title: The acidocalcisome vacuolar transporter chaperone 4 catalyzes the synthesis of polyphosphate in insect-stages of Trypanosoma brucei and T. cruzi.
abstract: Polyphosphate is a polymer of inorganic phosphate found in both prokaryotes and eukaryotes. Polyphosphate typically accumulates in acidic, calcium-rich organelles known as acidocalcisomes, and recent research demonstrated that vacuolar transporter chaperone 4 catalyzes its synthesis in yeast. The human pathogens Trypanosoma brucei and T. cruzi possess vacuolar transporter chaperone 4 homologs. We demonstrate that T. cruzi vacuolar transporter chaperone 4 localizes to acidocalcisomes of epimastigotes by immunofluorescence and immuno-electron microscopy and that the recombinant catalytic region of the T. cruzi enzyme is a polyphosphate kinase. RNA interference of the T. brucei enzyme in procyclic form parasites reduced short chain polyphosphate levels and resulted in accumulation of pyrophosphate. These results suggest that this trypanosome enzyme is an important component of a polyphosphate synthase complex that utilizes ATP to synthesize and translocate polyphosphate to acidocalcisomes in insect stages of these parasites.
authors.affiliation: Department of Cellular Biology, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA; Department of Biology, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Ulrich
authors.forename: Noelia
authors.initials: N
authors.lastname: Lander
authors.forename: Samarchith P
authors.initials: SP
authors.lastname: Kurup
authors.forename: Laura
authors.initials: L
authors.lastname: Reiss
authors.forename: Jessica
authors.initials: J
authors.lastname: Brewer
authors.forename: Lia C
authors.initials: LC
authors.lastname: Soares Medeiros
authors.forename: Kildare
authors.initials: K
authors.lastname: Miranda
authors.forename: Roberto
authors.initials: R
authors.lastname: Docampo
mesh_terms: D026901:Membrane Transport Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000378:metabolism*; D011122:Polyphosphates / Q000378:metabolism*; D036702:Quassins; D017422:Sequence Analysis, DNA; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000378:metabolism*; D014349:Trypanosoma cruzi / Q000201:enzymology* / Q000378:metabolism*; D014617:Vacuoles / Q000201:enzymology* / Q000378:metabolism
chemical_list: D026901:Membrane Transport Proteins; D018832:Molecular Chaperones; D011122:Polyphosphates; D036702:Quassins; C049071:12-dehydro-6alpha-senecioyloxychaparrin; D017856:Phosphotransferases (Phosphate Group Acceptor); C022424:polyphosphate kinase
keywords: calcium; epimastigotes; procyclic forms