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

Abstract

dTriosephosphate isomerase of Trichomonas vaginalis (TvTIM) is a 27-kDa cytoplasmic protein encoded by two genes, tvtim1 and tvtim2, that participates in glucose metabolism. TvTIM is also localized to the parasite surface. Thus, the goal of this study was to identify the novel functions of the surface-associated TvTIM in T. vaginalis and to assess the effect of glucose as an environmental factor that regulates its expression and localization. Reverse transcription-PCR (RT-PCR) showed that the tvtim genes were differentially expressed in response to glucose concentration. tvtim1 was overexpressed under glucose-restricted (GR) conditions, whereas tvtim2 was overexpressed under glucose-rich, or high-glucose (HG), conditions. Western blot and indirect immunofluorescence assays also showed that glucose positively affected the amount and surface localization of TvTIM in T. vaginalis. Affinity ligand assays demonstrated that the recombinant TvTIM1 and TvTIM2 proteins bound to laminin (Lm) and fibronectin (Fn) but not to plasminogen. Moreover, higher levels of adherence to Lm and Fn were detected in parasites grown under HG conditions than in those grown under GR conditions. Furthermore, pretreatment of trichomonads with an anti-TvTIMr polyclonal antibody or pretreatment of Lm-or Fn-coated wells with both recombinant proteins (TvTIM1r and TvTIM2r) specifically reduced the binding of live parasites to Lm and Fn in a concentration-dependent manner. Moreover, T. vaginalis was exposed to different glucose concentrations during vaginal infection of women with trichomoniasis. Our data indicate that TvTIM is a surface-associated protein under HG conditions that mediates specific binding to Lm and Fn as a novel virulence factor of T. vaginalis.T richomonas vaginalis is a protozoan parasite responsible for human trichomoniasis, the most common nonviral sexually transmitted infection, which affects over 276 million people annually worldwide (1). Infection with this organism is associated with severe health complications, such as vaginitis, preterm delivery, urethritis, prostatitis, infertility, and increases in the risks of prostate and cervical cancer. It has also been implicated in facilitating the infection and transmission of human immunodeficiency virus (HIV) (2-4).To establish an infection in the vagina, T. vaginalis must cross the vaginal mucus, adhere to the vaginal and cervical epithelia, and multiply in and colonize the urogenital tract (2, 5). The vagina is one of the most complex mucosal microenvironments and is constantly changing during the menstrual cycle. However, in vitro studies have shown that T. vaginalis adapts and responds to these changes, modulating the expression of multiple genes, including those encoding virulence factors, to maintain a chronic infection (6).Energy generation is vital to the maintenance of chronic infection and depends on the availability of nutrients, such as iron and a carbon source. For T. vaginalis, glucose is the major energy source under both anaerobic and aerobic conditions. With...

Glucose-restriction increasesTrichomonas vaginaliscellular damage towards HeLa cells and proteolytic activity of cysteine proteinases (CPs), such as TvCP2

“…We recently reported that T. vaginalis is exposed to different glucose levels (0.3–36.65 m m ) during vaginal infection of women with trichomoniasis. We also reported that glucose promotes trichomonad growth and increases the adherence levels of parasites to laminin and fibronectin (Miranda-Ozuna et al ., 2016). Trichomonas vaginalis also activates survival mechanism, such as metabolic reprogramming, enhancing antioxidant ability and autophagy, as a response to nutritional stress by glucose restriction (Huang et al ., 2014, 2017).…”

Analysis of the Trichuris suis excretory/secretory proteins as a function of life cycle stage and their immunomodulatory properties

“…It remains unclear, however, how this enzyme alters the phenotype of host immune cells. Evidence for a moonlighting function of TPI has been reported for Trichomonas vaginalis 78 and the fungal pathogen Paracoccidioides brasiliensis 79 , where surface-associated TPI interacts with extracellular matrix components such as laminin and fibronectin to facilitate adhesion and invasion. Although this alternate function for TPI does not address molecular mechanisms implicated in immunomodulation, it does suggest that uncharacterized and perhaps unexpected roles for such enzymes in the infection process.…”

Structural insights from a novel invertebrate triosephosphate isomerase from Litopenaeus vannamei

“…Also, LvTIM shows an uncommon Ala in the position 236, which could explain the lower thermal stability compared with other mesophilic species, but further studies are recommended. Functional studies indicate that TIMs are moonlighting proteins involved in cell-adhesion [58, 59] and that these new functions imply dimer-monomer equilibrium [58]. We propose that the low stability of LvTIM may be part of a regulatory mechanism that regulates glycolysis and that this mechanism may also involve dimer-monomer transitions.…”