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Docampo R. Advances in the cellular biology, biochemistry, and molecular biology of acidocalcisomes. Microbiol Mol Biol Rev 2024; 88:e0004223. [PMID: 38099688 PMCID: PMC10966946 DOI: 10.1128/mmbr.00042-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2024] Open
Abstract
SUMMARYAcidocalcisomes are organelles conserved during evolution and closely related to the so-called volutin granules of bacteria and archaea, to the acidocalcisome-like vacuoles of yeasts, and to the lysosome-related organelles of animal species. All these organelles have in common their acidity and high content of polyphosphate and calcium. They are characterized by a variety of functions from storage of phosphorus and calcium to roles in Ca2+ signaling, osmoregulation, blood coagulation, and inflammation. They interact with other organelles through membrane contact sites or by fusion, and have several enzymes, pumps, transporters, and channels.
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Affiliation(s)
- Roberto Docampo
- Department of Cellular Biology, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
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2
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Strenkert D, Schmollinger S, Hu Y, Hofmann C, Holbrook K, Liu HW, Purvine SO, Nicora CD, Chen S, Lipton MS, Northen TR, Clemens S, Merchant SS. Cysteine: an ancestral Cu binding ligand in green algae? BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.15.532757. [PMID: 36993560 PMCID: PMC10055113 DOI: 10.1101/2023.03.15.532757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Growth of Chlamydomonas reinhardtii in zinc (Zn) limited medium leads to disruption of copper (Cu) homeostasis, resulting in up to 40-fold Cu over-accumulation relative to its typical Cu quota. We show that Chlamydomonas controls its Cu quota by balancing Cu import and export, which is disrupted in a Zn deficient cell, thus establishing a mechanistic connection between Cu and Zn homeostasis. Transcriptomics, proteomics and elemental profiling revealed that Zn-limited Chlamydomonas cells up-regulate a subset of genes encoding "first responder" proteins involved in sulfur (S) assimilation and consequently accumulate more intracellular S, which is incorporated into L-cysteine, γ-glutamylcysteine and homocysteine. Most prominently, in the absence of Zn, free L-cysteine is increased ~80-fold, corresponding to ~ 2.8 × 10 9 molecules/cell. Interestingly, classic S-containing metal binding ligands like glutathione and phytochelatins do not increase. X-ray fluorescence microscopy showed foci of S accumulation in Zn-limited cells that co-localize with Cu, phosphorus and calcium, consistent with Cu-thiol complexes in the acidocalcisome, the site of Cu(I) accumulation. Notably, cells that have been previously starved for Cu do not accumulate S or Cys, causally connecting cysteine synthesis with Cu accumulation. We suggest that cysteine is an in vivo Cu(I) ligand, perhaps ancestral, that buffers cytosolic Cu.
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Abstract
Acidocalcisomes are electron-dense organelles rich in polyphosphate and inorganic and organic cations that are acidified by proton pumps, and possess several channels, pumps, and transporters. They are present in bacteria and eukaryotes and have been studied in greater detail in trypanosomatids. Biogenesis studies of trypanosomatid acidocalcisomes found that they share properties with lysosome-related organelles of animal cells. In addition to their described roles in autophagy, cation and phosphorus storage, osmoregulation, pH homeostasis, and pathogenesis, recent studies have defined the role of these organelles in phosphate utilization, calcium ion (Ca2+ ) signaling, and bioenergetics, and will be the main subject of this review.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Guozhong Huang
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
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4
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Ramakrishnan S, Baptista RP, Asady B, Huang G, Docampo R. TbVps41 regulates trafficking of endocytic but not biosynthetic cargo to lysosomes of bloodstream forms of Trypanosoma brucei. FASEB J 2021; 35:e21641. [PMID: 34041791 DOI: 10.1096/fj.202100487r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/15/2021] [Accepted: 04/19/2021] [Indexed: 11/11/2022]
Abstract
The bloodstream stage of Trypanosoma brucei, the causative agent of African trypanosomiasis, is characterized by its high rate of endocytosis, which is involved in remodeling of its surface coat. Here we present evidence that RNAi-mediated expression down-regulation of vacuolar protein sorting 41 (Vps41), a component of the homotypic fusion and vacuole protein sorting (HOPS) complex, leads to a strong inhibition of endocytosis, vesicle accumulation, enlargement of the flagellar pocket ("big eye" phenotype), and dramatic effect on cell growth. Unexpectedly, other functions described for Vps41 in mammalian cells and yeasts, such as delivery of proteins to lysosomes, and lysosome-related organelles (acidocalcisomes) were unaffected, indicating that in trypanosomes post-Golgi trafficking is distinct from that of mammalian cells and yeasts. The essentiality of TbVps41 suggests that it is a potential drug target.
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Affiliation(s)
| | | | - Beejan Asady
- Center for Tropical and Emerging Global Diseases, Athens, GA, USA
| | - Guozhong Huang
- Center for Tropical and Emerging Global Diseases, Athens, GA, USA
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases, Athens, GA, USA.,Department of Cellular Biology, University of Georgia, Athens, GA, USA
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5
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Cruz-Saavedra L, Vallejo GA, Guhl F, Messenger LA, Ramírez JD. Transcriptional remodeling during metacyclogenesis in Trypanosoma cruzi I. Virulence 2021; 11:969-980. [PMID: 32715914 PMCID: PMC7549971 DOI: 10.1080/21505594.2020.1797274] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Metacyclogenesis is one of the most important processes in the life cycle of Trypanosoma cruzi. In this stage, noninfective epimastigotes become infective metacyclic trypomastigotes. However, the transcriptomic changes that occur during this transformation remain uncertain. Illumina RNA-sequencing of epimastigotes and metacyclic trypomastigotes belonging to T. cruzi DTU I was undertaken. Sequencing reads were aligned and mapped against the reference genome, differentially expressed genes between the two life cycle stages were identified, and metabolic pathways were reconstructed. Gene expression differed significantly between epimastigotes and metacyclic trypomastigotes. The cellular pathways that were mostly downregulated during metacyclogenesis involved glucose energy metabolism (glycolysis, pyruvate metabolism, the Krebs cycle, and oxidative phosphorylation), amino acid metabolism, and DNA replication. By contrast, the processes where an increase in gene expression was observed included those related to autophagy (particularly Atg7 and Atg8 transcripts), corroborating its importance during metacyclogenesis, endocytosis, by an increase in the expression of the AP-2 complex subunit alpha, protein processing in the endoplasmic reticulum and meiosis. Study findings indicate that in T. cruzi metacyclic trypomastigotes, metabolic processes are decreased, and expression of genes involved in specific cell cycle processes is increased to facilitate transformation to this infective stage.
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Affiliation(s)
- Lissa Cruz-Saavedra
- Grupo de Investigaciones Microbiológicas-UR (GIMUR), Departamento de Biología, Facultad de Ciencias Naturales, Universidad del Rosario , Bogotá, Colombia
| | - Gustavo A Vallejo
- Laboratorio de Investigaciones en Parasitología Tropical, Facultad de Ciencias, Universidad del Tolima , Ibagué, Colombia
| | - Felipe Guhl
- Centro de Investigaciones en Microbiología y Parasitología Tropical (CIMPAT), Facultad de Ciencias, Universidad de Los Andes , Bogotá, Colombia
| | | | - Juan David Ramírez
- Grupo de Investigaciones Microbiológicas-UR (GIMUR), Departamento de Biología, Facultad de Ciencias Naturales, Universidad del Rosario , Bogotá, Colombia
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6
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Kohlschmidt N, Elbracht M, Czech A, Häusler M, Phan V, Töpf A, Huang KT, Bartok A, Eggermann K, Zippel S, Eggermann T, Freier E, Groß C, Lochmüller H, Horvath R, Hajnóczky G, Weis J, Roos A. Molecular pathophysiology of human MICU1 deficiency. Neuropathol Appl Neurobiol 2021; 47:840-855. [PMID: 33428302 DOI: 10.1111/nan.12694] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 09/07/2020] [Accepted: 09/14/2020] [Indexed: 12/20/2022]
Abstract
AIMS MICU1 encodes the gatekeeper of the mitochondrial Ca2+ uniporter, MICU1 and biallelic loss-of-function mutations cause a complex, neuromuscular disorder in children. Although the role of the protein is well understood, the precise molecular pathophysiology leading to this neuropaediatric phenotype has not been fully elucidated. Here we aimed to obtain novel insights into MICU1 pathophysiology. METHODS Molecular genetic studies along with proteomic profiling, electron-, light- and Coherent anti-Stokes Raman scattering microscopy and immuno-based studies of protein abundances and Ca2+ transport studies were employed to examine the pathophysiology of MICU1 deficiency in humans. RESULTS We describe two patients carrying MICU1 mutations, two nonsense (c.52C>T; p.(Arg18*) and c.553C>T; p.(Arg185*)) and an intragenic exon 2-deletion presenting with ataxia, developmental delay and early onset myopathy, clinodactyly, attention deficits, insomnia and impaired cognitive pain perception. Muscle biopsies revealed signs of dystrophy and neurogenic atrophy, severe mitochondrial perturbations, altered Golgi structure, vacuoles and altered lipid homeostasis. Comparative mitochondrial Ca2+ transport and proteomic studies on lymphoblastoid cells revealed that the [Ca2+ ] threshold and the cooperative activation of mitochondrial Ca2+ uptake were lost in MICU1-deficient cells and that 39 proteins were altered in abundance. Several of those proteins are linked to mitochondrial dysfunction and/or perturbed Ca2+ homeostasis, also impacting on regular cytoskeleton (affecting Spectrin) and Golgi architecture, as well as cellular survival mechanisms. CONCLUSIONS Our findings (i) link dysregulation of mitochondrial Ca2+ uptake with muscle pathology (including perturbed lipid homeostasis and ER-Golgi morphology), (ii) support the concept of a functional interplay of ER-Golgi and mitochondria in lipid homeostasis and (iii) reveal the vulnerability of the cellular proteome as part of the MICU1-related pathophysiology.
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Affiliation(s)
| | - Miriam Elbracht
- Institute of Human Genetics, RWTH Aachen University Hospital, Aachen, Germany
| | - Artur Czech
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Dortmund, Germany
| | - Martin Häusler
- Division of Neuropediatrics and Social Pediatrics, Department of Pediatrics, RWTH Aachen University Hospital, Aachen, Germany
| | - Vietxuan Phan
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Dortmund, Germany
| | - Ana Töpf
- Institute of Genetic Medicine, International Centre for Life, Central Parkway, Newcastle upon Tyne, UK
| | - Kai-Ting Huang
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Adam Bartok
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Katja Eggermann
- Institute of Human Genetics, RWTH Aachen University Hospital, Aachen, Germany
| | | | - Thomas Eggermann
- Institute of Human Genetics, RWTH Aachen University Hospital, Aachen, Germany
| | - Erik Freier
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Dortmund, Germany
| | - Claudia Groß
- Institute of Clinical Genetics and Tumour Genetics, Bonn, Germany
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Centro Nacional de Análisis Genómico, Center for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Rita Horvath
- Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany
| | - Andreas Roos
- Department of Neuropediatrics, Centre for Neuromuscular Disorders in Children, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
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7
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Sanz-Luque E, Bhaya D, Grossman AR. Polyphosphate: A Multifunctional Metabolite in Cyanobacteria and Algae. FRONTIERS IN PLANT SCIENCE 2020; 11:938. [PMID: 32670331 PMCID: PMC7332688 DOI: 10.3389/fpls.2020.00938] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/09/2020] [Indexed: 05/19/2023]
Abstract
Polyphosphate (polyP), a polymer of orthophosphate (PO4 3-) of varying lengths, has been identified in all kingdoms of life. It can serve as a source of chemical bond energy (phosphoanhydride bond) that may have been used by biological systems prior to the evolution of ATP. Intracellular polyP is mainly stored as granules in specific vacuoles called acidocalcisomes, and its synthesis and accumulation appear to impact a myriad of cellular functions. It serves as a reservoir for inorganic PO4 3- and an energy source for fueling cellular metabolism, participates in maintaining adenylate and metal cation homeostasis, functions as a scaffold for sequestering cations, exhibits chaperone function, covalently binds to proteins to modify their activity, and enables normal acclimation of cells to stress conditions. PolyP also appears to have a role in symbiotic and parasitic associations, and in higher eukaryotes, low polyP levels seem to impact cancerous proliferation, apoptosis, procoagulant and proinflammatory responses and cause defects in TOR signaling. In this review, we discuss the metabolism, storage, and function of polyP in photosynthetic microbes, which mostly includes research on green algae and cyanobacteria. We focus on factors that impact polyP synthesis, specific enzymes required for its synthesis and degradation, sequestration of polyP in acidocalcisomes, its role in cellular energetics, acclimation processes, and metal homeostasis, and then transition to its potential applications for bioremediation and medical purposes.
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Affiliation(s)
- Emanuel Sanz-Luque
- Department of Plant Biology, The Carnegie Institution for Science, Stanford, CA, United States
- Department of Biochemistry and Molecular Biology, University of Cordoba, Cordoba, Spain
| | - Devaki Bhaya
- Department of Plant Biology, The Carnegie Institution for Science, Stanford, CA, United States
| | - Arthur R. Grossman
- Department of Plant Biology, The Carnegie Institution for Science, Stanford, CA, United States
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8
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McCarthy L, Bentley‐DeSousa A, Denoncourt A, Tseng Y, Gabriel M, Downey M. Proteins required for vacuolar function are targets of lysine polyphosphorylation in yeast. FEBS Lett 2019; 594:21-30. [DOI: 10.1002/1873-3468.13588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/22/2019] [Accepted: 08/23/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Liam McCarthy
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Amanda Bentley‐DeSousa
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Alix Denoncourt
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Yi‐Chieh Tseng
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Matthew Gabriel
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Michael Downey
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
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9
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Goodenough U, Heiss AA, Roth R, Rusch J, Lee JH. Acidocalcisomes: Ultrastructure, Biogenesis, and Distribution in Microbial Eukaryotes. Protist 2019; 170:287-313. [DOI: 10.1016/j.protis.2019.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 04/26/2019] [Accepted: 05/01/2019] [Indexed: 12/19/2022]
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10
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Kohl K, Zangger H, Rossi M, Isorce N, Lye LF, Owens KL, Beverley SM, Mayer A, Fasel N. Importance of polyphosphate in the Leishmania life cycle. MICROBIAL CELL 2018; 5:371-384. [PMID: 30175107 PMCID: PMC6116282 DOI: 10.15698/mic2018.08.642] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Protozoan parasites contain negatively charged polymers of a few up to several hundreds of phosphate residues. In other organisms, these poly-phosphate (polyP) chains serve as an energy source and phosphate reservoir, and have been implicated in adaptation to stress and virulence of pathogenic organisms. In this study, we confirmed first that the polyP polymerase vacuolar transporter chaperone 4 (VTC4) is responsible for polyP synthesis in Leishmania parasites. During Leishmaniain vitro culture, polyP is accumulated in logarithmic growth phase and subsequently consumed once stationary phase is reached. However, polyP is not essential since VTC4-deficient (vtc4-) Leishmania proliferated normally in culture and differentiated into infective metacyclic parasites and into intracellular and axenic amastigotes. In in vivo mouse infections, L. majorVTC4 knockout showed a delay in lesion formation but ultimately gave rise to strong pathology, although we were unable to restore virulence by complementation to confirm this phenotype. Knockdown of VTC4 did not alter the course of L. guyanensis infections in mice, suggesting that polyP was not required for infection, or that very low levels of it suffice for lesion development. At higher temperatures, Leishmania promastigotes highly consumed polyP, and both knockdown or deletion of VTC4 diminished parasite survival. Thus, although polyP was not essential in the life cycle of the parasite, our data suggests a role for polyP in increasing parasite survival at higher temperatures, a situation faced by the parasite when transmitted to humans.
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Affiliation(s)
- Kid Kohl
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Haroun Zangger
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Matteo Rossi
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Nathalie Isorce
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Lon-Fye Lye
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Katherine L Owens
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Stephen M Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Andreas Mayer
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Nicolas Fasel
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
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11
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Jardim A, Hardie DB, Boitz J, Borchers CH. Proteomic Profiling of Leishmania donovani Promastigote Subcellular Organelles. J Proteome Res 2018; 17:1194-1215. [PMID: 29332401 DOI: 10.1021/acs.jproteome.7b00817] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To facilitate a greater understanding of the biological processes in the medically important Leishmania donovani parasite, a combination of differential and density-gradient ultracentrifugation techniques were used to achieve a comprehensive subcellular fractionation of the promastigote stage. An in-depth label-free proteomic LC-MS/MS analysis of the density gradients resulted in the identification of ∼50% of the Leishmania proteome (3883 proteins detected), which included ∼645 integral membrane proteins and 1737 uncharacterized proteins. Clustering and subcellular localization of proteins was based on a subset of training Leishmania proteins with known subcellular localizations that had been determined using biochemical, confocal microscopy, or immunoelectron microscopy approaches. This subcellular map will be a valuable resource that will help dissect the cell biology and metabolic processes associated with specific organelles of Leishmania and related kinetoplastids.
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Affiliation(s)
- Armando Jardim
- Institute of Parasitology, Macdonald Campus, McGill University , 21111 Lakeshore Road, Saine-Anne-de-Bellevue, Québec H9X 3V9, Canada
| | - Darryl B Hardie
- University of Victoria -Genome British Columbia Proteomics Centre , #3101-4464 Markham Street, Vancouver Island Technology Park, Victoria, British Columbia V8Z7X8, Canada
| | - Jan Boitz
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University , Portland, Oregon 97239, United States
| | - Christoph H Borchers
- University of Victoria -Genome British Columbia Proteomics Centre , #3101-4464 Markham Street, Vancouver Island Technology Park, Victoria, British Columbia V8Z7X8, Canada.,Department of Biochemistry and Biophysics, University of North Carolina , 120 Mason Farm Road, Campus Box 7260 Third Floor, Genetic Medicine Building, Chapel Hill, North Carolina 27599, United States.,Department of Biochemistry and Microbiology, University of Victoria , Petch Building, Room 270d, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada.,Gerald Bronfman Department of Oncology, Jewish General Hospital, McGill University , 3755 Côte Ste-Catherine Road, Montreal, Quebec H3T 1E2, Canada.,Proteomics Centre, Segal Cancer Centre, Lady Davis Institute, Jewish General Hospital, McGill University , 3755 Côte Ste-Catherine Road, Montreal, Quebec H3T 1E2, Canada
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12
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Magnesium uptake by connecting fluid-phase endocytosis to an intracellular inorganic cation filter. Nat Commun 2017; 8:1879. [PMID: 29192218 PMCID: PMC5709425 DOI: 10.1038/s41467-017-01930-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 10/24/2017] [Indexed: 12/03/2022] Open
Abstract
Cells acquire free metals through plasma membrane transporters. But, in natural settings, sequestering agents often render metals inaccessible to transporters, limiting metal bioavailability. Here we identify a pathway for metal acquisition, allowing cells to cope with this situation. Under limited bioavailability of Mg2+, yeast cells upregulate fluid-phase endocytosis and transfer solutes from the environment into their vacuole, an acidocalcisome-like compartment loaded with highly concentrated polyphosphate. We propose that this anionic inorganic polymer, which is an avid chelator of Mg2+, serves as an immobilized cation filter that accumulates Mg2+ inside these organelles. It thus allows the vacuolar exporter Mnr2 to efficiently transfer Mg2+ into the cytosol. Leishmania parasites also employ acidocalcisomal polyphosphate to multiply in their Mg2+-limited habitat, the phagolysosomes of inflammatory macrophages. This suggests that the pathway for metal uptake via endocytosis, acidocalcisomal polyphosphates and export into the cytosol, which we term EAPEC, is conserved. Metal bioavailability is frequently limited by sequestering agents which makes them inaccessible to cells. Here the authors show that cells can increase Mg2+ uptake via fluid phase endocytosis and accumulate this metal in their vacuole loaded with polyphosphate, and later can be exported to the cytosol.
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13
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Biswas A, Bhattacharya A, Vij A, Das PK. Role of leishmanial acidocalcisomal pyrophosphatase in the cAMP homeostasis in phagolysosome conditions required for intra-macrophage survival. Int J Biochem Cell Biol 2017; 86:1-13. [PMID: 28268199 DOI: 10.1016/j.biocel.2017.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 03/01/2017] [Accepted: 03/02/2017] [Indexed: 02/01/2023]
Abstract
Exposure of Leishmania donovani to macrophage phagolysosome conditions (PC) (37°C and pH 5.5) led to increased intracellular cAMP and cAMP-mediated responses, which help in intra-macrophage survival pre-requisite for infectivity. In the absence of typical orthologs for G-proteins and G-protein coupled receptors, we sought to study the precise mechanisms for positive modulation of cAMP production during exposure to PC. Amongst two promastigote-stage specific membrane bound receptor adenylate cyclases (LdRAC-A and LdRAC-B), LdRAC-A appeared to function as a major cAMP generator following PC exposure. Pyrophosphate (PPi), an energy storage compound as well as a by-product of cAMP biosynthesis by adenylate cyclise, was found to be decreased following PC exposure. This may be due to microtubule and microfilament-driven translocation of acidocalcisomes near plasma membrane vicinity with concomitant increase of acidocalcisome membrane pyrophosphatase (LdV-H+PPase) and acidocalcisomal soluble pyrophosphatase (LdVSP1). Episomal over-expression and conditional silencing demonstrated regulatory role of V-H+PPase on cAMP trigger and consequent induction of resistance to macrophage-derived pro-oxidants and parasite killing. Furthermore, immunofluorescence analysis revealed possible co-localization of LdV-H+PPase and LdRAC-A during PC exposure. Collectively, these results suggest that translocation of acidocalcisome in membrane vicinity functions as a trigger for LdRAC-A-driven cAMP generation through depletion of PPi pool by LdV-H+PPase.
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Affiliation(s)
- Arunima Biswas
- Department of Zoology, University of Kalyani, Kalyani, Nadia 741325, India
| | - Arijit Bhattacharya
- Centre de Rechercheen Infectiologie, Centre de Recherche du CHU de Québec, University of Laval, Quebec City, Quebec, Canada
| | - Amit Vij
- CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata 700032, India
| | - Pijush K Das
- CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata 700032, India.
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14
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Abstract
Inorganic polyphosphate (polyP) accumulates in acidocalcisomes, acidic calcium stores that have been found from bacteria to human cells. Proton pumps, such as the vacuolar proton pyrophosphatase (V-H(+)-PPase or VP1), the vacuolar proton ATPase (V-H(+)-ATPase) or both, maintain their acidity. A vacuolar transporter chaperone (VTC) complex is involved in the synthesis and translocation of polyP to these organelles in several eukaryotes, such as yeast, trypanosomatids, Apicomplexan and algae. Studies in trypanosomatids have revealed the role of polyP and acidocalcisomes in osmoregulation and calcium signalling.
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15
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Deciphering the relationship among phosphate dynamics, electron-dense body and lipid accumulation in the green alga Parachlorella kessleri. Sci Rep 2016; 6:25731. [PMID: 27180903 PMCID: PMC4867602 DOI: 10.1038/srep25731] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 04/18/2016] [Indexed: 01/08/2023] Open
Abstract
Phosphorus is an essential element for life on earth and is also important for modern agriculture, which is dependent on inorganic fertilizers from phosphate rock. Polyphosphate is a biological polymer of phosphate residues, which is accumulated in organisms during the biological wastewater treatment process to enhance biological phosphorus removal. Here, we investigated the relationship between polyphosphate accumulation and electron-dense bodies in the green alga Parachlorella kessleri. Under sulfur-depleted conditions, in which some symporter genes were upregulated, while others were downregulated, total phosphate accumulation increased in the early stage of culture compared to that under sulfur-replete conditions. The P signal was detected only in dense bodies by energy dispersive X-ray analysis. Transmission electron microscopy revealed marked ultrastructural variations in dense bodies with and without polyphosphate. Our findings suggest that the dense body is a site of polyphosphate accumulation, and P. kessleri has potential as a phosphate-accumulating organism.
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16
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Docampo R, Huang G. Acidocalcisomes of eukaryotes. Curr Opin Cell Biol 2016; 41:66-72. [PMID: 27125677 DOI: 10.1016/j.ceb.2016.04.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/30/2016] [Accepted: 04/07/2016] [Indexed: 01/01/2023]
Abstract
Acidocalcisomes are organelles rich in polyphosphate and cations and acidified by proton pumps. Although they have also been described in prokaryotes they have been better characterized in unicellular and multicellular eukaryotes. Eukaryotic acidocalcisomes belong to the group of lysosome-related organelles. They have a variety of functions, from the storage of cations and phosphorus to calcium signaling, autophagy, osmoregulation, blood coagulation, and inflammation. Acidocalcisomes of several unicellular eukaryotes possess a variety of transporters, channels and pumps implying a large energetic requirement for their maintenance and suggesting other important functions waiting to be discovered.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
| | - Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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17
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Docampo R. The origin and evolution of the acidocalcisome and its interactions with other organelles. Mol Biochem Parasitol 2015; 209:3-9. [PMID: 26523947 DOI: 10.1016/j.molbiopara.2015.10.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 10/04/2015] [Accepted: 10/19/2015] [Indexed: 01/11/2023]
Abstract
Acidocalcisomes are acidic calcium stores that have been found from bacteria to human cells. They are rich in phosphorus compounds in the form of orthophosphate (Pi), pyrophosphate (PPi), and polyphosphate (polyP) and their acidity is maintained by proton pumps such as the vacuolar proton pyrophosphatase (V-H+-PPase, or VP1), the vacuolar proton ATPase (V-H+-ATPase), or both. Recent studies in trypanosomatids and in other species have revealed their role in phosphate metabolism, and cation and water homeostasis, as suggested by the presence of novel pumps, transporters, and channels. An important role in autophagy has also been described. The study of the biogenesis of acidocalcisomes as well as of the interactions of these lysosome-related organelles with other organelles have uncovered important roles in calcium signaling and osmoregulation. Significantly, despite conservation of acidocalcisomes across all of cellular life, there is evidence for intimate integration of these organelles with eukaryotic cellular functions, and which are directly relevant to parasites.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Global Emerging Diseases and Department of Cellular Biology, University of Georgia, Athens 30602, USA; Departamento de Patología Clínica, Universidade Estadual de Campinas, São Paulo 13083-877, Brazil.
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18
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Abstract
Lysosomes play important roles in autophagy, not only in autophagosome degradation, but also in autophagy initiation. In Trypanosoma brucei, an early divergent protozoan parasite, we discovered a previously unappreciated function of the acidocalcisome, a lysosome-related organelle characterized by acidic pH and large content of Ca(2+) and polyphosphates, in autophagy regulation. Starvation- and chemical-induced autophagy is accompanied with acidocalcisome acidification, and blocking the acidification completely inhibits autophagosome formation. Blocking acidocalcisome biogenesis by depleting the adaptor protein-3 complex, which does not affect lysosome biogenesis or function, also inhibits autophagy. Overall, our results support the role of the acidocalcisome, a conserved organelle from bacteria to human, as a relevant regulator in autophagy.
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Key Words
- AO, acridine orange
- AP-3, adaptor protein-3
- ATG, autophagy-related
- BODIPY-CQ, BODIPY-chloroquine
- BafA1, bafilomycin A1
- CQ, chloroquine
- DAPI, 4′, 6-diamidino-2-phenylindole
- MTORC1, mechanistic target of rapamycin complex 1
- PPi, pyrophosphate
- PtdIns3K, phosphatidylinositol 3-kinase
- PtdIns3P, phosphatidylinositol 3-phosphate
- RNAi, RNA interference
- T. brucei, Trypanosoma brucei
- TOR, target of rapamycin
- TbVMA1, the subunit A of V-H+-ATPase in Trypanosoma brucei
- TbVP1, vacuolar pyrophosphatase in Trypanosoma brucei
- TbVPH1, the α, subunit of V-H+-ATPase in Trypanosoma brucei
- Tbβ3, the β3 subunit of adaptor protein-3 complex in Trypanosoma brucei
- Tbδ, the δ, subunit of adaptor protein-3 complex in Trypanosoma brucei
- Trypanosoma brucei
- V-H+-ATPase, vacuolar-type H+-ATPase
- V-PPase, vacuolar pyrophophatase
- acidity
- acidocalcisome
- autophagy
- coumarin-CQ, coumarin-chloroquine
- lysosome-related organelle
- polyP, polyphosphate
- protozoan parasite
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Affiliation(s)
- Feng-Jun Li
- a Department of Biological Sciences ; National University of Singapore ; Singapore
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19
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Von Bülow J, Beitz E. Number and regulation of protozoan aquaporins reflect environmental complexity. THE BIOLOGICAL BULLETIN 2015; 229:38-46. [PMID: 26338868 DOI: 10.1086/bblv229n1p38] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Protozoa are a diverse group of unicellular eukaryotes. Evidence has accumulated that protozoan aquaporin water and solute channels (AQP) contribute to adaptation in changing environments. Intracellular protozoan parasites live a well-sheltered life. Plasmodium spp. express a single AQP, Toxoplasma gondii two, while Trypanosoma cruzi and Leishamnia spp. encode up to five AQPs. Their AQPs are thought to import metabolic precursors and simultaneously to dispose of waste and to help parasites survive osmotic stress during transmission to and from the insect vector or during kidney passages. Trypanosoma brucei is a protozoan parasite that swims freely in the human blood. Expression and intracellular localization of the three T. brucei AQPs depend on the stage of differentiation during the life cycle, suggesting distinct roles in energy generation, metabolism, and cell motility. Free-living amoebae are in direct contact with the environment, encountering severe and sudden changes in the availability of nutrition, and in the osmotic conditions due to rainfall or drought. Amoeba proteus expresses a single AQP that is present in the contractile vacuole complex required for osmoregulation, whereas Dictyostelium discoideum expresses four AQPs, of which two are present in the single-celled amoeboidal stage and two more in the later multicellular stages preceding spore formation. The number and regulation of protozoan aquaporins may reflect environmental complexity. We highlight the gated AqpB from D. discoideum as an example of how life in the wild is challenged by a complex AQP structure-function relationship.
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Affiliation(s)
- Julia Von Bülow
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Gutenbergstrasse 76, 24118 Kiel, Germany
| | - Eric Beitz
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Gutenbergstrasse 76, 24118 Kiel, Germany
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20
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Vacuolar ATPase depletion affects mitochondrial ATPase function, kinetoplast dependency, and drug sensitivity in trypanosomes. Proc Natl Acad Sci U S A 2015; 112:9112-7. [PMID: 26150481 DOI: 10.1073/pnas.1505411112] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Kinetoplastid parasites cause lethal diseases in humans and animals. The kinetoplast itself contains the mitochondrial genome, comprising a huge, complex DNA network that is also an important drug target. Isometamidium, for example, is a key veterinary drug that accumulates in the kinetoplast in African trypanosomes. Kinetoplast independence and isometamidium resistance are observed where certain mutations in the F1-γ-subunit of the two-sector F1Fo-ATP synthase allow for Fo-independent generation of a mitochondrial membrane potential. To further explore kinetoplast biology and drug resistance, we screened a genome-scale RNA interference library in African trypanosomes for isometamidium resistance mechanisms. Our screen identified 14 V-ATPase subunits and all 4 adaptin-3 subunits, implicating acidic compartment defects in resistance; V-ATPase acidifies lysosomes and related organelles, whereas adaptin-3 is responsible for trafficking among these organelles. Independent strains with depleted V-ATPase or adaptin-3 subunits were isometamidium resistant, and chemical inhibition of the V-ATPase phenocopied this effect. While drug accumulation in the kinetoplast continued after V-ATPase subunit depletion, acriflavine-induced kinetoplast loss was specifically tolerated in these cells and in cells depleted for adaptin-3 or endoplasmic reticulum membrane complex subunits, also identified in our screen. Consistent with kinetoplast dispensability, V-ATPase defective cells were oligomycin resistant, suggesting ATP synthase uncoupling and bypass of the normal Fo-A6-subunit requirement; this subunit is the only kinetoplast-encoded product ultimately required for viability in bloodstream-form trypanosomes. Thus, we describe 30 genes and 3 protein complexes associated with kinetoplast-dependent growth. Mutations affecting these genes could explain natural cases of dyskinetoplasty and multidrug resistance. Our results also reveal potentially conserved communication between the compartmentalized two-sector rotary ATPases.
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21
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Niyogi S, Jimenez V, Girard-Dias W, de Souza W, Miranda K, Docampo R. Rab32 is essential for maintaining functional acidocalcisomes, and for growth and infectivity of Trypanosoma cruzi. J Cell Sci 2015; 128:2363-73. [PMID: 25964650 DOI: 10.1242/jcs.169466] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 04/30/2015] [Indexed: 02/01/2023] Open
Abstract
The contractile vacuole complex (CVC) of Trypanosoma cruzi, the etiologic agent of Chagas disease, collects and expels excess water as a mechanism of regulatory volume decrease after hyposmotic stress; it also has a role in cell shrinking after hyperosmotic stress. Here, we report that, in addition to its role in osmoregulation, the CVC of T. cruzi has a role in the biogenesis of acidocalcisomes. Expression of dominant-negative mutants of the CVC-located small GTPase Rab32 (TcCLB.506289.80) results in lower numbers of less-electron-dense acidocalcisomes, lower content of polyphosphate, lower capacity for acidocalcisome acidification and Ca(2+) uptake that is driven by the vacuolar proton pyrophosphatase and the Ca(2+)-ATPase, respectively, as well as less-infective parasites, revealing the role of this organelle in parasite infectivity. By using fluorescence, electron microscopy and electron tomography analyses, we provide further evidence of the active contact of acidocalcisomes with the CVC, indicating an active exchange of proteins between the two organelles.
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Affiliation(s)
- Sayantanee Niyogi
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Veronica Jimenez
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Wendell Girard-Dias
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho and Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens - Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Wanderley de Souza
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho and Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens - Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil Diretoria de Metrologia Aplicada a Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Xerém, Rio de Janeiro 25250-020, Brazil
| | - Kildare Miranda
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho and Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens - Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil Diretoria de Metrologia Aplicada a Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Xerém, Rio de Janeiro 25250-020, Brazil
| | - Roberto Docampo
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
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22
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Huang G, Docampo R. Proteomic analysis of acidocalcisomes of Trypanosoma brucei uncovers their role in phosphate metabolism, cation homeostasis, and calcium signaling. Commun Integr Biol 2015; 8:e1017174. [PMID: 26480268 PMCID: PMC4594416 DOI: 10.1080/19420889.2015.1017174] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 01/21/2015] [Accepted: 01/22/2015] [Indexed: 12/23/2022] Open
Abstract
Trypanosomabrucei, the causative agent of African trypanosomiasis, is a unicellular parasite that possesses lysosome-related organelles known as acidocalcisomes. These organelles have been found from bacteria to human cells, and are characterized by their acidic nature and high calcium and polyphosphate (polyP) content. Our proteomic analysis of acidocalcisomes of T. brucei procyclic stages, together with in situ epitope-tagging and immunofluorescence assays with specific antibodies against selected proteins, established the presence of 2 H+ pumps, a vacuolar H+-ATPase and a vacuolar H+-pyrophosphatase, that acidify the organelles as well as of a number of transporters and channels involved in phosphate metabolism, cation uptake and calcium signaling. Together with recent work in other organisms, these results provide direct evidence that acidocalcisomes are especially adapted to accumulate polyP bound to cations and for calcium signaling.
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Affiliation(s)
- Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology; University of Georgia ; Athens, Georgia
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology; University of Georgia ; Athens, Georgia
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23
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Lourido S, Moreno SNJ. The calcium signaling toolkit of the Apicomplexan parasites Toxoplasma gondii and Plasmodium spp. Cell Calcium 2014; 57:186-93. [PMID: 25605521 DOI: 10.1016/j.ceca.2014.12.010] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 12/15/2014] [Indexed: 12/21/2022]
Abstract
Apicomplexan parasites have complex life cycles, frequently split between different hosts and reliant on rapid responses as the parasites react to changing environmental conditions. Calcium ion (Ca(2+)) signaling is consequently essential for the cellular and developmental changes that support Apicomplexan parasitism. Apicomplexan genomes reveal a rich repertoire of genes involved in calcium signaling, although many of the genes responsible for observed physiological changes remain unknown. There is evidence, for example, for the presence of a nifedipine-sensitive calcium entry mechanism in Toxoplasma, but the molecular components involved in Ca(2+) entry in both Toxoplasma and Plasmodium, have not been identified. The major calcium stores are the endoplasmic reticulum (ER), the acidocalcisomes, and the plant-like vacuole in Toxoplasma, or the food vacuole in Plasmodium spp. Pharmacological evidence suggests that Ca(2+) release from intracellular stores may be mediated by inositol 1,4,5-trisphosphate (IP3) or cyclic ADP ribose (cADPR) although there is no molecular evidence for the presence of receptors for these second messengers in the parasites. Several Ca(2+)-ATPases are present in Apicomplexans and a putative mitochondrial Ca(2+)/H(+) exchanger has been identified. Apicomplexan genomes contain numerous genes encoding Ca(2+)-binding proteins, with the notable expansion of calcium-dependent protein kinases (CDPKs), whose study has revealed roles in gliding motility, microneme secretion, host cell invasion and egress, and parasite differentiation. Microneme secretion has also been shown to depend on the C2 domain containing protein DOC2 in both Plasmodium spp. and Toxoplasma, providing further evidence for the complex transduction of Ca(2+) signals in these organisms. The characterization of these pathways could lead to the discovery of novel drug targets and to a better understanding of the role of Ca(2+) in these parasites.
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Affiliation(s)
- Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
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24
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Huang G, Ulrich PN, Storey M, Johnson D, Tischer J, Tovar JA, Moreno SNJ, Orlando R, Docampo R. Proteomic analysis of the acidocalcisome, an organelle conserved from bacteria to human cells. PLoS Pathog 2014; 10:e1004555. [PMID: 25503798 PMCID: PMC4263762 DOI: 10.1371/journal.ppat.1004555] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 11/05/2014] [Indexed: 01/12/2023] Open
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.
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Affiliation(s)
- Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Paul N Ulrich
- Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Melissa Storey
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Darryl Johnson
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Julie Tischer
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Javier A Tovar
- Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Ron Orlando
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
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25
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Hong-Hermesdorf A, Miethke M, Gallaher SD, Kropat J, Dodani SC, Chan J, Barupala D, Domaille DW, Shirasaki DI, Loo JA, Weber PK, Pett-Ridge J, Stemmler TL, Chang CJ, Merchant SS. Subcellular metal imaging identifies dynamic sites of Cu accumulation in Chlamydomonas. Nat Chem Biol 2014; 10:1034-42. [PMID: 25344811 PMCID: PMC4232477 DOI: 10.1038/nchembio.1662] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 09/05/2014] [Indexed: 12/03/2022]
Abstract
We identified a Cu-accumulating structure with a dynamic role in intracellular Cu homeostasis. During Zn limitation, Chlamydomonas reinhardtii hyperaccumulates Cu, a process dependent on the nutritional Cu sensor CRR1, but it is functionally Cu deficient. Visualization of intracellular Cu revealed major Cu accumulation sites coincident with electron-dense structures that stained positive for low pH and polyphosphate, suggesting that they are lysosome-related organelles. Nano-secondary ion MS showed colocalization of Ca and Cu, and X-ray absorption spectroscopy was consistent with Cu(+) accumulation in an ordered structure. Zn resupply restored Cu homeostasis concomitant with reduced abundance of these structures. Cu isotope labeling demonstrated that sequestered Cu(+) became bioavailable for the synthesis of plastocyanin, and transcriptome profiling indicated that mobilized Cu became visible to CRR1. Cu trafficking to intracellular accumulation sites may be a strategy for preventing protein mismetallation during Zn deficiency and enabling efficient cuproprotein metallation or remetallation upon Zn resupply.
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Affiliation(s)
- Anne Hong-Hermesdorf
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Marcus Miethke
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Sean D Gallaher
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Janette Kropat
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Sheel C Dodani
- Department of Chemistry and Howard Hughes Medical Institute, University of California, Berkeley, USA
| | - Jefferson Chan
- Department of Chemistry and Howard Hughes Medical Institute, University of California, Berkeley, USA
| | - Dulmini Barupala
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, USA
| | - Dylan W Domaille
- Department of Chemistry and Howard Hughes Medical Institute, University of California, Berkeley, USA
| | - Dyna I Shirasaki
- Department of Biological Chemistry, University of California, Los Angeles, USA
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA.Institute for Genomics and Proteomics, University of California, Los Angeles, USA.Department of Biological Chemistry, University of California, Los Angeles, USA
| | - Peter K Weber
- Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, USA
| | - Jennifer Pett-Ridge
- Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, USA
| | - Timothy L Stemmler
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, USA
| | - Christopher J Chang
- Department of Chemistry and Howard Hughes Medical Institute, University of California, Berkeley, USA
| | - Sabeeha S Merchant
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA.Institute for Genomics and Proteomics, University of California, Los Angeles, USA
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26
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Abstract
Metal ion assimilation is essential for all forms of life. However, organisms must properly control the availability of these nutrients within the cell to avoid inactivating proteins by mismetallation. To safeguard against an imbalance between supply and demand in eukaryotes, intracellular compartments contain metal transporters that load and unload metals. Although the vacuoles of Saccharomyces cerevisiae and Arabidopsis thaliana are well established locales for the storage of copper, zinc, iron, and manganese, related compartments are emerging as important mediators of metal homeostasis. Here we describe these compartments and review their metal transporter complement.
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Affiliation(s)
| | - Sabeeha S Merchant
- From the Department of Chemistry and Biochemistry and the Institute for Genomics and Proteomics, UCLA, Los Angeles, California 90095
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27
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Huang G, Vercesi AE, Docampo R. Essential regulation of cell bioenergetics in Trypanosoma brucei by the mitochondrial calcium uniporter. Nat Commun 2014; 4:2865. [PMID: 24305511 PMCID: PMC3868461 DOI: 10.1038/ncomms3865] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 11/04/2013] [Indexed: 01/07/2023] Open
Abstract
Mechanisms of regulation of mitochondrial metabolism in trypanosomes are not completely understood. Here we present evidence that the Trypanosoma brucei mitochondrial calcium uniporter (TbMCU) is essential for regulation of mitochondrial bioenergetics, autophagy, and cell death, even in the bloodstream forms that are devoid of a functional respiratory chain and oxidative phosphorylation. Localization studies reveal its co-localization with MitoTracker staining. TbMCU overexpression increases mitochondrial Ca2+ accumulation in intact and permeabilized trypanosomes, generates excessive mitochondrial reactive oxygen species (ROS), and sensitizes them to apoptotic stimuli. Ablation of TbMCU in RNAi or conditional knockout trypanosomes reduces mitochondrial Ca2+ uptake without affecting their membrane potential, increases the AMP/ATP ratio, stimulates autophagosome formation, and produces marked defects in growth in vitro and infectivity in mice, revealing its essentiality in these parasites. The requirement of TbMCU for proline and pyruvate metabolism in procyclic and bloodstream forms, respectively, reveals its role in regulation of mitochondrial bioenergetics.
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Affiliation(s)
- Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602, USA
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28
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Parasite aquaporins: Current developments in drug facilitation and resistance. Biochim Biophys Acta Gen Subj 2014; 1840:1566-73. [DOI: 10.1016/j.bbagen.2013.10.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 10/02/2013] [Accepted: 10/06/2013] [Indexed: 01/15/2023]
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29
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Ulrich PN, Lander N, Kurup SP, Reiss L, Brewer J, Soares Medeiros LC, Miranda K, Docampo R. The acidocalcisome vacuolar transporter chaperone 4 catalyzes the synthesis of polyphosphate in insect-stages of Trypanosoma brucei and T. cruzi. J Eukaryot Microbiol 2014; 61:155-65. [PMID: 24386955 DOI: 10.1111/jeu.12093] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 11/06/2013] [Accepted: 11/06/2013] [Indexed: 11/27/2022]
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.
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Affiliation(s)
- Paul N Ulrich
- 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
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30
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Gerasimaitė R, Sharma S, Desfougères Y, Schmidt A, Mayer A. Coupled synthesis and translocation restrains polyphosphate to acidocalcisome-like vacuoles and prevents its toxicity. J Cell Sci 2014; 127:5093-104. [DOI: 10.1242/jcs.159772] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Eukaryotes contain inorganic polyphosphate (polyP) and acidocalcisomes, which sequester polyP and store amino acids and divalent cations. Why polyP is sequestered in dedicated organelles has been unknown. We show that polyP produced in the cytosol of yeast becomes toxic. Reconstitution of polyP translocation with purified vacuoles, the acidocalcisomes of yeast, showed that cytosolic polyP cannot be imported whereas polyP produced by the VTC complex, an endogenous vacuolar polyP polymerase, is efficiently imported and does not interfere with growth. PolyP synthesis and import require an electrochemical gradient, probably as a driving force for polyP translocation. VTC exposes its catalytic domain to the cytosol and carries nine vacuolar transmembrane domains. Mutations in the VTC transmembrane regions, which likely constitute the translocation channel, block not only polyP translocation but also synthesis. Since they are far from the cytosolic catalytic domain of VTC, this suggests that the VTC complex obligatorily couples synthesis of polyP to its import in order to avoid toxic intermediates in the cytosol. Sequestration of otherwise toxic polyP may be one reason for the existence of acidocalcisomes in eukaryotes.
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Lander N, Ulrich PN, Docampo R. Trypanosoma brucei vacuolar transporter chaperone 4 (TbVtc4) is an acidocalcisome polyphosphate kinase required for in vivo infection. J Biol Chem 2013; 288:34205-34216. [PMID: 24114837 DOI: 10.1074/jbc.m113.518993] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Polyphosphate (polyP) is an anionic polymer of orthophosphate groups linked by high energy bonds that typically accumulates in acidic, calcium-rich organelles known as acidocalcisomes. PolyP synthesis in eukaryotes was unclear until it was demonstrated that the protein named Vtc4p (vacuolar transporter chaperone 4) is a long chain polyP kinase that localizes to the yeast vacuole. Here, we report that TbVtc4 (Vtc4 ortholog of Trypanosoma brucei) encodes, in contrast, a short chain polyP kinase that localizes to acidocalcisomes. The subcellular localization of TbVtc4 was demonstrated by fluorescence and electron microscopy of cell lines expressing TbVtc4 in its endogenous locus fused to an epitope tag and by purified polyclonal antibodies against TbVtc4. Recombinant TbVtc4 was expressed in bacteria, and polyP kinase activity was assayed in vitro. The in vitro growth of conditional knock-out bloodstream form trypanosomes (TbVtc4-KO) was significantly affected relative to the parental cell line. This mutant had reduced polyP kinase activity and short chain polyP content and was considerably less virulent in mice. The wild-type phenotype was recovered when an ectopic copy of the TbVtc4 gene was expressed in the presence of doxycycline. The mutant also exhibited a defect in volume recovery under osmotic stress conditions in vitro, underscoring the relevance of polyP in osmoregulation.
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Affiliation(s)
- Noelia Lander
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Paul N Ulrich
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602.
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Lott K, Li J, Fisk JC, Wang H, Aletta JM, Qu J, Read LK. Global proteomic analysis in trypanosomes reveals unique proteins and conserved cellular processes impacted by arginine methylation. J Proteomics 2013; 91:210-25. [PMID: 23872088 PMCID: PMC3935770 DOI: 10.1016/j.jprot.2013.07.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/26/2013] [Accepted: 07/07/2013] [Indexed: 12/14/2022]
Abstract
Arginine methylation is a common posttranslational modification with reported functions in transcription, RNA processing and translation, and DNA repair. Trypanosomes encode five protein arginine methyltransferases, suggesting that arginine methylation exerts widespread impacts on the biology of these organisms. Here, we performed a global proteomic analysis of Trypanosoma brucei to identify arginine methylated proteins and their sites of modification. Using an approach entailing two-dimensional chromatographic separation and alternating electron transfer dissociation and collision induced dissociation, we identified 1332 methylarginines in 676 proteins. The resulting data set represents the largest compilation of arginine methylated proteins in any organism to date. Functional classification revealed numerous arginine methylated proteins involved in flagellar function, RNA metabolism, DNA replication and repair, and intracellular protein trafficking. Thus, arginine methylation has the potential to impact aspects of T. brucei gene expression, cell biology, and pathogenesis. Interestingly, pathways with known methylated proteins in higher eukaryotes were identified in this study, but often different components of the pathway were methylated in trypanosomes. Methylarginines were often identified in glycine rich contexts, although exceptions to this rule were detected. Collectively, these data inform on a multitude of aspects of trypanosome biology and serve as a guide for the identification of homologous arginine methylated proteins in higher eukaryotes. BIOLOGICAL SIGNIFICANCE T. brucei is a protozoan parasite that causes lethal African sleeping sickness in humans and nagana in livestock, thereby imposing a significant medical and economic burden on sub-Saharan Africa. The parasite encounters very different environments as it cycles between mammalian and insect hosts, and must exert cellular responses to these varying milieus. One mechanism by which all cells respond to changing environments is through posttranslational modification of proteins. Arginine methylation is one such modification that can dramatically impact protein-protein and protein-nucleic acid interactions and subcellular localization of proteins. To define the breadth of arginine methylation in trypanosomes and identify target proteins, we performed a global proteomic analysis of arginine methylated proteins in insect stage T. brucei. We identified 1332 methylarginines in 676 proteins, generating the largest compilation of methylarginine containing proteins in any organism to date. Numerous arginine methylated proteins function in RNA and DNA related processes, suggesting this modification can impact T. brucei genome integrity and gene regulation at numerous points. Other processes that appear to be strongly influenced by arginine methylation are intracellular protein trafficking, signaling, protein folding and degradation, and flagellar function. The widespread nature of arginine methylation in trypanosomes highlights its potential to greatly affect parasite biology and pathogenesis.
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Affiliation(s)
- Kaylen Lott
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, United States of America
| | - Jun Li
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY, United States of America
| | - John C. Fisk
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, United States of America
| | - Hao Wang
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY, United States of America
| | - John M. Aletta
- CH3 BioSystems, New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, NY, United States of America
| | - Jun Qu
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY, United States of America
| | - Laurie K. Read
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, United States of America
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Acidocalcisomes of Trypanosoma brucei have an inositol 1,4,5-trisphosphate receptor that is required for growth and infectivity. Proc Natl Acad Sci U S A 2013; 110:1887-92. [PMID: 23319604 DOI: 10.1073/pnas.1216955110] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Acidocalcisomes are acidic calcium stores rich in polyphosphate and found in a diverse range of organisms. The mechanism of Ca(2+) release from these organelles was unknown. Here we present evidence that Trypanosoma brucei acidocalcisomes possess an inositol 1,4,5-trisphosphate receptor (TbIP(3)R) for Ca(2+) release. Localization studies in cell lines expressing TbIP(3)R in its endogenous locus fused to an epitope tag revealed its partial colocalization with the vacuolar proton pyrophosphatase, a marker of acidocalcisomes. IP(3) was able to stimulate Ca(2+) release from a chicken B-lymphocyte cell line in which the genes for all three vertebrate IP(3)Rs have been stably ablated (DT40-3KO) and that were stably expressing TbIP(3)R, providing evidence of its function. IP(3) was also able to release Ca(2+) from permeabilized trypanosomes or isolated acidocalcisomes and photolytic release of IP(3) in intact trypanosomes loaded with Fluo-4 elicited a transient Ca(2+) increase in their cytosol. Ablation of TbIP(3)R by RNA interference caused a significant reduction of IP(3)-mediated Ca(2+) release in trypanosomes and resulted in defects in growth in culture and infectivity in mice. Taken together, the data provide evidence of the presence of a functional IP(3)R as a Ca(2+) release channel in acidocalcisomes of trypanosomes and suggest that a Ca(2+) signaling pathway that involves acidocalcisomes is required for growth and establishment of infection.
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New insights into roles of acidocalcisomes and contractile vacuole complex in osmoregulation in protists. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 305:69-113. [PMID: 23890380 DOI: 10.1016/b978-0-12-407695-2.00002-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
While free-living protists are usually subjected to hyposmotic environments, parasitic protists are also in contact with hyperosmotic habitats. Recent work in one of these parasites, Trypanosoma cruzi, has revealed that its contractile vacuole complex, which usually collects and expels excess water as a mechanism of regulatory volume decrease after hyposmotic stress, has also a role in cell shrinking when the cells are submitted to hyperosmotic stress. Trypanosomes also have an acidic calcium store rich in polyphosphate (polyP), named the acidocalcisome, which is involved in their response to osmotic stress. Here, we review newly emerging insights on the role of acidocalcisomes and the contractile vacuole complex in the cellular response to hyposmotic and hyperosmotic stresses. We also review the current state of knowledge on the composition of these organelles and their other roles in calcium homeostasis and protein trafficking.
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Moreno-Sanchez D, Hernandez-Ruiz L, Ruiz FA, Docampo R. Polyphosphate is a novel pro-inflammatory regulator of mast cells and is located in acidocalcisomes. J Biol Chem 2012; 287:28435-44. [PMID: 22761438 PMCID: PMC3436523 DOI: 10.1074/jbc.m112.385823] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 06/25/2012] [Indexed: 01/07/2023] Open
Abstract
Polyphosphate (polyP) is a pro-inflammatory agent and a potent modulator of the human blood-clotting system. The presence of polyP of 60 phosphate units was identified in rat basophilic leukemia (RBL-2H3) mast cells using specific enzymatic assays, urea-polyacrylamide gel electrophoresis of cell extracts, and staining of cells with 4,6-diamidino-2-phenylindole (DAPI), and the polyP-binding domain of Escherichia coli exopolyphosphatase. PolyP co-localizes with serotonin- but not with histamine-containing granules. PolyP levels greatly decreased in mast cells stimulated to degranulate by IgE. Mast cell granules were isolated and found to be acidic and decrease their polyP content upon alkalinization. In agreement with these results, when RBL-2H3 mast cells were loaded with the fluorescent calcium indicator fura-2 acetoxymethyl ester to measure their intracellular Ca(2+) concentration ([Ca(2+)](i)), they were shown to possess a significant amount of Ca(2+) stored in an acidic compartment different from lysosomes. PolyP derived from RBL-2H3 mast cells stimulated bradykinin formation, and it was also detected in human basophils. All of these characteristics of mast cell granules, together with their known elemental composition, and high density, are similar to those of acidocalcisomes. The results suggest that mast cells polyP could be an important mediator of their pro-inflammatory and pro-coagulant activities.
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Affiliation(s)
- David Moreno-Sanchez
- From the Unidad de Investigación, Hospital Universitario Puerta del Mar, Facultad de Medicina, Universidad de Cádiz, 11009 Cádiz, Spain and
- the Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Laura Hernandez-Ruiz
- From the Unidad de Investigación, Hospital Universitario Puerta del Mar, Facultad de Medicina, Universidad de Cádiz, 11009 Cádiz, Spain and
- the Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Felix A. Ruiz
- From the Unidad de Investigación, Hospital Universitario Puerta del Mar, Facultad de Medicina, Universidad de Cádiz, 11009 Cádiz, Spain and
| | - Roberto Docampo
- the Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
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Silverman JS, Bangs JD. Form and function in the trypanosomal secretory pathway. Curr Opin Microbiol 2012; 15:463-8. [PMID: 22445359 DOI: 10.1016/j.mib.2012.03.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 03/01/2012] [Indexed: 01/31/2023]
Abstract
Recent advances in secretory biology of African trypanosomes reveal both similarities and striking differences with other model eukaryotic organisms. Secretion is streamlined for rapid and selective transport of the major cargo, VSG. Selectivity in the early and post-Golgi compartments is dependent on glycosylphosphatidyl inositol anchors. Streamlining includes reduced organellar abundance, and close association of ER exit sites with Golgi and with unique flagellar cytoskeletal elements that govern organellar replication and segregation. These elements include a novel centrin containing bilobe structure. Innate signals for post-Golgi sorting of biosynthetic lysosomal cargo trafficking have been defined, as have pathways for both biosynthetic and endocytic trafficking to the lysosome. Less well-defined secretory organelles such as the multivesicular body and acidocalcisomes are receiving closer scrutiny.
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Affiliation(s)
- Jason S Silverman
- Department of Medical Microbiology & Immunology, School of Medicine & Public Health, University of Wisconsin-Madison, Madison, WI 53706, United States
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Novel N-benzoyl-2-hydroxybenzamide disrupts unique parasite secretory pathway. Antimicrob Agents Chemother 2012; 56:2666-82. [PMID: 22354304 DOI: 10.1128/aac.06450-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Toxoplasma gondii is a protozoan parasite that can damage the human brain and eyes. There are no curative medicines. Herein, we describe our discovery of N-benzoyl-2-hydroxybenzamides as a class of compounds effective in the low nanomolar range against T. gondii in vitro and in vivo. Our lead compound, QQ-437, displays robust activity against the parasite and could be useful as a new scaffold for development of novel and improved inhibitors of T. gondii. Our genome-wide investigations reveal a specific mechanism of resistance to N-benzoyl-2-hydroxybenzamides mediated by adaptin-3β, a large protein from the secretory protein complex. N-Benzoyl-2-hydroxybenzamide-resistant clones have alterations of their secretory pathway, which traffics proteins to micronemes, rhoptries, dense granules, and acidocalcisomes/plant-like vacuole (PLVs). N-Benzoyl-2-hydroxybenzamide treatment also alters micronemes, rhoptries, the contents of dense granules, and, most markedly, acidocalcisomes/PLVs. Furthermore, QQ-437 is active against chloroquine-resistant Plasmodium falciparum. Our studies reveal a novel class of compounds that disrupts a unique secretory pathway of T. gondii, with the potential to be used as scaffolds in the search for improved compounds to treat the devastating diseases caused by apicomplexan parasites.
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