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Tag: Toxoplasma

Toxoplasma chitinase-like protein orchestrates cyst wall glycosylation to facilitate effector export and cyst turnover

Donna Huber on January 29, 2025

  Toxoplasma bradyzoites reside in tissue cysts that undergo cycles of expansion, rupture, and release to foster chronic infection. The glycosylated cyst wall acts as a protective barrier, although the processes responsible for formation, remodeling, and turnover are not understood. Herein, we identify a noncanonical chitinase-like enzyme TgCLP1 that localizes to micronemes and is targeted …

Trainee Spotlight: Kaelynn Parker

Donna Huber on July 30, 2024

I'm Kaelynn Parker and I'm from Virginia where I received my BS in biology from the University of Mary Washington. I'm a cellular biology Ph.D. student in Deigo Huet's laboratory. What made you want to study science? I took a genetic course at Germanna Community College as an elective while pursuing an associate’s degree part-time …

Seeing the unseen: illuminating Toxoplasma gondii’s metabolic manipulation

Donna Huber on July 12, 2024

Intracellular infection by a pathogen induces significant rewiring of host cell signaling and biological processes. Understanding how an intracellular pathogen such as Toxoplasma gondii modulates host cell metabolism with single-cell resolution has been challenged by the variability of infection within cultures and difficulties in separating host and parasite metabolic processes. A new study from Gallego-Lopez …

The Toxoplasma oxygen-sensing protein, TgPhyA, is required for resistance to interferon gamma-mediated nutritional immunity in mice

Donna Huber on June 10, 2024

  As Toxoplasma gondii disseminates through its host, the parasite must sense and adapt to its environment and scavenge nutrients. Oxygen (O2) is one such environmental factor and cytoplasmic prolyl 4-hydroxylases (PHDs) are evolutionarily conserved O2 cellular sensing proteins that regulate responses to changes in O2 availability. Toxoplasma expresses 2 PHDs. One of them, TgPHYa …

Massive invasion of organellar DNA drives nuclear genome evolution in Toxoplasma

Donna Huber on November 2, 2023

  Toxoplasma gondii is a zoonotic protist pathogen that infects up to one third of the human population. This apicomplexan parasite contains three genome sequences: nuclear (65 Mb); plastid organellar, ptDNA (35 kb); and mitochondrial organellar, mtDNA (5.9 kb of non-repetitive sequence). We find that the nuclear genome contains a significant amount of NUMTs (nuclear integrants …

Temporal and thermal profiling of the Toxoplasma proteome implicates parasite Protein Phosphatase 1 in the regulation of Ca 2+-responsive pathways

Donna Huber on August 17, 2022

Apicomplexan parasites cause persistent mortality and morbidity worldwide through diseases including malaria, toxoplasmosis, and cryptosporidiosis. Ca2+ signaling pathways have been repurposed in these eukaryotic pathogens to regulate parasite-specific cellular processes governing the replicative and lytic phases of the infectious cycle, as well as the transition between them. Despite the presence of conserved Ca2+-responsive proteins, little is …

Toxoplasma bradyzoites exhibit physiological plasticity of calcium and energy stores controlling motility and egress

Donna Huber on December 3, 2021

Toxoplasma gondii has evolved different developmental stages for disseminating during acute infection (i.e. tachyzoites) and for establishing chronic infection (i.e. bradyzoites). Calcium ion (Ca2+) signaling tightly regulates the lytic cycle of tachyzoites by controlling microneme secretion and motility to drive egress and cell invasion. However, the roles of Ca2+ signaling pathways in bradyzoites remain largely unexplored. Here …

A terminal α3-galactose modification regulates an E3 ubiquitin ligase subunit in Toxoplasma gondii

Donna Huber on May 15, 2020

Skp1, a subunit of E3 Skp1/Cullin-1/F-box protein ubiquitin ligases, is modified by a prolyl hydroxylase that mediates O2-regulation of the social amoeba Dictyostelium and the parasite Toxoplasma gondii. The full effect of hydroxylation requires modification of the hydroxyproline by a pentasaccharide that, in Dictyostelium, influences Skp1 structure to favor assembly of Skp1/F-box protein subcomplexes. In Toxoplasma, the presence of a contrasting …

Protozoan persister-like cells and drug treatment failure

Donna Huber on August 23, 2019

Antimicrobial treatment failure threatens our ability to control infections. In addition to antimicrobial resistance, treatment failures are increasingly understood to derive from cells that survive drug treatment without selection of genetically heritable mutations. Parasitic protozoa, such as Plasmodium species that cause malaria, Toxoplasma gondii and kinetoplastid protozoa, including Trypanosoma cruzi and Leishmaniaspp., cause millions of deaths globally. These organisms can evolve drug …

Toxoplasma F-box protein 1 is required for daughter cell scaffold function during parasite replication

Donna Huber on July 26, 2019

By binding to the adaptor protein SKP1 and serving as substrate receptors for the Skp1, Cullin, F-box E3 ubiquitin ligase complex, F-box proteins regulate critical cellular processes including cell cycle progression and membrane trafficking. While F-box proteins are conserved throughout eukaryotes and are well studied in yeast, plants, and animals, studies in parasitic protozoa are …