Diverse Roles of TgMIC1/4/6 in the Toxoplasma Infection

Toxoplasma gondii microneme is a specialized secretory organelle that discharges its contents at the apical tip of this apicomplexan parasite in a sequential and regulated manner. Increasing number of studies on microneme proteins (MICs) have shown them as a predominant and important role in host cell attachment, invasion, motility and pathogenesis. In this review, we summarize the research advances in one of the most important MICs complexes, TgMIC1/4/6, which will contribute to improve the understanding of the molecular mechanism of T. gondii infection and provide a theoretical basis for the effective control against T. gondii.

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O-fucosylation of thrombospondin-like repeats is required for processing of MIC2 and for efficient host cell invasion by Toxoplasma gondii tachyzoites

10.1101/382515 ◽

2018 ◽

Cited By ~ 2

Author(s):

Giulia Bandini ◽

Deborah R. Leon ◽

Carolin M. Hoppe ◽

Yue Zhang ◽

Carolina Agop-Nersesian ◽

...

Keyword(s):

Toxoplasma Gondii ◽

Host Cell ◽

Secretory Pathway ◽

Cell Attachment ◽

Host Cells ◽

Type I ◽

Human Foreskin Fibroblasts ◽

Genes Encoding ◽

Host Cell Attachment ◽

Glycosylation Pathway

AbstractToxoplasma gondii is an intracellular parasite that causes disseminated infections which can lead to neurological damage in fetuses and immunocompromised individuals. Microneme protein 2 (MIC2)2, a member of the thrombospondin-related anonymous protein (TRAP) family, is a secreted protein important for motility, host cell attachment, invasion, and egress. MIC2 contains six thrombospondin type I repeats (TSRs) that are modified by C-mannose and O-fucose in Plasmodium spp. and mammals.Here we used mass spectrometry to show that the four TSRs in T. gondii MIC2 with protein O-fucosyltransferase 2 (POFUT2) acceptor sites are modified by a dHexHex disaccharide, while Trp residues within three TSRs are also modified with C-mannose. Disruption of genes encoding either pofut2 or nucleotide sugar transporter 2 (nst2), the putative GDP-fucose transporter, results in loss of MIC2 O-fucosylation, as detected by an antibody against the GlcFuc disaccharide, and markedly reduced cellular levels of MIC2. Furthermore, in 10-15% of the Δpofut2 or Δnst2 vacuoles, MIC2 accumulates earlier in the secretory pathway rather than localizing to micronemes. Dissemination of tachyzoites in human foreskin fibroblasts is reduced in these knockouts, which both show defects in attachment to and invasion of host cells comparable to the phenotype observed in the Βmic2.These results, which show O-fucosylation of TSRs is required for efficient processing of MIC2 and for normal parasite invasion, are consistent with the recent demonstration that P. falciparum Δpofut2 has decreased virulence and support a conserved role for this glycosylation pathway in quality control of TSR-containing proteins in eukaryotes.

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TgTKL1 Is a Unique Plant-Like Nuclear Kinase That Plays an Essential Role in Acute Toxoplasmosis

mBio ◽

10.1128/mbio.00301-18 ◽

2018 ◽

Vol 9 (2) ◽

Cited By ~ 2

Author(s):

Joseph M. Varberg ◽

Isabelle Coppens ◽

Gustavo Arrizabalaga ◽

Rajshekhar Y. Gaji

Keyword(s):

Toxoplasma Gondii ◽

Tyrosine Kinase ◽

Host Cell ◽

Essential Role ◽

Cell Attachment ◽

Protozoan Parasite ◽

Lytic Cycle ◽

Host Cell Attachment ◽

Acute Toxoplasmosis ◽

Insight Into

ABSTRACT In the protozoan parasite Toxoplasma gondii , protein kinases have been shown to play key roles in regulating parasite motility, invasion, replication, egress, and survival within the host. The tyrosine kinase-like (TKL) family of proteins are an unexplored set of kinases in Toxoplasma . Of the eight annotated TKLs in the Toxoplasma genome, a recent genome-wide loss-of-function screen showed that six are important for tachyzoite fitness. By utilizing an endogenous tagging approach, we showed that these six T. gondii TKLs (TgTKLs) localize to various subcellular compartments, including the nucleus, the cytosol, the inner membrane complex, and the Golgi apparatus. To gain insight into the function of TKLs in Toxoplasma , we first characterized TgTKL1, which contains the plant-like enhanced disease resistance 1 (EDR1) domain and localizes to the nucleus. TgTKL1 knockout parasites displayed significant defects in progression through the lytic cycle; we show that the defects were due to specific impairment of host cell attachment. Transcriptomics analysis identified over 200 genes of diverse functions that were differentially expressed in TgTKL1 knockout parasites. Importantly, numerous genes implicated in host cell attachment and invasion were among those most significantly downregulated, resulting in defects in microneme secretion and processing. Significantly, all of the mice inoculated intraperitoneally with TgTKL1 knockout parasites survived the infection, suggesting that TgTKL1 plays an essential role in acute toxoplasmosis. Together, these findings suggest that TgTKL1 mediates a signaling pathway that regulates the expression of multiple factors required for parasite virulence, underscoring the potential of this kinase as a novel therapeutic target. IMPORTANCE Toxoplasma gondii is a protozoan parasite that can cause chronic and life-threatening disease in mammals; new drugs are greatly needed for treatment. One attractive group of drug targets consists of parasite kinases containing unique features that distinguish them from host proteins. In this report, we identify and characterize a previously unstudied kinase, TgTKL1, that localizes to the nucleus and contains a domain architecture unique to plants and protozoa. By disrupting TgTKL1, we showed that this kinase is required for the proper expression of hundreds of genes, including many that are required for the parasite to gain entry into the host cell. Specifically, parasites lacking TgTKL1 have defects in host cell attachment, resulting in impaired growth in vitro and a complete loss of virulence in mice. This report provides insight into the importance of the parasite tyrosine kinase-like kinases and establishes TgTKL1 as a novel and essential virulence factor in Toxoplasma .

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ROP9, MIC3, and SAG2 are heparin-binding proteins in Toxoplasma gondii and involved in host cell attachment and invasion

Acta Tropica ◽

10.1016/j.actatropica.2019.01.001 ◽

2019 ◽

Vol 192 ◽

pp. 22-29 ◽

Cited By ~ 4

Author(s):

Dongchao Zhang ◽

Ning Jiang ◽

Qijun Chen

Keyword(s):

Toxoplasma Gondii ◽

Host Cell ◽

Binding Proteins ◽

Cell Attachment ◽

Heparin Binding ◽

Host Cell Attachment

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Phage display as a tool for investigating Toxoplasma gondii host cell attachment

Biochemical Society Transactions ◽

10.1042/bst028a483a ◽

2000 ◽

Vol 28 (5) ◽

pp. A483-A483

Author(s):

S. A. Robinson ◽

J. E. Smith ◽

P. A. Millner

Keyword(s):

Toxoplasma Gondii ◽

Phage Display ◽

Host Cell ◽

Cell Attachment ◽

Host Cell Attachment

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Molecular Mechanism by Which Surface Antigen HP0197 Mediates Host Cell Attachment in the Pathogenic BacteriaStreptococcus suis

Journal of Biological Chemistry ◽

10.1074/jbc.m112.388686 ◽

2012 ◽

Vol 288 (2) ◽

pp. 956-963 ◽

Cited By ~ 11

Author(s):

Zeng-zhi Yuan ◽

Xiao-jie Yan ◽

An-ding Zhang ◽

Bo Chen ◽

Yue-quan Shen ◽

...

Keyword(s):

Host Cell ◽

Molecular Mechanism ◽

Surface Antigen ◽

Cell Attachment ◽

Host Cell Attachment

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Faculty Opinions recommendation of Host cell attachment elicits posttranscriptional regulation in infecting enteropathogenic bacteria.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.727315310.793529137 ◽

2017 ◽

Author(s):

Cynthia M Sharma

Keyword(s):

Host Cell ◽

Posttranscriptional Regulation ◽

Cell Attachment ◽

Enteropathogenic Bacteria ◽

Host Cell Attachment

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Toxoplasma gondii Rhoptry Discharge Correlates with Activation of the Early Growth Response 2 Host Cell Transcription Factor

Infection and Immunity ◽

10.1128/iai.01447-07 ◽

2008 ◽

Vol 76 (10) ◽

pp. 4703-4712 ◽

Cited By ~ 32

Author(s):

Eric D. Phelps ◽

Kristin R. Sweeney ◽

Ira J. Blader

Keyword(s):

Transcription Factor ◽

Toxoplasma Gondii ◽

Host Cell ◽

Growth Response ◽

Neospora Caninum ◽

Early Growth ◽

Apicomplexan Parasite ◽

Host Cells ◽

Early Growth Response ◽

Cell Extracts

ABSTRACT Toxoplasma gondii is a ubiquitous apicomplexan parasite that can cause severe disease in fetuses and immune-compromised patients. Rhoptries, micronemes, and dense granules, which are secretory organelles unique to Toxoplasma and other apicomplexan parasites, play critical roles in parasite growth and virulence. To understand how these organelles modulate infected host cells, we sought to identify host cell transcription factors triggered by their release. Early growth response 2 (EGR2) is a host cell transcription factor that is rapidly upregulated and activated in Toxoplasma-infected cells but not in cells infected with the closely related apicomplexan parasite Neospora caninum. EGR2 upregulation occurred only when live parasites were in direct contact with the host cell and not from exposure to cell extracts that contain dense granule or micronemal proteins. When microneme-mediated attachment was blocked by pretreating parasites with a calcium chelator, EGR2 expression was significantly reduced. In contrast, when host cells were infected with parasites in the presence of cytochalasin D, which allows rhoptry secretion but prevents parasite invasion, EGR2 was activated. Finally, we demonstrate that Toxoplasma activation of host p38 mitogen-activated protein kinase is necessary but not sufficient for EGR2 activation. Collectively, these data indicate that EGR2 is specifically upregulated by a parasite-derived secreted factor that is most likely a resident rhoptry protein.

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A structure-based rationale for sialic acid independent host-cell entry of Sosuga virus

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1906717116 ◽

2019 ◽

Vol 116 (43) ◽

pp. 21514-21520 ◽

Cited By ~ 3

Author(s):

Alice J. Stelfox ◽

Thomas A. Bowden

Keyword(s):

Sialic Acid ◽

Host Cell ◽

Receptor Binding ◽

Cell Attachment ◽

Cell Entry ◽

Head Region ◽

Close Proximity ◽

Host Cell Attachment ◽

Host Cell Entry

The bat-borne paramyxovirus, Sosuga virus (SosV), is one of many paramyxoviruses recently identified and classified within the newly established genus Pararubulavirus, family Paramyxoviridae. The envelope surface of SosV presents a receptor-binding protein (RBP), SosV-RBP, which facilitates host-cell attachment and entry. Unlike closely related hemagglutinin neuraminidase RBPs from other genera of the Paramyxoviridae, SosV-RBP and other pararubulavirus RBPs lack many of the stringently conserved residues required for sialic acid recognition and hydrolysis. We determined the crystal structure of the globular head region of SosV-RBP, revealing that while the glycoprotein presents a classical paramyxoviral six-bladed β-propeller fold and structurally classifies in close proximity to paramyxoviral RBPs with hemagglutinin-neuraminidase (HN) functionality, it presents a receptor-binding face incongruent with sialic acid recognition. Hemadsorption and neuraminidase activity analysis confirms the limited capacity of SosV-RBP to interact with sialic acid in vitro and indicates that SosV-RBP undergoes a nonclassical route of host-cell entry. The close overall structural conservation of SosV-RBP with other classical HN RBPs supports a model by which pararubulaviruses only recently diverged from sialic acid binding functionality.

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Complementation of the fadA Mutation in Fusobacterium nucleatum Demonstrates that the Surface-Exposed Adhesin Promotes Cellular Invasion and Placental Colonization

Infection and Immunity ◽

10.1128/iai.00209-09 ◽

2009 ◽

Vol 77 (7) ◽

pp. 3075-3079 ◽

Cited By ~ 48

Author(s):

Akihiko Ikegami ◽

Peter Chung ◽

Yiping W. Han

Keyword(s):

Host Cell ◽

Cell Attachment ◽

Adverse Pregnancy Outcome ◽

Fusobacterium Nucleatum ◽

Host Cells ◽

Mouse Placenta ◽

Host Cell Attachment ◽

Adverse Pregnancy

ABSTRACT Fusobacterium nucleatum is a gram-negative oral anaerobe implicated in periodontal disease and adverse pregnancy outcome. The organism colonizes the mouse placenta, causing localized infection and inflammation. The mechanism of placental colonization has not been elucidated. Previous studies identified a novel adhesin from F. nucleatum, FadA, as being involved in the attachment and invasion of host cells. The fadA deletion mutant F. nucleatum 12230 US1 was defective in host cell attachment and invasion in vitro, but it also exhibited pleiotropic effects with altered cell morphology and growth rate. In this study, a fadA-complementing clone, F. nucleatum 12230 USF81, was constructed. The expression of FadA on USF81 was confirmed by Western blotting and immunofluorescent labeling. USF81 restored host cell attachment and invasion activities. The ability of F. nucleatum 12230, US1, and USF81 to colonize the mouse placenta was examined. US1 was severely defective in placental colonization compared to the wild type and USF81. Thus, FadA plays an important role in F. nucleatum colonization in vivo. These results also represent the first complementation studies for F. nucleatum. FadA may be a therapeutic target for preventing F. nucleatum colonization of the host.

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