title: TgVTC2 is involved in polyphosphate accumulation in Toxoplasma gondii.
abstract: Polyphosphate is found in every cell, having roles in diverse processes, including differentiation and response to stress. In this study, we characterize a Toxoplasma gondii mutant containing an insertion within the carboxy-terminal end of a homolog of Saccharomyces cerevisiae Vtc2p, a component of the polyphosphate synthetic machinery. Locus TgVTC2 encodes a 140kDa protein containing conserved SPX, VTC and transmembrane domains. TgVTC2 localizes in punctate spots within the cytoplasm that do not co-localize with known markers. The TgVTC2 mutant showed dramatically reduced polyphosphate accumulation, a defect restored by introduction of TgVTC2 to the mutant. Insertion within TgVTC2 resulted in increased transcript levels for two loci, including a putative FIKK kinase. These transcript levels were restored to wild-type levels upon complementation with the TgVTC2 locus. The TgVTC2 locus was refractory to knockout, and may be essential. Analysis of this TgVTC2 mutant will facilitate dissection of the T. gondii polyphosphate synthesis pathway.
authors.affiliation: Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Microbial Sciences Building Room 3345, 1550 Linden Drive, Madison, WI 53706, USA.
authors.forename: Peggy J
authors.initials: PJ
authors.lastname: Rooney
authors.forename: Lawrence
authors.initials: L
authors.lastname: Ayong
authors.forename: Crystal M
authors.initials: CM
authors.lastname: Tobin
authors.forename: Silvia N J
authors.initials: SN
authors.lastname: Moreno
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Knoll
mesh_terms: D003001:Cloning, Molecular; D017353:Gene Deletion; D056726:Genetic Association Studies; D005816:Genetic Complementation Test; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D011122:Polyphosphates / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D014122:Toxoplasma / Q000235:genetics / Q000378:metabolism*; D014123:Toxoplasmosis / Q000469:parasitology; D015854:Up-Regulation / Q000235:genetics
chemical_list: D018832:Molecular Chaperones; D011122:Polyphosphates; D015800:Protozoan Proteins; D011494:Protein Kinases