title: Proteomic analysis of the acidocalcisome, an organelle conserved from bacteria to human cells.
abstract: Acidocalcisomes are acidic organelles present in a diverse range of organisms from bacteria to human cells. In this study acidocalcisomes were purified from the model organism Trypanosoma brucei, and their protein composition was determined by mass spectrometry. The results, along with those that we previously reported, show that acidocalcisomes are rich in pumps and transporters, involved in phosphate and cation homeostasis, and calcium signaling. We validated the acidocalcisome localization of seven new, putative, acidocalcisome proteins (phosphate transporter, vacuolar H+-ATPase subunits a and d, vacuolar iron transporter, zinc transporter, polyamine transporter, and acid phosphatase), confirmed the presence of six previously characterized acidocalcisome proteins, and validated the localization of five novel proteins to different subcellular compartments by expressing them fused to epitope tags in their endogenous loci or by immunofluorescence microscopy with specific antibodies. Knockdown of several newly identified acidocalcisome proteins by RNA interference (RNAi) revealed that they are essential for the survival of the parasites. These results provide a comprehensive insight into the unique composition of acidocalcisomes of T. brucei, an important eukaryotic pathogen, and direct evidence that acidocalcisomes are especially adapted for the accumulation of polyphosphate.
authors.affiliation: Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America.
authors.forename: Guozhong
authors.initials: G
authors.lastname: Huang
authors.affiliation: Department of Biology, Georgia State University, Atlanta, Georgia, United States of America.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Ulrich
authors.affiliation: Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America.
authors.forename: Melissa
authors.initials: M
authors.lastname: Storey
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America.
authors.forename: Darryl
authors.initials: D
authors.lastname: Johnson
authors.affiliation: Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America.
authors.forename: Julie
authors.initials: J
authors.lastname: Tischer
authors.affiliation: Department of Biology, Georgia State University, Atlanta, Georgia, United States of America.
authors.forename: Javier A
authors.initials: JA
authors.lastname: Tovar
authors.affiliation: Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America.
authors.forename: Silvia N J
authors.initials: SN
authors.lastname: Moreno
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America.
authors.forename: Ron
authors.initials: R
authors.lastname: Orlando
authors.affiliation: Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America.
authors.forename: Roberto
authors.initials: R
authors.lastname: Docampo
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000502:physiology; D002412:Cations / Q000378:metabolism; D002478:Cells, Cultured; D006706:Homeostasis / Q000502:physiology; D013058:Mass Spectrometry; D026901:Membrane Transport Proteins / Q000378:metabolism*; D015388:Organelles / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D040901:Proteomics; D015800:Protozoan Proteins / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000166:cytology* / Q000378:metabolism
chemical_list: D002412:Cations; D026901:Membrane Transport Proteins; D010710:Phosphates; D015800:Protozoan Proteins