title: The Ubiquitin Proteome of Toxoplasma gondii Reveals Roles for Protein Ubiquitination in Cell-Cycle Transitions.
abstract: Protein ubiquitination plays key roles in protein turnover, cellular signaling, and intracellular transport. The genome of Toxoplasma gondii encodes ubiquitination machinery, but the roles of this posttranslational modification (PTM) are unknown. To examine the prevalence and function of ubiquitination in T. gondii, we mapped the ubiquitin proteome of tachyzoites. Over 500 ubiquitin-modified proteins, with almost 1,000 sites, were identified on proteins with diverse localizations and functions. Enrichment analysis demonstrated that 35% of ubiquitinated proteins are cell-cycle regulated. Unexpectedly, most classic cell-cycle regulators conserved in T. gondii were not detected in the ubiquitinome. Furthermore, many ubiquitinated proteins localize to the cytoskeleton and inner membrane complex, a structure beneath the plasma membrane facilitating division and host invasion. Comparing the ubiquitinome with other PTM proteomes reveals waves of PTM enrichment during the cell cycle. Thus, T. gondii PTMs are implicated as critical regulators of cell division and cell-cycle transitions.
authors.affiliation: Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Natalie C
authors.initials: NC
authors.lastname: Silmon de Monerri
authors.affiliation: Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Rama R
authors.initials: RR
authors.lastname: Yakubu
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, CA 90095-1489, USA.
authors.forename: Allan L
authors.initials: AL
authors.lastname: Chen
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, CA 90095-1489, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Bradley
authors.affiliation: Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Department of Developmental & Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Nieves
authors.affiliation: Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Louis M
authors.initials: LM
authors.lastname: Weiss
authors.affiliation: Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA. Electronic address: kami.kim@einstein.yu.edu.
authors.forename: Kami
authors.initials: K
authors.lastname: Kim
mesh_terms: D002453:Cell Cycle; D052816:Foreskin; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008297:Male; D010802:Phylogeny; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D020543:Proteome / Q000032:analysis; D015800:Protozoan Proteins / Q000032:analysis / Q000378:metabolism*; D014122:Toxoplasma / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D025801:Ubiquitin / Q000032:analysis / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D020543:Proteome; D015800:Protozoan Proteins; D025801:Ubiquitin