Targeting Toxoplasma Tubules: Tubulin, Microtubules, and Associated Proteins in a Human Pathogen

Abstract

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. Additionally, a set of membrane-associated microtubules is essential for the elongated shape of invasive "zoites," and motility follows a spiral trajectory that reflects the path of these microtubules. Toxoplasma zoites also construct an intricate, tubulin-based apical structure, termed the conoid, which is important for host cell invasion and associates with proteins typically found in the flagellar apparatus. Last, microgametes specifically construct a microtubule-containing flagellar axoneme in order to fertilize macrogametes, permitting genetic recombination. The specialized roles of these microtubule populations are mediated by distinct sets of associated proteins. This review summarizes our current understanding of the role of tubulin, microtubule populations, and associated proteins in Toxoplasma; these components are used for both novel and broadly conserved processes that are essential for parasite survival.

The Ubiquitin Proteome of Toxoplasma gondii Reveals Roles for Protein Ubiquitination in Cell-Cycle Transitions

“…Ubiquitination of myosins may be important for rearrangement of the cytoskeleton or regulation of motor function. Tubulin is essential for parasite structure (Morrissette, 2015) and was also ubiquitinated. T. gondii has several microtubule structures with distinct functions: conoid and intraconoid microtubules, spindle microtubules, the centriole and subpellicular microtubules.…”

Translationally controlled tumor protein is required for the fast growth of Toxoplasma gondii and maintenance of its intracellular development

“…Among them, 483 genes were down‐regulated as a result of the Tg TCTP deficiency, and several significantly down‐regulated genes were associated with the pathway of growth and development. T‐complex testisexpressed 2‐related light chain (TGGT1_278790) is related to the dynein motor, molecular transport, and replication of Tg (41). Paralyzed flagella 2 (PF2) arrest‐specific protein 8/11 (TGGT1_248225) is a subunit of the dynein motor regulatory complex (42).…”

Toxoplasma gondii Tissue Cyst: Cyst Wall Incorporation Activity and Matrix Cytoskeleton Proteins Paving the Way to Nutrient Acquisition

“…Each microtubule subpopulation is organized for specific functions, such as the mitotic spindle, tracks for vesicular transport plus the basal body, and associated flagellar axoneme. In T. gondii, there are at least five discrete tubulin-based structures including the conoid, cortical microtubules, intraconoid microtubules, and centrioles, as well as a spindle in replicating parasites [19]. Studies may be required to confirm whether or not tissue cyst matrix cytoskeleton proteins originate from the parasite or from mammalian host cells during the parasitophorous vacuole formation.…”

“…Cytoskeleton proteins are indispensable components of a number of vital parasite structures and functions, like cell division, membrane and cytoplasmic architectures, parasite gliding motility (glideosome), and host-cell invasion [18][19][20]. Besides conventional cytoskeleton elements, many components of T. gondii are novel proteins.…”