Redistribution of Parasite and Host Cell Membrane Components during Toxoplasma gondii Invasion.

The protozoan parasite Toxoplasma gondii is a representative of apicomplexan parasites that invades host cells through an unconventional motility mechanism. During host cell invasion it forms a specialized membrane-surrounded compartment that is called the parasitophorous vacuole. The interactions between the host cell and parasite membranes are complex and recent studies have revealed in more detail that both the host cell and the parasite membrane contribute to the formation of the parasitophorous vacuole. By using our a new specimen preparation technique that allows three-dimensional imaging of thick-sectioned internal cell structures with high-resolution, low-voltage field emission scanning electron microscopy, we were able to visualize continuous structural interactions of the host cell membrane with the parasite within the parasitophorous vacuole. Fibrous and tubular material extends from the host cell membrane and is connected to parasite membrane components. Shorter protrusions are also elaborated from the parasite. Several of these shorter fine protrusions connect to the fibrous material of the host cell membrane. The elaborate network may be used for modifications of the parasitophorous vacuole membrane that will allow utilization of nutrients from the host cell by the parisite while it is being protected from host cell attacks. The structural interactions between parasite and host cells undergo time-dependent changes, and a fission pore is the most prominent structure left connecting the parasite with the host cell. The fission pore is anchored in the host cell by thick structural components of unknown nature. The new information gained with this technique includes structural details of fibrous and tubular material that is continuous between the parasite and host cell and can be imaged in three dimensions. We present this technique as a tool to investigate more fully the complex structural interactions of the host cell and the parasite residing in the parasitophorous vacuole.

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Faculty Opinions recommendation of The Bacillus subtilis quorum-sensing molecule CSF contributes to intestinal homeostasis via OCTN2, a host cell membrane transporter.

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

10.3410/f.1087414.541922 ◽

2007 ◽

Author(s):

June Kwon-Chung

Keyword(s):

Bacillus Subtilis ◽

Quorum Sensing ◽

Cell Membrane ◽

Host Cell ◽

Membrane Transporter ◽

Intestinal Homeostasis ◽

Host Cell Membrane ◽

Quorum Sensing Molecule

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Exaptation of Retroviral Syncytin for Development of Syncytialized Placenta, Its Limited Homology to the SARS-CoV-2 Spike Protein and Arguments against Disturbing Narrative in the Context of COVID-19 Vaccination

Biology ◽

10.3390/biology10030238 ◽

2021 ◽

Vol 10 (3) ◽

pp. 238

Author(s):

Malgorzata Kloc ◽

Ahmed Uosef ◽

Jacek Z. Kubiak ◽

Rafik M. Ghobrial

Keyword(s):

Cell Membrane ◽

Host Cell ◽

Envelope Glycoprotein ◽

Mammalian Species ◽

Viral Envelope ◽

Spike Protein ◽

Mammalian Evolution ◽

Trophoblast Cells ◽

Host Cell Membrane ◽

Uterine Endometrium

Human placenta formation relies on the interaction between fused trophoblast cells of the embryo with uterine endometrium. The fusion between trophoblast cells, first into cytotrophoblast and then into syncytiotrophoblast, is facilitated by the fusogenic protein syncytin. Syncytin derives from an envelope glycoprotein (ENV) of retroviral origin. In exogenous retroviruses, the envelope glycoproteins coded by env genes allow fusion of the viral envelope with the host cell membrane and entry of the virus into a host cell. During mammalian evolution, the env genes have been repeatedly, and independently, captured by various mammalian species to facilitate the formation of the placenta. Such a shift in the function of a gene, or a trait, for a different purpose during evolution is called an exaptation (co-option). We discuss the structure and origin of the placenta, the fusogenic and non-fusogenic functions of syncytin, and the mechanism of cell fusion. We also comment on an alleged danger of the COVID-19 vaccine based on the presupposed similarity between syncytin and the SARS-CoV-2 spike protein.

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Intracellular host cell membrane remodelling induced by SARS‐CoV‐2 infection in vitro

Biology of the Cell ◽

10.1111/boc.202000146 ◽

2021 ◽

Author(s):

Lucio Ayres Caldas ◽

Fabiana Avila Carneiro ◽

Fabio Luis Monteiro ◽

Ingrid Augusto ◽

Luiza Mendonça Higa ◽

...

Keyword(s):

Cell Membrane ◽

Host Cell ◽

Host Cell Membrane

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Transbilayer phospholipid asymmetry in Plasmodium knowlesi-infected host cell membrane

Science ◽

10.1126/science.7233198 ◽

1981 ◽

Vol 212 (4498) ◽

pp. 1047-1049 ◽

Cited By ~ 51

Author(s):

C. Gupta ◽

G. Mishra

Keyword(s):

Cell Membrane ◽

Host Cell ◽

Plasmodium Knowlesi ◽

Infected Host ◽

Host Cell Membrane ◽

Infected Host Cell ◽

Phospholipid Asymmetry

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The Photorhabdus asymbiotica virulence cassettes deliver protein effectors directly into target eukaryotic cells

eLife ◽

10.7554/elife.46259 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 8

Author(s):

Isabella Vlisidou ◽

Alexia Hapeshi ◽

Joseph RJ Healey ◽

Katie Smart ◽

Guowei Yang ◽

...

Keyword(s):

Cell Membrane ◽

Host Cell ◽

Small Molecule ◽

Rho Gtpase ◽

Eukaryotic Cells ◽

Host Cell Membrane ◽

Western Blots ◽

Insect Pathogen ◽

Protein Toxins ◽

Delivery Mechanism

Photorhabdus is a highly effective insect pathogen and symbiont of insecticidal nematodes. To exert its potent insecticidal effects, it elaborates a myriad of toxins and small molecule effectors. Among these, the Photorhabdus Virulence Cassettes (PVCs) represent an elegant self-contained delivery mechanism for diverse protein toxins. Importantly, these self-contained nanosyringes overcome host cell membrane barriers, and act independently, at a distance from the bacteria itself. In this study, we demonstrate that Pnf, a PVC needle complex associated toxin, is a Rho-GTPase, which acts via deamidation and transglutamination to disrupt the cytoskeleton. TEM and Western blots have shown a physical association between Pnf and its cognate PVC delivery mechanism. We demonstrate that for Pnf to exert its effect, translocation across the cell membrane is absolutely essential.

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