scholarly journals Toxoplasma gondii serine hydrolases regulate parasite lipid mobilization during growth and replication within the host

2020 ◽  
Author(s):  
Ouma Onguka ◽  
Brett M. Babin ◽  
Markus Lakemeyer ◽  
Ian T. Foe ◽  
Neri Amara ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Biochemical Characterization ◽  
Lipid Synthesis ◽  
Protozoan Parasite ◽  
List Type ◽  
Serine Hydrolases ◽  
Metabolizing Enzymes ◽  
Thiol Esters ◽  
Intracellular Protozoan Parasite

SummaryThe intracellular protozoan parasite Toxoplasma gondii must scavenge cholesterol and other lipids from the host to facilitate intracellular growth and replication. Enzymes responsible for neutral lipid synthesis have been identified but there is no evidence for enzymes that catalyze lipolysis of cholesterol esters and esterified lipids. Here we characterize several T. gondii serine hydrolases with esterase and thioesterase activities that were previously thought to be depalmitoylating enzymes. We find they do not cleave palmitoyl thiol esters but rather hydrolyze short chain lipid esters. Deletion of one of the hydrolases results in alterations in levels of multiple lipids species. We also identify small molecule inhibitors of these hydrolases and show that treatment of parasites results in phenotypic defects reminiscent of parasites exposed to excess cholesterol or oleic acid. Together, these data characterize enzymes necessary for processing lipids critical for infection and highlight the potential for targeting parasite hydrolases for therapeutic applications.HighlightsBioinformatic and biochemical characterization of T. gondii serine hydrolases reveals substrate preference between enzymes with similar catalytic foldT. gondii serine hydrolases previously thought to be depalmitoylases are lipid metabolizing enzymesT. gondii lipid metabolism pathways utilize enzymes that are viable therapeutic targets

scholarly journals Identification and Characterization of an Escorter for Two Secretory Adhesins in Toxoplasma gondii

2001 ◽  
Vol 152 (3) ◽  
pp. 563-578 ◽  
Author(s):  
Matthias Reiss ◽  
Nicola Viebig ◽  
Susan Brecht ◽  
Marie-Noelle Fourmaux ◽  
Martine Soete ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Secretory Pathway ◽  
Protozoan Parasite ◽  
Host Cells ◽  
Plausible Mechanism ◽  
Identification And Characterization ◽  
Intracellular Protozoan Parasite ◽  
Cargo Molecule

The intracellular protozoan parasite Toxoplasma gondii shares with other members of the Apicomplexa a common set of apical structures involved in host cell invasion. Micronemes are apical secretory organelles releasing their contents upon contact with host cells. We have identified a transmembrane micronemal protein MIC6, which functions as an escorter for the accurate targeting of two soluble proteins MIC1 and MIC4 to the micronemes. Disruption of MIC1, MIC4, and MIC6 genes allowed us to precisely dissect their contribution in sorting processes. We have mapped domains on these proteins that determine complex formation and targeting to the organelle. MIC6 carries a sorting signal(s) in its cytoplasmic tail whereas its association with MIC1 involves a lumenal EGF-like domain. MIC4 binds directly to MIC1 and behaves as a passive cargo molecule. In contrast, MIC1 is linked to a quality control system and is absolutely required for the complex to leave the early compartments of the secretory pathway. MIC1 and MIC4 bind to host cells, and the existence of such a complex provides a plausible mechanism explaining how soluble adhesins act. We hypothesize that during invasion, MIC6 along with adhesins establishes a bridge between the host cell and the parasite.

scholarly journals N-glycan chitobiose core biosynthesis by Agl24 strengthens the hypothesis of an archaeal origin of the eukaryal N-glycosylation

2021 ◽  
Author(s):  
Benjamin H. Meyer ◽  
Ben A. Wagstaff ◽  
Panagiotis S. Adam ◽  
Sonja-Verena Albers ◽  
Helge C. Dorfmueller
Keyword(s):  
Posttranslational Modifications ◽  
Biochemical Characterization ◽  
Similar Process ◽  
List Type ◽  
Histidine Residue ◽  
Functional Importance ◽  
Domains Of Life ◽  
Distant Relation ◽  
Identification And Characterization

AbstractProtein N-glycosylation is the most common posttranslational modifications found in all three domains of life. The crenarchaeal N-glycosylation begins with the synthesis of a lipid-linked chitobiose core structure, identical to that in eukaryotes. Here, we report the identification of a thermostable archaeal beta-1,4-N-acetylglucosaminyltransferase, named archaeal glycosylation enzyme 24 (Agl24), responsible for the synthesis of the N-glycan chitobiose core. Biochemical characterization confirmed the function as an inverting β-D-GlcNAc-(1→4)-α-D-GlcNAc-diphosphodolichol glycosyltransferase. Substitution of a conserved histidine residue, found also in the eukaryotic and bacterial homologs, demonstrated its functional importance for Agl24. Furthermore, bioinformatics and structural modeling revealed strong similarities between Agl24 and both the eukaryotic Alg14/13 and a distant relation to the bacterial MurG, which catalyze the identical or a similar process, respectively. Our data, complemented by phylogenetic analysis of Alg13 and Alg14, revealed similar sequences in Asgardarchaeota, further supporting the hypothesis that the Alg13/14 homologs in eukaryotes have been acquired during eukaryogenesis.HighlightsFirst identification and characterization of a thermostable β-D-GlcNAc-(1→4)-α-D-GlcNAc-diphosphodolichol glycosyltransferase (GT family 28) in Archaea.A highly conserved histidine, within a GGH motif in Agl24, Alg14, and MurG, is essential for function of Agl24.Agl24-like homologs are broadly distributed among Archaea.The eukaryotic Alg13 and Alg14 are closely related to the Asgard homologs, suggesting their acquisition during eukaryogenesis.

Biochemical characterization of mitogen-activated protein (MAP) kinase activity in Toxoplasma gondii

2000 ◽  
Vol 86 (7) ◽  
pp. 588-598 ◽  
Author(s):  
Marie-Paule Roisin ◽  
Florence Robert-Gangneux ◽  
Claudine Creuzet ◽  
Jean Dupouy-Camet
Keyword(s):  
Toxoplasma Gondii ◽  
Map Kinase ◽  
Kinase Activity ◽  
Biochemical Characterization ◽  
Protein Map ◽  
Mitogen Activated Protein

Enrichment and biochemical characterization of Toxoplasma gondii tachyzoite plasmalemma

Parasitology ◽  
1997 ◽  
Vol 114 (5) ◽  
pp. 421-426 ◽  
Author(s):  
A. RABJEAU ◽  
F. FOUSSARD ◽  
G. MAURAS ◽  
J. F. DUBREMETZ
Keyword(s):  
Toxoplasma Gondii ◽  
Plasma Membranes ◽  
Biochemical Characterization ◽  
Surface Membrane ◽  
Surface Protein ◽  
Protozoan Parasite ◽  
Membrane Complex ◽  
Inner Membrane Complex ◽  
Partial Dissociation ◽  
Major Surface

The protozoan parasite Toxoplasma gondii possesses a triple surface membrane called the pellicle. This is made of an outer plasmalemma and an inner membrane complex lying under the plasmalemma. Using a high salt glycerol treatment followed by sonication, we have obtained a partial dissociation of the pellicle. A plasmalemma-enriched fraction was isolated on 0·7M sucrose. It was identified by immunodetection of the tachyzoite major surface antigens. Protein content, resolved by SDS–PAGE, revealed that the surface protein SAG1 is the major component of the plasmalemma. The plasmalemma fraction is made of small vesicles (20–100 nm) which possess a low density (1·085–1·090 g/cm3 in sucrose) contrasting with other eukaryotic plasma membranes (1·12–1·16 g/cm3).

scholarly journals The antifungal Aureobasidin A and an analogue are active against the protozoan parasite Toxoplasma gondii but do not inhibit sphingolipid biosynthesis

Parasitology ◽  
2017 ◽  
Vol 145 (2) ◽  
pp. 148-155 ◽  
Author(s):  
A. Q. I. ALQAISI ◽  
A. J. MBEKEANI ◽  
M. BASSAS LLORENS ◽  
A. P. ELHAMMER ◽  
P. W. DENNY
Keyword(s):  
Toxoplasma Gondii ◽  
Protozoan Parasite ◽  
Pathogenic Fungi ◽  
Significant Activity ◽  
Cyclic Depsipeptide ◽  
Aureobasidin A ◽  
Therapeutic Compounds ◽  
Sphingolipid Biosynthesis ◽  
Important Disease ◽  
Intracellular Protozoan Parasite

SUMMARYToxoplasma gondii is an obligate intracellular protozoan parasite of the phylum Apicomplexa, and toxoplasmosis is an important disease of both humans and economically important animals. With a limited array of drugs available there is a need to identify new therapeutic compounds. Aureobasidin A (AbA) is an antifungal that targets the essential inositol phosphorylceramide (IPC, sphingolipid) synthase in pathogenic fungi. This natural cyclic depsipeptide also inhibits Toxoplasma proliforation, with the protozoan IPC synthase orthologue proposed as the target. The data presented here show that neither AbA nor an analogue (Compound 20), target the protozoan IPC synthase orthologue or total parasite sphingolipid synthesis. However, further analyses confirm that AbA exhibits significant activity against the proliferative tachyzoite form of Toxoplasma, and Compound 20, whilst effective, has reduced efficacy. This difference was more evident on analyses of the direct effect of these compounds against isolated Toxoplasma, indicating that AbA is rapidly microbicidal. Importantly, the possibility of targeting the encysted, bradyzoite, form of the parasite with AbA and Compound 20 was demonstrated, indicating that this class of compounds may provide the basis for the first effective treatment for chronic toxoplasmosis.

scholarly journals MYST Family Histone Acetyltransferases in the Protozoan Parasite Toxoplasma gondii

2005 ◽  
Vol 4 (12) ◽  
pp. 2057-2065 ◽  
Author(s):  
Aaron T. Smith ◽  
Samantha D. Tucker-Samaras ◽  
Alan H. Fairlamb ◽  
William J. Sullivan
Keyword(s):  
Toxoplasma Gondii ◽  
Catalytic Domain ◽  
Regulation Of Gene Expression ◽  
Protozoan Parasite ◽  
Opportunistic Pathogen ◽  
Covalent Modification ◽  
Histone H4 ◽  
Genomic Locus

ABSTRACT The restructuring of chromatin precedes tightly regulated events such as DNA transcription, replication, and repair. One type of chromatin remodeling involves the covalent modification of nucleosomes by histone acetyltransferase (HAT) complexes. The observation that apicidin exerts antiprotozoal activity by targeting a histone deacetyltransferase has prompted our search for more components of the histone modifying machinery in parasitic protozoa. We have previously identified GNAT family HATs in the opportunistic pathogen Toxoplasma gondii and now describe the first MYST (named for members MOZ, Ybf2/Sas3, Sas2, and Tip60) family HATs in apicomplexa (TgMYST-A and -B). The TgMYST-A genomic locus is singular and generates a ∼3.5-kb transcript that can encode two proteins of 411 or 471 amino acids. TgMYST-B mRNA is ∼7.0 kb and encodes a second MYST homologue. In addition to the canonical MYST HAT catalytic domain, both TgMYST-A and -B possess an atypical C2HC zinc finger and a chromodomain. Recombinant TgMYST-A exhibits a predilection to acetylate histone H4 in vitro at lysines 5, 8, 12, and 16. Antibody generated to TgMYST-A reveals that both the long and short (predominant) versions are present in the nucleus and are also plentiful in the cytoplasm. Moreover, both TgMYST-A forms are far more abundant in rapidly replicating parasites (tachyzoites) than encysted parasites (bradyzoites). A bioinformatics survey of the Toxoplasma genome reveals numerous homologues known to operate in native MYST complexes. The characterization of TgMYST HATs represents another important step toward understanding the regulation of gene expression in pathogenic protozoa and provides evolutionary insight into how these processes operate in eukaryotic cells in general.

scholarly journals Investigation of Toxoplasma gondii Infection in Aborted Fetuses of Sheep Using PCR: A Study in North Khorasan Province, Iran

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Mitra Salehi ◽  
Hosein Nezami ◽  
Hamid Reza Niazkar
Keyword(s):  
Toxoplasma Gondii ◽  
Gestational Age ◽  
Protozoan Parasite ◽  
Abortion Rate ◽  
Obligate Intracellular ◽  
Significant Difference ◽  
Pcr Method ◽  
Toxoplasma Gondii Infection ◽  
Intracellular Protozoan Parasite

Toxoplasma gondii is a zoonotic obligate intracellular protozoan parasite that infects warm-blooded animals as well as humans worldwide. The purpose of this study was to delineate the prevalence of Toxoplasma infection in aborted fetuses of sheep in North Khorasan province, Iran. Three hundred and ninety-nine samples of the liver (133 samples), placenta (133 samples), and brain (133 samples) from 133 aborted fetuses of sheep were collected from 2015 to 2017. The ages of aborted fetuses were higher than 120 days’ gestational age in this study. According to the samples, sixteen out of 133 aborted fetuses of sheep were infected with T. gondii. Toxoplasma DNA was found in the placenta (68.75%) and liver (31.25%) samples of infected fetuses using the PCR method. The highest and lowest rates of Toxoplasma infection were observed during 2016 and 2017, respectively. Shirvan and Faruj provinces were recognized as the two most infected districts among others. There was a significant difference between the year and abortion rate in sheep due to infection by the Toxoplasma parasite (P<0.05). Furthermore, no significant difference between the prevalence of T. gondii infection and aborted fetuses was seen (P>0.05) in different areas. According to the present study, T. gondii infection can be one of the causes of fetus abortion of sheep in North Khorasan province, Iran.

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