Biosynthesis and uptake of thiamine (vitamin B1) in bloodstream form Trypanosoma brucei brucei and interference of the vitamin with melarsen oxide activity

How much (ATP) does it cost to build a trypanosome? A theoretical study on the quantity of ATP needed to maintain and duplicate a bloodstream-form Trypanosoma brucei cell

ATP hydrolysis is required for the synthesis, transport and polymerization of monomers for macromolecules as well as for the assembly of the latter into cellular structures. Other cellular processes not directly related to synthesis of biomass, such as maintenance of membrane potential and cellular shape, also require ATP. The unicellular flagellated parasite Trypanosoma brucei has a complex digenetic life cycle. The primary energy source for this parasite in its bloodstream form (BSF) is glucose, which is abundant in the host's bloodstream. Here, we made a detailed estimation of the energy budget during the BSF cell cycle. As glycolysis is the source of most produced ATP, we calculated that a single parasite produces 6.0 x 1011 molecules of ATP/cell cycle. Total biomass production (which involves biomass maintenance and duplication) accounts for ~63% of the total energy budget, while the total biomass duplication accounts for the remaining ~37% of the ATP consumption, with in both cases translation being the most expensive process. These values allowed us to estimate a theoretical YATP of 10.1 (g biomass)/mole ATP and a theoretical [Formula: see text] of 28.6 (g biomass)/mole ATP. Flagellar motility, variant surface glycoprotein recycling, transport and maintenance of transmembrane potential account for less than 30% of the consumed ATP. Finally, there is still ~5.5% available in the budget that is being used for other cellular processes of as yet unknown cost. These data put a new perspective on the assumptions about the relative energetic weight of the processes a BSF trypanosome undergoes during its cell cycle.

Fluorometric Detection of Thiamine Based on Hemoglobin-Cu3(PO4)2 Nanoflowers (NFs) with Peroxidase Mimetic Activity

Component analysis plays an important role in food production, pharmaceutics and agriculture. Nanozymes have attracted wide attention in analytical applications for their enzyme-like properties. In this work, a fluorometric method is described for the determination of thiamine (TH) (vitamin B1) based on hemoglobin-Cu3(PO4)2 nanoflowers (Hb-Cu3(PO4)2 NFs) with peroxidase-like properties. The Hb-Cu3(PO4)2 NFs catalyzed the decomposition of H2O2 into ·OH radicals in an alkaline solution that could efficiently react with nonfluorescent thiamine to fluoresce thiochrome. The fluorescence of thiochrome was further enhanced with a nonionic surfactant, Tween 80. Under optimal reaction conditions, the linear range for thiamine was from 5 × 10-8 to 5 × 10-5 mol/L. The correlation coefficient for the calibration curve and the limit of detection (LOD) were 0.9972 and 4.8 × 10-8 mol/L, respectively. The other vitamins did not bring about any obvious changes in fluorescence. The developed method based on hybrid nanoflowers is specific, pragmatically simple and sensitive, and has potential for application in thiamine detection.

Purine and pyrimidine transporters of pathogenic protozoa - conduits for therapeutic agents

Purines and pyrimidines are essential nutrients for any cell. Most organisms are able to synthesize their own purines and pyrimidines, but this ability was lost in protozoans that adapted to parasitism, leading to a great diversification in transporter activities in these organisms, especially for the acquisition of amino acids and nucleosides from their hosts throughout their life cycles. Many of these transporters have been shown to have sufficiently different substrate affinities from mammalian transporters, making them good carriers for therapeutic agents. In this review, we summarize the knowledge obtained on purine and pyrimidine activities identified in protozoan parasites to date and discuss their importance for the survival of these parasites and as drug carriers, as well as the perspectives of developments in the field.

Gene expression profiling of Trypanosoma cruzi in the presence of heme points to glycosomal metabolic adaptation of epimastigotes inside the vector

Chagas disease, also known as American trypanosomiasis, is a potentially life-threatening illness caused by the protozoan parasite, Trypanosoma cruzi, and is transmitted by triatomine insects during its blood meal. Proliferative epimastigotes forms thrive inside the insects in the presence of heme (iron protoporphyrin IX), an abundant product of blood digestion, however little is known about the metabolic outcome of this signaling molecule in the parasite. Trypanosomatids exhibit unusual gene transcription employing a polycistronic transcription mechanism through trans-splicing that regulates its life cycle. Using the Deep Seq transcriptome sequencing we characterized the heme induced transcriptome of epimastigotes and determined that most of the upregulated genes were related to glucose metabolism inside the glycosomes. These results were supported by the upregulation of glycosomal isoforms of PEPCK and fumarate reductase of heme-treated parasites, implying that the fermentation process was favored. Moreover, the downregulation of mitochondrial gene enzymes in the presence of heme also supported the hypothesis that heme shifts the parasite glycosomal glucose metabolism towards aerobic fermentation. These results are examples of the environmental metabolic plasticity inside the vector supporting ATP production, promoting epimastigotes proliferation and survival.

In silico ionomics segregates parasitic from free-living eukaryotes

Ion transporters are fundamental to life. Due to their ancient origin and conservation in sequence, ion transporters are also particularly well suited for comparative genomics of distantly related species. Here, we perform genome-wide ion transporter profiling as a basis for comparative genomics of eukaryotes. From a given predicted proteome, we identify all bona fide ion channels, ion porters, and ion pumps. Concentrating on unicellular eukaryotes (n = 37), we demonstrate that clustering of species according to their repertoire of ion transporters segregates obligate endoparasites (n = 23) on the one hand, from free-living species and facultative parasites (n = 14) on the other hand. This surprising finding indicates strong convergent evolution of the parasites regarding the acquisition and homeostasis of inorganic ions. Random forest classification identifies transporters of ammonia, plus transporters of iron and other transition metals, as the most informative for distinguishing the obligate parasites. Thus, in silico ionomics further underscores the importance of iron in infection biology and suggests access to host sources of nitrogen and transition metals to be selective forces in the evolution of parasitism. This finding is in agreement with the phenomenon of iron withholding as a primordial antimicrobial strategy of infected mammals.

Metabolomic analysis of trypanosomatid protozoa

Metabolomics aims to measure all low molecular weight chemicals within a given system in a manner analogous to transcriptomics, proteomics and genomics. In this review we highlight metabolomics approaches that are currently being applied to the kinetoplastid parasites, Trypanosoma brucei and Leishmania spp. The use of untargeted metabolomics approaches, made possible through advances in mass spectrometry and informatics, and stable isotope labelling has increased our understanding of the metabolism in these organisms beyond the views established using classical biochemical approaches. Set within the context of metabolic networks, predicted using genome-wide reconstructions of metabolism, new hypotheses on how to target aspects of metabolism to design new drugs against these protozoa are emerging.

How can your parasites become your allies?

Although parasitic infection is usually detrimental, it can be beneficial to the host in some situations. Parasites could help their host by providing a new function or modifying one of the host's life-history traits. We argue that the evolution towards a lasting mutualistic relationship would be more likely when parasites endow hosts with new abilities rather than alter a trait because hosts are less likely to evolve a new capability on their own than adjust their life history by microevolutionary steps. Furthermore, we underline how evolved dependence--the host's loss of ability to live alone owing to a long history of evolution in the presence of its parasites--has shaped contemporary mutualistic relationships.