A set of 116 proteins belonging to functional classes expressed in high and low abundance was identified by peptide mass fingerprinting and tandem MS. These identifications corresponded to 67 different proteins, suggesting that post-translational modifications are common phenomena in T. vaginalis. Identified proteins were classified into 16 groups according to biological processes. Among detected proteins we identified the major enzymes involved in both cytosolic and hydrogenosomal metabolic pathways, as well as putative protein targets for new drug design. In addition, this analysis allows validation of previous gene predictions confirming the expression of 15 hypothetical proteins. Finally, the findings here reported represent the first reference proteome map of T. vaginalis and the first steps towards the description of a comprehensive proteome map of this parasite.