Toxoplasma replication is inhibited by MMV676477 without development of resistance.

Protozoan parasites cause life-threatening infections in both humans and animals, including agriculturally significant livestock. Available treatments are typically narrow spectrum and are complicated by drug toxicity and the development of resistant parasites. Protozoan tubulin is an attractive target for the development of broad-spectrum antimitotic agents.

The tubulin database: Linking mutations, modifications, ligands and local interactions.

Microtubules are polymeric filaments, constructed of α-β tubulin heterodimers that underlie critical subcellular structures in eukaryotic organisms. Four homologous proteins (γ-, δ-, ε- and ζ-tubulin) additionally contribute to specialized microtubule functions. Although there is an immense volume of publicly available data pertaining to tubulins, it is difficult to assimilate all potentially relevant information across diverse organisms, isotypes, and categories of data.

The Tubulin Superfamily in Apicomplexan Parasites.

Microtubules and specialized microtubule-containing structures are assembled from tubulins, an ancient superfamily of essential eukaryotic proteins. Here, we use bioinformatic approaches to analyze features of tubulins in organisms from the phylum Apicomplexa. Apicomplexans are protozoan parasites that cause a variety of human and animal infectious diseases.

Systematic Analysis of Clemastine, a Candidate Apicomplexan Parasite-Selective Tubulin-Targeting Agent.

Apicomplexan parasites, such as , spp., spp., and spp.

Inhibiting parasite proliferation using a rationally designed anti-tubulin agent.

Infectious diseases caused by apicomplexan parasites remain a global public health threat. The presence of multiple ligand-binding sites in tubulin makes this protein an attractive target for anti-parasite drug discovery. However, despite remarkable successes as anti-cancer agents, the rational development of protozoan parasite-specific tubulin drugs has been hindered by a lack of structural and biochemical information on protozoan tubulins.

Auranofin Resistance in Decreases the Accumulation of Reactive Oxygen Species but Does Not Target Parasite Thioredoxin Reductase.

Auranofin, a reprofiled FDA-approved drug originally designed to treat rheumatoid arthritis, has emerged as a promising anti-parasitic drug. It induces the accumulation of reactive oxygen species (ROS) in parasites, including . We generated auranofin resistant lines through chemical mutagenesis to identify the molecular target of this drug.

A Toxoplasma gondii patatin-like phospholipase contributes to host cell invasion.

Toxoplasma gondii is an obligate intracellular parasite that can invade any nucleated cell of any warm-blooded animal. In a previous screen to identify virulence determinants, disruption of gene TgME49_305140 generated a T. gondii mutant that could not establish a chronic infection in mice.

The tubulin mutation database: A resource for the cytoskeleton community.

Over the last 40 years, the phenotypic consequences of point mutations to tubulin genes have been described in a wide variety of eukaryotes. A publicly available web-based catalog of all published point mutations to tubulin was assembled. Each entry records a specific substitution to a discrete tubulin, the species where the mutation was described, the associated phenotype, and provides hyperlinks to the parental amino acid sequence and citation(s) for the original research.

From B to A: making an essential cofactor in a human parasite.

Trypanosomatids are parasitic eukaryotic organisms that cause human disease. These organisms have complex lifestyles; cycling between vertebrate and insect hosts and alternating between two morphologies; a replicating form and an infective, nonreplicating one. Because trypanosomatids are one of the few organisms that do not synthesize the essential cofactor, heme, these parasites sequester the most common form, heme B, from their hosts.

Basal body structure and composition in the apicomplexans Toxoplasma and Plasmodium.

The phylum Apicomplexa encompasses numerous important human and animal disease-causing parasites, including the Plasmodium species, and Toxoplasma gondii, causative agents of malaria and toxoplasmosis, respectively. Apicomplexans proliferate by asexual replication and can also undergo sexual recombination. Most life cycle stages of the parasite lack flagella; these structures only appear on male gametes.

Extracellular Toxoplasma gondii tachyzoites metabolize and incorporate unnatural sugars into cellular proteins.

Toxoplasma gondii is an obligate intracellular parasite that infects all nucleated cell types in diverse warm-blooded organisms. Many of the surface antigens and effector molecules secreted by the parasite during invasion and intracellular growth are modified by glycans. Glycosylated proteins in the nucleus and cytoplasm have also been reported.

An ensemble of specifically targeted proteins stabilizes cortical microtubules in the human parasite Toxoplasma gondii.

Although all microtubules within a single cell are polymerized from virtually identical subunits, different microtubule populations carry out specialized and diverse functions, including directional transport, force generation, and cellular morphogenesis. Functional differentiation requires specific targeting of associated proteins to subsets or even subregions of these polymers. The cytoskeleton of Toxoplasma gondii, an important human parasite, contains at least five distinct tubulin-based structures.

Compartmentalized Toxoplasma EB1 bundles spindle microtubules to secure accurate chromosome segregation.

Toxoplasma gondii replicates asexually by a unique internal budding process characterized by interwoven closed mitosis and cytokinesis. Although it is known that the centrosome coordinates these processes, the spatiotemporal organization of mitosis remains poorly defined. Here we demonstrate that centrosome positioning around the nucleus may signal spindle assembly: spindle microtubules (MTs) are first assembled when the centrosome moves to the basal side and become extensively acetylated after the duplicated centrosomes reposition to the apical side.

Targeting Toxoplasma tubules: tubulin, microtubules, and associated proteins in a human pathogen.

Toxoplasma gondii is an obligate intracellular parasite that causes serious opportunistic infections, birth defects, and blindness in humans. Microtubules are critically important components of diverse structures that are used throughout the Toxoplasma life cycle. As in other eukaryotes, spindle microtubules are required for chromosome segregation during replication.

Diaryl and heteroaryl sulfides: synthesis via sulfenyl chlorides and evaluation as selective anti-breast-cancer agents.

A mild protocol for the synthesis of diaryl and heteroaryl sulfides is described. In a one-pot procedure, thiols are converted to sulfenyl chlorides and reacted with arylzinc reagents. This method tolerates functional groups including aryl fluorides and chlorides, ketones, as well as N-heterocycles including pyrimidines, imidazoles, tetrazoles, and oxadiazoles.

Stereospecific nickel-catalyzed cross-coupling reactions of alkyl Grignard reagents and identification of selective anti-breast-cancer agents.

Alkyl Grignard reagents that contain β-hydrogen atoms were used in a stereospecific nickel-catalyzed cross-coupling reaction to form C(sp(3))-C(sp(3)) bonds. Aryl Grignard reagents were also utilized to synthesize 1,1-diarylalkanes. Several compounds synthesized by this method exhibited selective inhibition of proliferation of MCF-7 breast cancer cells.

A SAS-6-like protein suggests that the Toxoplasma conoid complex evolved from flagellar components.

SAS-6 is required for centriole biogenesis in diverse eukaryotes. Here, we describe a novel family of SAS-6-like (SAS6L) proteins that share an N-terminal domain with SAS-6 but lack coiled-coil tails. SAS6L proteins are found in a subset of eukaryotes that contain SAS-6, including diverse protozoa and green algae.

Cell division in Apicomplexan parasites is organized by a homolog of the striated rootlet fiber of algal flagella.

Apicomplexa are intracellular parasites that cause important human diseases including malaria and toxoplasmosis. During host cell infection new parasites are formed through a budding process that parcels out nuclei and organelles into multiple daughters. Budding is remarkably flexible in output and can produce two to thousands of progeny cells.

SPM1 stabilizes subpellicular microtubules in Toxoplasma gondii.

We have identified two novel proteins that colocalize with the subpellicular microtubules in the protozoan parasite Toxoplasma gondii and named these proteins SPM1 and SPM2. These proteins have basic isoelectric points and both have homologs in other apicomplexan parasites. SPM1 contains six tandem copies of a 32-amino-acid repeat, whereas SPM2 lacks defined protein signatures.

α-Tubulin mutations alter oryzalin affinity and microtubule assembly properties to confer dinitroaniline resistance.

Plant and protozoan microtubules are selectively sensitive to dinitroanilines, which do not disrupt vertebrate or fungal microtubules. Tetrahymena thermophila is an abundant source of dinitroaniline-sensitive tubulin, and we have modified the single T. thermophila α-tubulin gene to create strains that solely express mutant α-tubulin in functional dimers.

A novel family of Toxoplasma IMC proteins displays a hierarchical organization and functions in coordinating parasite division.

Apicomplexans employ a peripheral membrane system called the inner membrane complex (IMC) for critical processes such as host cell invasion and daughter cell formation. We have identified a family of proteins that define novel sub-compartments of the Toxoplasma gondii IMC. These IMC Sub-compartment Proteins, ISP1, 2 and 3, are conserved throughout the Apicomplexa, but do not appear to be present outside the phylum.

MEC-17 is an alpha-tubulin acetyltransferase.

In most eukaryotic cells, subsets of microtubules are adapted for specific functions by post-translational modifications (PTMs) of tubulin subunits. Acetylation of the epsilon-amino group of K40 on alpha-tubulin is a conserved PTM on the luminal side of microtubules that was discovered in the flagella of Chlamydomonas reinhardtii. Studies on the significance of microtubule acetylation have been limited by the undefined status of the alpha-tubulin acetyltransferase.

Synthesis and evaluation of oryzalin analogs against Toxoplasma gondii.

The synthesis and evaluation of 20 dinitroanilines and related compounds against the obligate intracellular parasite Toxoplasma gondii is reported. Using in vitro cultures of parasites in human fibroblasts, we determined that most of these compounds selectively disrupted Toxoplasma microtubules, and several displayed sub-micromolar potency against the parasite. The most potent compound was N(1),N(1)-dipropyl-2,6-dinitro-4-(trifluoromethyl)-1,3-benzenediamine (18b), which displayed an IC(50) value of 36 nM against intracellular T.

RNG1 is a late marker of the apical polar ring in Toxoplasma gondii.

The asexually proliferating stages of apicomplexan parasites cause acute symptoms of diseases such as malaria, cryptosporidiosis and toxoplasmosis. These stages are characterized by the presence of two independent microtubule organizing centers (MTOCs). Centrioles are found at the poles of the intranuclear spindle.