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 Identification of PhIL1, a Novel Cytoskeletal Protein of the Toxoplasma gondii Pellicle, through Photosensitized Labeling with 5-[125I]Iodonaphthalene-1-Azide

2006 ◽  
Vol 5 (10) ◽  
pp. 1622-1634 ◽  
Author(s):  
Stacey D. Gilk ◽  
Yossef Raviv ◽  
Ke Hu ◽  
John M. Murray ◽  
Con J. M. Beckers ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Membrane Proteins ◽  
Transmembrane Domain ◽  
Protozoan Parasite ◽  
Integral Membrane Protein ◽  
Apicomplexan Parasites ◽  
Membrane Complex ◽  
Inner Membrane Complex ◽  
Complex Integral ◽  
Host Cell Recognition

ABSTRACT The pellicle of the protozoan parasite Toxoplasma gondii is a unique triple bilayer structure, consisting of the plasma membrane and two tightly apposed membranes of the underlying inner membrane complex. Integral membrane proteins of the pellicle are likely to play critical roles in host cell recognition, attachment, and invasion, but few such proteins have been identified. This is in large part because the parasite surface is dominated by a family of abundant and highly immunogenic glycosylphosphatidylinositol (GPI)-anchored proteins, which has made the identification of non-GPI-linked proteins difficult. To identify such proteins, we have developed a radiolabeling approach using the hydrophobic, photoactivatable compound 5-[125I]iodonaphthalene-1-azide (INA). INA can be activated by photosensitizing fluorochromes; by restricting these fluorochromes to the pellicle, [125I]INA labeling will selectively target non-GPI-anchored membrane-embedded proteins of the pellicle. We demonstrate here that three known membrane proteins of the pellicle can indeed be labeled by photosensitization with INA. In addition, this approach has identified a novel 22-kDa protein, named PhIL1 (photosensitized INA-labeled protein 1), with unexpected properties. While the INA labeling of PhIL1 is consistent with an integral membrane protein, the protein has neither a transmembrane domain nor predicted sites of lipid modification. PhIL1 is conserved in apicomplexan parasites and localizes to the parasite periphery, concentrated at the apical end just basal to the conoid. Detergent extraction and immunolocalization data suggest that PhIL1 associates with the parasite cytoskeleton.

Quantitative immunocytochemical localization of four immunodominant antigens of Toxoplasma gondii

1990 ◽  
Vol 48 (3) ◽  
pp. 946-947
Author(s):  
A. Bonhomme ◽  
F. Boulanger ◽  
S. Lebonvallet ◽  
N. Bonnet ◽  
L.M. Bharadwaj ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Surface Membrane ◽  
Surface Protein ◽  
Surface Proteins ◽  
Gold Complex ◽  
Image Analysis System ◽  
Thin Sections ◽  
Immunodominant Antigens ◽  
Analysis System ◽  
Major Surface

Four immunodominant antigens frequently observed in congenital, acquired and reactivated toxoplasmosis have been localized on Toxoplasma gondii ultrathin sections using four monoclonal antibodies (Mab GII9, IV47, IE10 II38) which detect membrane and cytoplasmic antigens. Thin sections as well as the whole surface of RH tachyzoïtes of Toxoplasma gondii are immunolabeled with the different Mab and Biotin-streptavidin-colloïdal gold complex. The quantitative analysis of immunogold labeling was performed with the help of a semi-automatic procedure developped by us, using a digital image analysis system (Bio 500-BIOCOM, les Ullis, FRANCE). The number of gold particles per unit surface are quantified inside three cellular compartments defined on the video screen : surface membrane, submembrane area and rhoptries.On the whole cell surface, proteins of 30 kDa (P30) detected with Mab GII9 were the major surface protein (Fig 1). By quantitative evaluation, they were 50 fold more abundant than P45-50kDa (recognized by Mab II38) proteins and 7 fold more abundant than P66-70kDa (recognized by Mab IE10) proteins. For the proteins of 28 kDa detected with Mab IV47 the labeling was very intensive in the submembrane area (Fig 3).

scholarly journals Raft microdomain localized in the luminal leaflet of inner membrane complex of living Toxoplasma gondii

2021 ◽  
Vol 100 (2) ◽  
pp. 151149
Author(s):  
Rikako Konishi ◽  
Yuna Kurokawa ◽  
Kanna Tomioku ◽  
Tatsunori Masatani ◽  
Xuenan Xuan ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Inner Membrane ◽  
Membrane Complex ◽  
Inner Membrane Complex

scholarly journals Toxoplasma gondii myosins B/C

2001 ◽  
Vol 155 (4) ◽  
pp. 613-624 ◽  
Author(s):  
Frédéric Delbac ◽  
Astrid Sänger ◽  
Eva M. Neuhaus ◽  
Rolf Stratmann ◽  
James W. Ajioka ◽  
...  
Keyword(s):  
Cell Division ◽  
Toxoplasma Gondii ◽  
Daughter Cell ◽  
Gliding Motility ◽  
Apicomplexan Parasites ◽  
Daughter Cells ◽  
Membrane Complex ◽  
Alternatively Spliced ◽  
Butanedione Monoxime ◽  
Inner Membrane Complex

In apicomplexan parasites, actin-disrupting drugs and the inhibitor of myosin heavy chain ATPase, 2,3-butanedione monoxime, have been shown to interfere with host cell invasion by inhibiting parasite gliding motility. We report here that the actomyosin system of Toxoplasma gondii also contributes to the process of cell division by ensuring accurate budding of daughter cells. T. gondii myosins B and C are encoded by alternatively spliced mRNAs and differ only in their COOH-terminal tails. MyoB and MyoC showed distinct subcellular localizations and dissimilar solubilities, which were conferred by their tails. MyoC is the first marker selectively concentrated at the anterior and posterior polar rings of the inner membrane complex, structures that play a key role in cell shape integrity during daughter cell biogenesis. When transiently expressed, MyoB, MyoC, as well as the common motor domain lacking the tail did not distribute evenly between daughter cells, suggesting some impairment in proper segregation. Stable overexpression of MyoB caused a significant defect in parasite cell division, leading to the formation of extensive residual bodies, a substantial delay in replication, and loss of acute virulence in mice. Altogether, these observations suggest that MyoB/C products play a role in proper daughter cell budding and separation.

scholarly journals Identification of the membrane receptor of a class XIV myosin in Toxoplasma gondii

2004 ◽  
Vol 165 (3) ◽  
pp. 383-393 ◽  
Author(s):  
Elizabeth Gaskins ◽  
Stacey Gilk ◽  
Nicolette DeVore ◽  
Tara Mann ◽  
Gary Ward ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Protein Complex ◽  
Integral Membrane Protein ◽  
Gliding Motility ◽  
Host Cells ◽  
Inner Membrane ◽  
Apicomplexan Parasites ◽  
Membrane Complex ◽  
Inner Membrane Complex ◽  
Two Stages

Apicomplexan parasites exhibit a unique form of substrate-dependent motility, gliding motility, which is essential during their invasion of host cells and during their spread between host cells. This process is dependent on actin filaments and myosin that are both located between the plasma membrane and two underlying membranes of the inner membrane complex. We have identified a protein complex in the apicomplexan parasite Toxoplasma gondii that contains the class XIV myosin required for gliding motility, TgMyoA, its associated light chain, TgMLC1, and two novel proteins, TgGAP45 and TgGAP50. We have localized this complex to the inner membrane complex of Toxoplasma, where it is anchored in the membrane by TgGAP50, an integral membrane glycoprotein. Assembly of the protein complex is spatially controlled and occurs in two stages. These results provide the first molecular description of an integral membrane protein as a specific receptor for a myosin motor, and further our understanding of the motile apparatus underlying gliding motility in apicomplexan parasites.

scholarly journals Gliding Associated Proteins Play Essential Roles during the Formation of the Inner Membrane Complex of Toxoplasma gondii

2016 ◽  
Vol 12 (2) ◽  
pp. e1005403 ◽  
Author(s):  
Clare R. Harding ◽  
Saskia Egarter ◽  
Matthew Gow ◽  
Elena Jiménez-Ruiz ◽  
David J. P. Ferguson ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Inner Membrane ◽  
Membrane Complex ◽  
Associated Proteins ◽  
Inner Membrane Complex

scholarly journals N-terminal palmitoylation is required for Toxoplasma gondii HSP20 inner membrane complex localization

2013 ◽  
Vol 1833 (6) ◽  
pp. 1329-1337 ◽  
Author(s):  
M.G. De Napoli ◽  
N. de Miguel ◽  
M. Lebrun ◽  
S.N.J. Moreno ◽  
S.O. Angel ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Inner Membrane ◽  
Membrane Complex ◽  
Inner Membrane Complex

scholarly journals A Novel Actin-Related Protein Is Associated with Daughter Cell Formation in Toxoplasma gondii

2008 ◽  
Vol 7 (9) ◽  
pp. 1500-1512 ◽  
Author(s):  
Jennifer L. Gordon ◽  
Wandy L. Beatty ◽  
L. David Sibley
Keyword(s):  
Cell Division ◽  
Toxoplasma Gondii ◽  
Daughter Cell ◽  
Cell Formation ◽  
The Body ◽  
Apicomplexan Parasites ◽  
Daughter Cells ◽  
Membrane Complex ◽  
Transport Vesicles ◽  
Inner Membrane Complex

ABSTRACT Cell division in Toxoplasma gondii occurs by an unusual budding mechanism termed endodyogeny, during which twin daughters are formed within the body of the mother cell. Cytokinesis begins with the coordinated assembly of the inner membrane complex (IMC), which surrounds the growing daughter cells. The IMC is compiled of both flattened membrane cisternae and subpellicular filaments composed of articulin-like proteins attached to underlying singlet microtubules. While proteins that comprise the elongating IMC have been described, little is known about its initial formation. Using Toxoplasma as a model system, we demonstrate that actin-like protein 1 (ALP1) is partially redistributed to the IMC at early stages in its formation. Immunoelectron microscopy localized ALP1 to a discrete region of the nuclear envelope, on transport vesicles, and on the nascent IMC of the daughter cells prior to the arrival of proteins such as IMC-1. The overexpression of ALP1 under the control of a strong constitutive promoter disrupted the formation of the daughter cell IMC, leading to delayed growth and defects in nuclear and apicoplast segregation. Collectively, these data suggest that ALP1 participates in the formation of daughter cell membranes during cell division in apicomplexan parasites.

A cytochemistry study of the inner membrane complex of the pellicle of tachyzoites of Toxoplasma gondii

1997 ◽  
Vol 83 (3) ◽  
pp. 252-256 ◽  
Author(s):  
E. J. T. de Melo ◽  
W. de Souza ◽  
E. J. T. de Melo ◽  
W. de Souza
Keyword(s):  
Toxoplasma Gondii ◽  
Inner Membrane ◽  
Membrane Complex ◽  
Inner Membrane Complex
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