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  • In summary this is the first report describing the

    2019-12-02

    In summary, this is the first report describing the enzymatic characteristics, binding activity and localization of T. solium enolase. Here we demonstrate that Tseno gene possesses classical features of enolase family with highly conserved active sites, Mg2+ binding and plasminogen-binding motifs. The Tseno enzyme exhibits well glycolytic function with 60.72 ± 0.84 U/mg of the reaction activity in the forward conversion of 2-PGA to PEP. Its activity was significantly enhanced by the addition of low concentration of Mg2+. Notably, the His-Tseno-plasminogen interaction has been identified, which is inhabited by ε-ACA. The native Tseno is localized on the tegument and eggs, and it was upregulated in the adult stage of T. solium. These findings reveal that Tseno executes the innate glycolytic function to supply DMH-1 for worm growth, eggs production and even invasion of T. solium.
    Conclusions Our study has preliminarily characterized the enzymatic features, plasminogen binding activity, tissue localization and transcriptional levels of Tseno. The results suggested that Tseno could play an important role in the worm growth, egg production, and even invasion of T. solium.
    Ethics approval
    Competing interests
    Acknowledgments This work was supported by grants from the National Key Research and Development Program of China (No. 2017YFD0501303) and the National Natural Science Foundation of China (No. 31772726).
    Introduction Trichomonosis is the most-common non-viral sexually transmitted infection caused by the parasitic protozoan Trichomonas vaginalis, with >300 million cases annually worldwide [1]. A distinctive characteristic of T. vaginalis is that its genome harbors multiple paralogous copies for a wide majority of genes [2,3]. It is thought, that this genetic multiplicity provides to the parasite the ability to respond to drastic environmental changes (e.g., temperature, microflora, pH, iron concentration, polyamines, zinc, host immune responses, and other unknown factors), by modulating the expression of multiple genes [2,4]. Particularly, since T. vaginalis relies on fermentative carbohydrate catabolism, several copies of genes encoding for glycolytic enzymes have been retained during the evolution of this parasite. That is the case of enolase, whose canonical function is the reversible dehydration of 2-phosphoglycerate to phosphoenolpyruvate, the ninth and penultimate step of glycolysis [5]. In addition, this enzyme has been described as a moonlighting protein, in T. vaginalis serving as a plasminogen receptor on the cell surface of the parasite [6]. Due to this novel function and location within T. vaginalis, enolase has been stablished as a new surface-associated virulence factor. The overall scaffold of this enzyme is very similar among several organisms [7], but its sequence is moderately conserved [8] and it is possible to find important differences between pathogenic and host enzymes. In consequence, enolase has been proposed as an attractive target for drug discovery and vaccine development in several pathogens like Toxoplasma gondii, Leptospira spp., and Trypanosomatid parasites, among others [[9], [10], [11], [12]]. Furthermore, novel strategies to treat physiopathologies like cancer and type 2 diabetes mellitus (and comorbidities) have targeted the moonlighting (non-glycolytic) functions of enolase [13,14]. In TrichDB database (www.trichdb.org) there are 9 gene-sequences explicitly annotated as enolase [15,16], but they have not been fully characterized. Here we used a combination of bioinformatics, molecular and proteomic approaches to characterize the sequence and expression of enolase genes in Trichomonas vaginalis genome. This information contributes in identifying novel drug and vaccine strategies to combat trichomonosis.
    Materials and methods
    Results
    3.5 mRNA levels A hallmark on the metabolism of Trichomonas vaginalis, is the dependence of the expression of several genes on the iron concentration within the culture-media. We analyzed the mRNA levels of enolase genes and their dependence of iron abundance in the culture media (Fig. 4) in CNCD-147 isolate. The gene corresponding to TVAG_487600, was not amplified, even though a wide range of experimental conditions were assayed. Therefore, this description comprehends the other seven enolase genes from T. vaginalis. Fold changes in mRNA levels (mean ± SD) are expressed relative to enolase gene TVAG_464170, under normal iron conditions; since the product of this gene has the highest number of ESTs reports (Table S1).