Membrane Proteins in Parasitic Protozoa

A special issue of Genes (ISSN 2073-4425). This special issue belongs to the section "Microbial Genetics and Genomics".

Deadline for manuscript submissions: closed (31 May 2018) | Viewed by 70955

Special Issue Editors

Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Interests: metabolism; parasitic diseases; molecular parasitology; protozoology; evolutionary parasitology; pathogenesis; NTD drug development; Entamoeba vesicular traffic
Special Issues, Collections and Topics in MDPI journals
1. Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan‪ ‬
2. Visiting Researcher, ‬‪Department of Biomedical Chemistry, ‬Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo ‪113-0033‬, Japan
Interests: mitosome; mitochondrion related organelles; membrane proteins; beta barrel proteins; Entamoeba histolytica

Special Issue Information

Dear Colleagues,

The cell and its organelles are bound by membrane barriers, which are lined with proteins that perform various functions. In parasites, divergent mechanisms exist as a means to evade the host immune system, with some involving membrane proteins that play roles related to metabolism, transport, signaling, and pathogenesis among others. Intracellular membrane proteins, especially in parasite-specific organelles, are also known to play various essential roles in protein and metabolite transport, lipid exchange, organelle dynamics, organelle–organelle crosstalk, and biogenesis.

The significance of the diverse roles of membrane proteins have attracted extensive researches on this field, as the discovery and further understanding of membrane in human parasites, and their roles will immensely contribute to the fields of parasite cell biology and evolution in general, and could support the development of new parasite-specific drugs. In this Special Issue of Genes, the focus is on studies related to parasite membrane proteins, from the mechanisms of genetic acquisition, phylogeny and evolution, to structural and functional elucidations.

We cordially invite researchers working actively in these fields to submit their original research or review manuscripts to this research topic of membrane proteins in parasitic organisms.

Prof. Tomoyoshi Nozaki
Dr. Herbert J. Santos
Guest Editors

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Keywords

  • parasite
  • membrane proteins
  • host-parasite interaction
  • transport
  • biogenesis
  • organelles
  • pathogenesis
  • evolution

Published Papers (13 papers)

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Research

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11 pages, 2129 KiB  
Article
Identification of Plasmodium falciparum Mitochondrial Malate: Quinone Oxidoreductase Inhibitors from the Pathogen Box
by Xinying Wang, Yukiko Miyazaki, Daniel Ken Inaoka, Endah Dwi Hartuti, Yoh-Ichi Watanabe, Tomoo Shiba, Shigeharu Harada, Hiroyuki Saimoto, Jeremy Nicholas Burrows, Francisco Javier Gamo Benito, Tomoyoshi Nozaki and Kiyoshi Kita
Genes 2019, 10(6), 471; https://doi.org/10.3390/genes10060471 - 21 Jun 2019
Cited by 26 | Viewed by 4899
Abstract
Malaria is one of the three major global health threats. Drug development for malaria, especially for its most dangerous form caused by Plasmodium falciparum, remains an urgent task due to the emerging drug-resistant parasites. Exploration of novel antimalarial drug targets identified a [...] Read more.
Malaria is one of the three major global health threats. Drug development for malaria, especially for its most dangerous form caused by Plasmodium falciparum, remains an urgent task due to the emerging drug-resistant parasites. Exploration of novel antimalarial drug targets identified a trifunctional enzyme, malate quinone oxidoreductase (MQO), located in the mitochondrial inner membrane of P. falciparum (PfMQO). PfMQO is involved in the pathways of mitochondrial electron transport chain, tricarboxylic acid cycle, and fumarate cycle. Recent studies have shown that MQO is essential for P. falciparum survival in asexual stage and for the development of experiment cerebral malaria in the murine parasite P. berghei, providing genetic validation of MQO as a drug target. However, chemical validation of MQO, as a target, remains unexplored. In this study, we used active recombinant protein rPfMQO overexpressed in bacterial membrane fractions to screen a total of 400 compounds from the Pathogen Box, released by Medicines for Malaria Venture. The screening identified seven hit compounds targeting rPfMQO with an IC50 of under 5 μM. We tested the activity of hit compounds against the growth of 3D7 wildtype strain of P. falciparum, among which four compounds showed an IC50 from low to sub-micromolar concentrations, suggesting that PfMQO is indeed a potential antimalarial drug target. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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14 pages, 2954 KiB  
Article
An Entamoeba-Specific Mitosomal Membrane Protein with Potential Association to the Golgi Apparatus
by Herbert J. Santos, Yuki Hanadate, Kenichiro Imai and Tomoyoshi Nozaki
Genes 2019, 10(5), 367; https://doi.org/10.3390/genes10050367 - 13 May 2019
Cited by 6 | Viewed by 2832
Abstract
The aerobic mitochondrion had undergone evolutionary diversification, most notable among lineages of anaerobic protists. Entamoeba is one of the genera of parasitic protozoans that lack canonical mitochondria, and instead possess mitochondrion-related organelles (MROs), specifically mitosomes. Entamoeba mitosomes exhibit functional reduction and divergence, most [...] Read more.
The aerobic mitochondrion had undergone evolutionary diversification, most notable among lineages of anaerobic protists. Entamoeba is one of the genera of parasitic protozoans that lack canonical mitochondria, and instead possess mitochondrion-related organelles (MROs), specifically mitosomes. Entamoeba mitosomes exhibit functional reduction and divergence, most exemplified by the organelle’s inability to produce ATP and synthesize iron-sulfur cluster. Instead, this organelle is capable of sulfate activation, which has been linked to amoebic stage conversion. In order to understand other unique features and components of this MRO, we utilized an in silico prediction tool to screen transmembrane domain containing proteins in the mitosome proteome. Here, we characterize a novel lineage-specific mitosomal membrane protein, named Entamoeba transmembrane mitosomal protein of 30 kDa (ETMP30; EHI_172170), predicted to contain five transmembrane domains. Immunofluorescence analysis demonstrated colocalization of hemagglutinin (HA)-tagged ETMP30 with the mitosomal marker, adenosine-5’-phosphosulfate kinase. Mitosomal membrane localization was indicated by immunoelectron microscopy analysis, which was supported by carbonate fractionation assay. Transcriptional gene silencing successfully repressed RNA expression by 60%, and led to a defect in growth and partial elongation of mitosomes. Immunoprecipitation of ETMP30 from ETMP30-HA-expressing transformant using anti-HA antibody pulled down one interacting protein of 126 kDa. Protein sequencing by mass spectrometry revealed this protein as a cation-transporting P-type ATPase, previously reported to localize to vacuolar compartments/Golgi-like structures, hinting at a possible mitosome-vacuole/Golgi contact site. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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15 pages, 939 KiB  
Article
Novel Characteristics of Mitochondrial Electron Transport Chain from Eimeria tenella
by Makoto Matsubayashi, Daniel Ken Inaoka, Keisuke Komatsuya, Takeshi Hatta, Fumiya Kawahara, Kimitoshi Sakamoto, Kenji Hikosaka, Junya Yamagishi, Kazumi Sasai, Tomoo Shiba, Shigeharu Harada, Naotoshi Tsuji and Kiyoshi Kita
Genes 2019, 10(1), 29; https://doi.org/10.3390/genes10010029 - 08 Jan 2019
Cited by 13 | Viewed by 5206
Abstract
Eimeria tenella is an intracellular apicomplexan parasite, which infects cecal epithelial cells from chickens and causes hemorrhagic diarrhea and eventual death. We have previously reported the comparative RNA sequence analysis of the E. tenella sporozoite stage between virulent and precocious strains and showed [...] Read more.
Eimeria tenella is an intracellular apicomplexan parasite, which infects cecal epithelial cells from chickens and causes hemorrhagic diarrhea and eventual death. We have previously reported the comparative RNA sequence analysis of the E. tenella sporozoite stage between virulent and precocious strains and showed that the expression of several genes involved in mitochondrial electron transport chain (ETC), such as type II NADH dehydrogenase (NDH-2), complex II (succinate:quinone oxidoreductase), malate:quinone oxidoreductase (MQO), and glycerol-3-phosphate dehydrogenase (G3PDH), were upregulated in virulent strain. To study E. tenella mitochondrial ETC in detail, we developed a reproducible method for preparation of mitochondria-rich fraction from sporozoites, which maintained high specific activities of dehydrogenases, such as NDH-2 followed by G3PDH, MQO, complex II, and dihydroorotate dehydrogenase (DHODH). Of particular importance, we showed that E. tenella sporozoite mitochondria possess an intrinsic ability to perform fumarate respiration (via complex II) in addition to the classical oxygen respiration (via complexes III and IV). Further analysis by high-resolution clear native electrophoresis, activity staining, and nano-liquid chromatography tandem-mass spectrometry (nano-LC-MS/MS) provided evidence of a mitochondrial complex II-III-IV supercomplex. Our analysis suggests that complex II from E. tenella has biochemical features distinct to known orthologues and is a potential target for the development of new anticoccidian drugs. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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17 pages, 941 KiB  
Article
Bioinformatics Analysis and Functional Prediction of Transmembrane Proteins in Entamoeba histolytica
by Tamanna Anwar and Gourinath Samudrala
Genes 2018, 9(10), 499; https://doi.org/10.3390/genes9100499 - 16 Oct 2018
Cited by 5 | Viewed by 5985
Abstract
Entamoeba histolytica is an invasive, pathogenic parasite causing amoebiasis. Given that proteins involved in transmembrane (TM) transport are crucial for the adherence, invasion, and nutrition of the parasite, we conducted a genome-wide bioinformatics analysis of encoding proteins to functionally classify and characterize all [...] Read more.
Entamoeba histolytica is an invasive, pathogenic parasite causing amoebiasis. Given that proteins involved in transmembrane (TM) transport are crucial for the adherence, invasion, and nutrition of the parasite, we conducted a genome-wide bioinformatics analysis of encoding proteins to functionally classify and characterize all the TM proteins in E. histolytica. In the present study, 692 TM proteins have been identified, of which 546 are TM transporters. For the first time, we report a set of 141 uncharacterized proteins predicted as TM transporters. The percentage of TM proteins was found to be lower in comparison to the free-living eukaryotes, due to the extracellular nature and functional diversification of the TM proteins. The number of multi-pass proteins is larger than the single-pass proteins; though both have their own significance in parasitism, multi-pass proteins are more extensively required as these are involved in acquiring nutrition and for ion transport, while single-pass proteins are only required at the time of inciting infection. Overall, this intestinal parasite implements multiple mechanisms for establishing infection, obtaining nutrition, and adapting itself to the new host environment. A classification of the repertoire of TM transporters in the present study augments several hints on potential methods of targeting the parasite for therapeutic benefits. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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11 pages, 3200 KiB  
Article
Functional Analyses of a Putative, Membrane-Bound, Peroxisomal Protein Import Mechanism from the Apicomplexan Protozoan Toxoplasma gondii
by Alison J. Mbekeani, Will A. Stanley, Vishal C. Kalel, Noa Dahan, Einat Zalckvar, Lilach Sheiner, Wolfgang Schliebs, Ralf Erdmann, Ehmke Pohl and Paul W. Denny
Genes 2018, 9(9), 434; https://doi.org/10.3390/genes9090434 - 29 Aug 2018
Cited by 1 | Viewed by 6378
Abstract
Peroxisomes are central to eukaryotic metabolism, including the oxidation of fatty acids—which subsequently provide an important source of metabolic energy—and in the biosynthesis of cholesterol and plasmalogens. However, the presence and nature of peroxisomes in the parasitic apicomplexan protozoa remains controversial. A survey [...] Read more.
Peroxisomes are central to eukaryotic metabolism, including the oxidation of fatty acids—which subsequently provide an important source of metabolic energy—and in the biosynthesis of cholesterol and plasmalogens. However, the presence and nature of peroxisomes in the parasitic apicomplexan protozoa remains controversial. A survey of the available genomes revealed that genes encoding peroxisome biogenesis factors, so-called peroxins (Pex), are only present in a subset of these parasites, the coccidia. The basic principle of peroxisomal protein import is evolutionarily conserved, proteins harbouring a peroxisomal-targeting signal 1 (PTS1) interact in the cytosol with the shuttling receptor Pex5 and are then imported into the peroxisome via the membrane-bound protein complex formed by Pex13 and Pex14. Surprisingly, whilst Pex5 is clearly identifiable, Pex13 and, perhaps, Pex14 are apparently absent from the coccidian genomes. To investigate the functionality of the PTS1 import mechanism in these parasites, expression of Pex5 from the model coccidian Toxoplasma gondii was shown to rescue the import defect of Pex5-deleted Saccharomyces cerevisiae. In support of these data, green fluorescent protein (GFP) bearing the enhanced (e)PTS1 known to efficiently localise to peroxisomes in yeast, localised to peroxisome-like bodies when expressed in Toxoplasma. Furthermore, the PTS1-binding domain of Pex5 and a PTS1 ligand from the putatively peroxisome-localised Toxoplasma sterol carrier protein (SCP2) were shown to interact in vitro. Taken together, these data demonstrate that the Pex5–PTS1 interaction is functional in the coccidia and indicate that a nonconventional peroxisomal import mechanism may operate in the absence of Pex13 and Pex14. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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29 pages, 3918 KiB  
Article
Proteome-Wide Analysis of Trypanosoma cruzi Exponential and Stationary Growth Phases Reveals a Subcellular Compartment-Specific Regulation
by Carla Cristi Avila, Simon Ngao Mule, Livia Rosa-Fernandes, Rosa Viner, María Julia Barisón, André Guillherme Costa-Martins, Gilberto Santos De Oliveira, Marta Maria Geraldes Teixeira, Claudio Romero Farias Marinho, Ariel Mariano Silber and Giuseppe Palmisano
Genes 2018, 9(8), 413; https://doi.org/10.3390/genes9080413 - 15 Aug 2018
Cited by 23 | Viewed by 5179
Abstract
Trypanosoma cruzi, the etiologic agent of Chagas disease, cycles through different life stages characterized by defined molecular traits associated with the proliferative or differentiation state. In particular, T. cruzi epimastigotes are the replicative forms that colonize the intestine of the Triatomine insect [...] Read more.
Trypanosoma cruzi, the etiologic agent of Chagas disease, cycles through different life stages characterized by defined molecular traits associated with the proliferative or differentiation state. In particular, T. cruzi epimastigotes are the replicative forms that colonize the intestine of the Triatomine insect vector before entering the stationary phase that is crucial for differentiation into metacyclic trypomastigotes, which are the infective forms of mammalian hosts. The transition from proliferative exponential phase to quiescent stationary phase represents an important step that recapitulates the early molecular events of metacyclogenesis, opening new possibilities for understanding this process. In this study, we report a quantitative shotgun proteomic analysis of the T. cruzi epimastigote in the exponential and stationary growth phases. More than 3000 proteins were detected and quantified, highlighting the regulation of proteins involved in different subcellular compartments. Ribosomal proteins were upregulated in the exponential phase, supporting the higher replication rate of this growth phase. Autophagy-related proteins were upregulated in the stationary growth phase, indicating the onset of the metacyclogenesis process. Moreover, this study reports the regulation of N-terminally acetylated proteins during growth phase transitioning, adding a new layer of regulation to this process. Taken together, this study reports a proteome-wide rewiring during T. cruzi transit from the replicative exponential phase to the stationary growth phase, which is the preparatory phase for differentiation. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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Review

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32 pages, 2548 KiB  
Review
Host Invasion by Pathogenic Amoebae: Epithelial Disruption by Parasite Proteins
by Abigail Betanzos, Cecilia Bañuelos and Esther Orozco
Genes 2019, 10(8), 618; https://doi.org/10.3390/genes10080618 - 14 Aug 2019
Cited by 40 | Viewed by 7702
Abstract
The epithelium represents the first and most extensive line of defence against pathogens, toxins and pollutant agents in humans. In general, pathogens have developed strategies to overcome this barrier and use it as an entrance to the organism. Entamoeba histolytica, Naegleria fowleri [...] Read more.
The epithelium represents the first and most extensive line of defence against pathogens, toxins and pollutant agents in humans. In general, pathogens have developed strategies to overcome this barrier and use it as an entrance to the organism. Entamoeba histolytica, Naegleria fowleri and Acanthamoeba spp. are amoebae mainly responsible for intestinal dysentery, meningoencephalitis and keratitis, respectively. These amoebae cause significant morbidity and mortality rates. Thus, the identification, characterization and validation of molecules participating in host-parasite interactions can provide attractive targets to timely intervene disease progress. In this work, we present a compendium of the parasite adhesins, lectins, proteases, hydrolases, kinases, and others, that participate in key pathogenic events. Special focus is made for the analysis of assorted molecules and mechanisms involved in the interaction of the parasites with epithelial surface receptors, changes in epithelial junctional markers, implications on the barrier function, among others. This review allows the assessment of initial host-pathogen interaction, to correlate it to the potential of parasite invasion. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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27 pages, 1076 KiB  
Review
ATPe Dynamics in Protozoan Parasites. Adapt or Perish
by Natalia Lauri, Zaher Bazzi, Cora L. Alvarez, María F. Leal Denis, Julieta Schachter, Vanesa Herlax, Mariano A. Ostuni and Pablo J. Schwarzbaum
Genes 2019, 10(1), 16; https://doi.org/10.3390/genes10010016 - 27 Dec 2018
Cited by 3 | Viewed by 5321
Abstract
In most animals, transient increases of extracellular ATP (ATPe) are used for physiological signaling or as a danger signal in pathological conditions. ATPe dynamics are controlled by ATP release from viable cells and cell lysis, ATPe degradation and interconversion by ecto-nucleotidases, and interaction [...] Read more.
In most animals, transient increases of extracellular ATP (ATPe) are used for physiological signaling or as a danger signal in pathological conditions. ATPe dynamics are controlled by ATP release from viable cells and cell lysis, ATPe degradation and interconversion by ecto-nucleotidases, and interaction of ATPe and byproducts with cell surface purinergic receptors and purine salvage mechanisms. Infection by protozoan parasites may alter at least one of the mechanisms controlling ATPe concentration. Protozoan parasites display their own set of proteins directly altering ATPe dynamics, or control the activity of host proteins. Parasite dependent activation of ATPe conduits of the host may promote infection and systemic responses that are beneficial or detrimental to the parasite. For instance, activation of organic solute permeability at the host membrane can support the elevated metabolism of the parasite. On the other hand ecto-nucleotidases of protozoan parasites, by promoting ATPe degradation and purine/pyrimidine salvage, may be involved in parasite growth, infectivity, and virulence. In this review, we will describe the complex dynamics of ATPe regulation in the context of protozoan parasite–host interactions. Particular focus will be given to features of parasite membrane proteins strongly controlling ATPe dynamics. This includes evolutionary, genetic and cellular mechanisms, as well as structural-functional relationships. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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19 pages, 1304 KiB  
Review
Protein Import into the Endosymbiotic Organelles of Apicomplexan Parasites
by Natalia Mallo, Justin Fellows, Carla Johnson and Lilach Sheiner
Genes 2018, 9(8), 412; https://doi.org/10.3390/genes9080412 - 14 Aug 2018
Cited by 13 | Viewed by 6763
Abstract
The organelles of endosymbiotic origin, plastids, and mitochondria, evolved through the serial acquisition of endosymbionts by a host cell. These events were accompanied by gene transfer from the symbionts to the host, resulting in most of the organellar proteins being encoded in the [...] Read more.
The organelles of endosymbiotic origin, plastids, and mitochondria, evolved through the serial acquisition of endosymbionts by a host cell. These events were accompanied by gene transfer from the symbionts to the host, resulting in most of the organellar proteins being encoded in the cell nuclear genome and trafficked into the organelle via a series of translocation complexes. Much of what is known about organelle protein translocation mechanisms is based on studies performed in common model organisms; e.g., yeast and humans or Arabidopsis. However, studies performed in divergent organisms are gradually accumulating. These studies provide insights into universally conserved traits, while discovering traits that are specific to organisms or clades. Apicomplexan parasites feature two organelles of endosymbiotic origin: a secondary plastid named the apicoplast and a mitochondrion. In the context of the diseases caused by apicomplexan parasites, the essential roles and divergent features of both organelles make them prime targets for drug discovery. This potential and the amenability of the apicomplexan Toxoplasma gondii to genetic manipulation motivated research about the mechanisms controlling both organelles’ biogenesis. Here we provide an overview of what is known about apicomplexan organelle protein import. We focus on work done mainly in T. gondii and provide a comparison to model organisms. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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13 pages, 658 KiB  
Review
Membrane-Associated Proteins in Giardia lamblia
by María C. Touz, Constanza Feliziani and Andrea S. Rópolo
Genes 2018, 9(8), 404; https://doi.org/10.3390/genes9080404 - 10 Aug 2018
Cited by 9 | Viewed by 5325
Abstract
The manner in which membrane-associated proteins interact with the membrane defines their subcellular fate and function. This interaction relies on the characteristics of the proteins, their journey after synthesis, and their interaction with other proteins or enzymes. Understanding these properties may help to [...] Read more.
The manner in which membrane-associated proteins interact with the membrane defines their subcellular fate and function. This interaction relies on the characteristics of the proteins, their journey after synthesis, and their interaction with other proteins or enzymes. Understanding these properties may help to define the function of a protein and also the role of an organelle. In the case of microorganisms like protozoa parasites, it may help to understand singular features that will eventually lead to the design of parasite-specific drugs. The protozoa parasite Giardia lamblia is an example of a widespread parasite that has been infecting humans and animals from ancestral times, adjusting itself to the changes of the environment inside and outside the host. Several membrane-associated proteins have been posted in the genome database GiardiaDB, although only a few of them have been characterized. This review discusses the data regarding membrane-associated proteins in relationship with lipids and specific organelles and their implication in the discovery of anti-giardial therapies. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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16 pages, 1610 KiB  
Review
Adaptation and Therapeutic Exploitation of the Plasma Membrane of African Trypanosomes
by Juan F. Quintana, Ricardo Canavate Del Pino, Kayo Yamada, Ning Zhang and Mark C. Field
Genes 2018, 9(7), 368; https://doi.org/10.3390/genes9070368 - 20 Jul 2018
Cited by 7 | Viewed by 5471
Abstract
African trypanosomes are highly divergent from their metazoan hosts, and as part of adaptation to a parasitic life style have developed a unique endomembrane system. The key virulence mechanism of many pathogens is successful immune evasion, to enable survival within a host, a [...] Read more.
African trypanosomes are highly divergent from their metazoan hosts, and as part of adaptation to a parasitic life style have developed a unique endomembrane system. The key virulence mechanism of many pathogens is successful immune evasion, to enable survival within a host, a feature that requires both genetic events and membrane transport mechanisms in African trypanosomes. Intracellular trafficking not only plays a role in immune evasion, but also in homeostasis of intracellular and extracellular compartments and interactions with the environment. Significantly, historical and recent work has unraveled some of the connections between these processes and highlighted how immune evasion mechanisms that are associated with adaptations to membrane trafficking may have, paradoxically, provided specific sensitivity to drugs. Here, we explore these advances in understanding the membrane composition of the trypanosome plasma membrane and organelles and provide a perspective for how transport could be exploited for therapeutic purposes. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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18 pages, 1144 KiB  
Review
Membrane Proteins in Trypanosomatids Involved in Ca2+ Homeostasis and Signaling
by Srinivasan Ramakrishnan and Roberto Docampo
Genes 2018, 9(6), 304; https://doi.org/10.3390/genes9060304 - 19 Jun 2018
Cited by 22 | Viewed by 4483
Abstract
Calcium ion (Ca2+) serves as a second messenger for a variety of cell functions in trypanosomes. Several proteins in the plasma membrane, acidocalcisomes, endoplasmic reticulum, and mitochondria are involved in its homeostasis and in cell signaling roles. The plasma membrane has [...] Read more.
Calcium ion (Ca2+) serves as a second messenger for a variety of cell functions in trypanosomes. Several proteins in the plasma membrane, acidocalcisomes, endoplasmic reticulum, and mitochondria are involved in its homeostasis and in cell signaling roles. The plasma membrane has a Ca2+ channel for its uptake and a plasma membrane-type Ca2+-ATPase (PMCA) for its efflux. A similar PMCA is also located in acidocalcisomes, acidic organelles that are the primary Ca2+ store and that possess an inositol 1,4,5-trisphosphate receptor (IP3R) for Ca2+ efflux. Their mitochondria possess a mitochondrial calcium uniporter complex (MCUC) for Ca2+ uptake and a Ca2+/H+ exchanger for Ca2+ release. The endoplasmic reticulum has a sarcoplasmic-endoplasmic reticulum-type Ca2+-ATPase (SERCA) for Ca2+ uptake but no Ca2+ release mechanism has been identified. Additionally, the trypanosomatid genomes contain other membrane proteins that could potentially bind calcium and await further characterization. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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Other

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6 pages, 1001 KiB  
Concept Paper
Membrane Surface Features of Blastocystis Subtypes
by John Anthony Yason and Kevin Shyong Wei Tan
Genes 2018, 9(8), 417; https://doi.org/10.3390/genes9080417 - 17 Aug 2018
Cited by 10 | Viewed by 3879
Abstract
Blastocystis is a common intestinal protistan parasite with global distribution. Blastocystis is a species complex composed of several isolates with biological and morphological differences. The surface coats of Blastocystis from three different isolates representing three subtypes were analyzed using scanning electron microscopy. This [...] Read more.
Blastocystis is a common intestinal protistan parasite with global distribution. Blastocystis is a species complex composed of several isolates with biological and morphological differences. The surface coats of Blastocystis from three different isolates representing three subtypes were analyzed using scanning electron microscopy. This structure contains carbohydrate components that are also present in surface glycoconjugates in other parasitic protozoa. Electron micrographs show variations in the surface coats from the three Blastocystis isolates. These differences could be associated with the differences in the pathogenic potential of Blastocystis subtypes. Apart from the surface coat, a plasma membrane-associated surface antigen has been described for Blastocystis ST7 and is associated with programmed cell death features of the parasite. Full article
(This article belongs to the Special Issue Membrane Proteins in Parasitic Protozoa)
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