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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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Scholz-Starke J, Primo C, Yang J, Kandel R, Gaxiola RA, Hirschi KD. The flip side of the Arabidopsis type I proton-pumping pyrophosphatase (AVP1): Using a transmembrane H + gradient to synthesize pyrophosphate. J Biol Chem 2018; 294:1290-1299. [PMID: 30510138 DOI: 10.1074/jbc.ra118.006315] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/29/2018] [Indexed: 01/19/2023] Open
Abstract
Energy partitioning and plant growth are mediated in part by a type I H+-pumping pyrophosphatase (H+-PPase). A canonical role for this transporter has been demonstrated at the tonoplast where it serves a job-sharing role with V-ATPase in vacuolar acidification. Here, we investigated whether the plant H+-PPase from Arabidopsis also functions in "reverse mode" to synthesize PPi using the transmembrane H+ gradient. Using patch-clamp recordings on Arabidopsis vacuoles, we observed inward currents upon Pi application on the cytosolic side. These currents were strongly reduced in vacuoles from two independent H+-PPase mutant lines (vhp1-1 and fugu5-1) lacking the classical PPi-induced outward currents related to H+ pumping, whereas they were significantly larger in vacuoles with engineered heightened expression of the H+-PPase. Current amplitudes related to reverse-mode H+ transport depended on the membrane potential, cytosolic Pi concentration, and magnitude of the pH gradient across the tonoplast. Of note, experiments on vacuolar membrane-enriched vesicles isolated from yeast expressing the Arabidopsis H+-PPase (AVP1) demonstrated Pi-dependent PPi synthase activity in the presence of a pH gradient. Our work establishes that a plant H+-PPase can operate as a PPi synthase beyond its canonical role in vacuolar acidification and cytosolic PPi scavenging. We propose that the PPi synthase activity of H+-PPase contributes to a cascade of events that energize plant growth.
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Affiliation(s)
- Joachim Scholz-Starke
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Via De Marini 6, 16149 Genova, Italy.
| | - Cecilia Primo
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030
| | - Jian Yang
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030
| | - Raju Kandel
- School of Life Sciences, Arizona State University, Tempe, Arizona 85287
| | - Roberto A Gaxiola
- School of Life Sciences, Arizona State University, Tempe, Arizona 85287
| | - Kendal D Hirschi
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030.
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Wang CS, Jiang QT, Ma J, Wang XY, Wang JR, Chen GY, Qi PF, Peng YY, Lan XJ, Zheng YL, Wei YM. Characterization and expression analyses of the H⁺-pyrophosphatase gene in rye. J Genet 2017; 95:565-72. [PMID: 27659326 DOI: 10.1007/s12041-016-0664-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The H⁺-pyrophosphatase (H⁺-PPase) gene plays an important role in maintaining intracellular proton gradients. Here, we characterized the full-length complementary DNA (cDNA) and DNA of the H⁺-PPase gene ScHP1 in rye (Secale cereale L. 'Qinling'). We determined the subcellular localization of this gene and predicted the corresponding protein structure. We analysed the evolutionary relationship between ScHP1 and H⁺-PPase genes in other species, and did real-time quantitative polymerase chain reaction to explore the expression patterns of ScHP1 in rye plants subjected to N, P and K deprivation and to cold, high-salt and drought stresses. ScHP1 cDNA included a 2289 bp open reading frame (ORF) encoding 762 amino acid residues with 14 transmembrane domains. The genomic ScHP1 DNA was 4354 bp and contained eight exons and seven introns. ScHP1 was highly homologous with other members of the H⁺-PPase gene family. When the full-length ORF was inserted into the expression vector pA7-YFP, the fluorescent microscopy revealed that ScHP1-YFP fusion protein was located in the plasma membrane. Rye plants that were subjected to N deprivation, cold and high-salt stresses, ScHP1 expression was higher in the leaves than roots. Conversely, plants subjected to P and K deprivation and drought stress, ScHP1 expression was higher in the roots than leaves. Under all the investigated stress conditions, expression of ScHP1 was lower in the stem than in the leaves and roots. Our results imply that ScHP1 functions under abiotic stress response.
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Affiliation(s)
- Chang-Shui Wang
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, People's Republic of
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Tong C, Xiao B, Cheng S, Li W, Liao X, Luo S, Hao W. Generation and Identification of Peptide-Based Monoclonal Antibodies Against Vacuolar Proton Pyrophosphatase of Toxoplasma gondii. Monoclon Antib Immunodiagn Immunother 2016; 34:191-200. [PMID: 26090597 DOI: 10.1089/mab.2014.0093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Vacuolar proton pyrophosphatase (V-PPase), an electrogenic proton pump widely distributed in non-mammalian species, is one of the important targets for acidocalcisomes. In this study, a novel method of peptide-based antibody generation was performed to produce monoclonal antibodies (MAbs) against Toxoplasma gondii V-PPase. Three hybridomas were identified and confirmed by ELISA, Western blotting, and immunofluorescence. All of them can react with an 85 kDa band of T. gondii protein in purified acidocalcisomal fraction. The three MAbs were all specific to the synthetic peptide of YTKAADVGADLSGKNEYGMSEDDPRNPAC, corresponding to amino acids at the location of 292aa-320aa of TgVP1 amino acid sequence. These specific MAbs will be valuable tools for further study of T. gondii infection biology, pathogenesis, and host immune response.
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Affiliation(s)
- Chengbi Tong
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Bin Xiao
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Shasha Cheng
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Wei Li
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Xiaoqing Liao
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Shuhong Luo
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Wenbo Hao
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
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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: 56] [Impact Index Per Article: 7.0] [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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Identification and characterization of an ecto-pyrophosphatase activity in intact epimastigotes of Trypanosoma rangeli. PLoS One 2014; 9:e106852. [PMID: 25203926 PMCID: PMC4159237 DOI: 10.1371/journal.pone.0106852] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 08/09/2014] [Indexed: 02/06/2023] Open
Abstract
In this study, we performed the molecular and biochemical characterization of an ecto-enzyme present in Trypanosoma rangeli that is involved with the hydrolysis of extracellular inorganic pyrophosphate. PCR analysis identified a putative proton-pyrophosphatase (H+-PPase) in the epimastigote forms of T. rangeli. This protein was recognized with Western blot and flow cytometry analysis using an antibody against the H+-PPase of Arabidopsis thaliana. Immunofluorescence microscopy confirmed that this protein is located in the plasma membrane of T. rangeli. Biochemical assays revealed that the optimum pH for the ecto-PPase activity was 7.5, as previously demonstrated for other organisms. Sodium fluoride (NaF) and aminomethylenediphosphonate (AMDP) were able to inhibit approximately 75% and 90% of the ecto-PPase activity, respectively. This ecto-PPase activity was stimulated in a dose-dependent manner by MgCl2. In the presence of MgCl2, this activity was inhibited by millimolar concentrations of CaCl2. The ecto-PPase activity of T. rangeli decreased with increasing cell proliferation in vitro, thereby suggesting a role for this enzyme in the acquisition of inorganic phosphate (Pi). Moreover, this activity was modulated by the extracellular concentration of Pi and increased approximately two-fold when the cells were maintained in culture medium depleted of Pi. All of these results confirmed the occurrence of an ecto-PPase located in the plasma membrane of T. rangeli that possibly plays an important role in phosphate metabolism of this protozoan.
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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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Docampo R, Jimenez V, King-Keller S, Li ZH, Moreno SNJ. The role of acidocalcisomes in the stress response of Trypanosoma cruzi. ADVANCES IN PARASITOLOGY 2011; 75:307-24. [PMID: 21820562 DOI: 10.1016/b978-0-12-385863-4.00014-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Acidocalcisomes of Trypanosoma cruzi are acidic calcium-containing organelles rich in phosphorus in the form of pyrophosphate (PP(i)) and polyphosphate (poly P). Acidification of the organelles is driven by vacuolar proton pumps, one of which, the vacuolar-type proton pyrophosphatase, is absent in mammalian cells. A calcium ATPase is involved in calcium uptake, and an aquaporin is important for water transport. Enzymes involved in the synthesis and degradation of PPi and poly P are present within the organelle. Acidocalcisomes function as storage sites for cations and phosphorus, participate in PP(i) and poly P metabolism and volume regulation and are essential for virulence. A signalling pathway involving cyclic AMP generation is important for fusion of acidocalcisomes to the contractile vacuole complex, transference of aquaporin and volume regulation. This pathway is an excellent target for chemotherapy as shown by the effects of phosphodiesterase C inhibitors on parasite survival.
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Affiliation(s)
- Roberto Docampo
- Department of Cellular Biology and Center for Tropical and Global Emerging Diseases, University of Georgia, Athens, GA, USA
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9
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Heterologous expression and purification of membrane-bound pyrophosphatases. Protein Expr Purif 2011; 79:25-34. [DOI: 10.1016/j.pep.2011.05.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 05/20/2011] [Accepted: 05/26/2011] [Indexed: 12/18/2022]
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Abstract
Acidocalcisomes are acidic organelles containing calcium and a high concentration of phosphorus in the form of pyrophosphate (PP(i)) and polyphosphate (poly P). Organelles with these characteristics have been found from bacteria to human cells implying an early appearance and persistence over evolutionary time or their appearance by convergent evolution. Acidification of the organelles is driven by the presence of vacuolar proton pumps, one of which, the vacuolar proton pyrophosphatase, is absent in animals, where it is substituted by a vacuolar proton ATPase. A number of other pumps, antiporters, and channels have been described in acidocalcisomes of different species and are responsible for their internal content. Enzymes involved in the synthesis and degradation of PP(i) and poly P are present within the organelle. Acidocalcisomes function as storage sites for cations and phosphorus, and participate in PP(i) and poly P metabolism, calcium homeostasis, maintenance of intracellular pH, and osmoregulation. Experiments in which the acidocalcisome Ca(2+)-ATPase of different parasites were downregulated or eliminated, or acidocalcisome Ca(2+) was depleted revealed the importance of this store in Ca(2+) signaling needed for host invasion and virulence. Acidocalcisomes interact with other organelles in a number of organisms suggesting their association with the endosomal/lysosomal pathway, and are considered part of the lysosome-related group of organelles.
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Luoto HH, Belogurov GA, Baykov AA, Lahti R, Malinen AM. Na+-translocating membrane pyrophosphatases are widespread in the microbial world and evolutionarily precede H+-translocating pyrophosphatases. J Biol Chem 2011; 286:21633-42. [PMID: 21527638 DOI: 10.1074/jbc.m111.244483] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Membrane pyrophosphatases (PPases), divided into K(+)-dependent and K(+)-independent subfamilies, were believed to pump H(+) across cell membranes until a recent demonstration that some K(+)-dependent PPases function as Na(+) pumps. Here, we have expressed seven evolutionarily important putative PPases in Escherichia coli and estimated their hydrolytic, Na(+) transport, and H(+) transport activities as well as their K(+) and Na(+) requirements in inner membrane vesicles. Four of these enzymes (from Anaerostipes caccae, Chlorobium limicola, Clostridium tetani, and Desulfuromonas acetoxidans) were identified as K(+)-dependent Na(+) transporters. Phylogenetic analysis led to the identification of a monophyletic clade comprising characterized and predicted Na(+)-transporting PPases (Na(+)-PPases) within the K(+)-dependent subfamily. H(+)-transporting PPases (H(+)-PPases) are more heterogeneous and form at least three independent clades in both subfamilies. These results suggest that rather than being a curious rarity, Na(+)-PPases predominantly constitute the K(+)-dependent subfamily. Furthermore, Na(+)-PPases possibly preceded H(+)-PPases in evolution, and transition from Na(+) to H(+) transport may have occurred in several independent enzyme lineages. Site-directed mutagenesis studies facilitated the identification of a specific Glu residue that appears to be central in the transport mechanism. This residue is located in the cytoplasm-membrane interface of transmembrane helix 6 in Na(+)-PPases but shifted to within the membrane or helix 5 in H(+)-PPases. These results contribute to the prediction of the transport specificity and K(+) dependence for a particular membrane PPase sequence based on its position in the phylogenetic tree, identity of residues in the K(+) dependence signature, and position of the membrane-located Glu residue.
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Affiliation(s)
- Heidi H Luoto
- Department of Biochemistry and Food Chemistry, University of Turku, FIN-20014 Turku, Finland
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Miranda K, Pace DA, Cintron R, Rodrigues JCF, Fang J, Smith A, Rohloff P, Coelho E, de Haas F, de Souza W, Coppens I, Sibley LD, Moreno SNJ. Characterization of a novel organelle in Toxoplasma gondii with similar composition and function to the plant vacuole. Mol Microbiol 2010; 76:1358-75. [PMID: 20398214 DOI: 10.1111/j.1365-2958.2010.07165.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Toxoplasma gondii belongs to the phylum Apicomplexa and is an important cause of congenital disease and infection in immunocompromised patients. Like most apicomplexans, T. gondii possesses several plant-like features, such as the chloroplast-like organelle, the apicoplast. We describe and characterize a novel organelle in T. gondii tachyzoites, which is visible by light microscopy and possesses a broad similarity to the plant vacuole. Electron tomography shows the interaction of this vacuole with other organelles. The presence of a plant-like vacuolar proton pyrophosphatase (TgVP1), a vacuolar proton ATPase, a cathepsin L-like protease (TgCPL), an aquaporin (TgAQP1), as well as Ca(2+)/H(+) and Na(+)/H(+) exchange activities, supports similarity to the plant vacuole. Biochemical characterization of TgVP1 in enriched fractions shows a functional similarity to the respective plant enzyme. The organelle is a Ca(2+) store and appears to have protective effects against salt stress potentially linked to its sodium transport activity. In intracellular parasites, the organelle fragments, with some markers colocalizing with the late endosomal marker, Rab7, suggesting its involvement with the endocytic pathway. Studies on the characterization of this novel organelle will be relevant to the identification of novel targets for chemotherapy against T. gondii and other apicomplexan parasites as well.
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Affiliation(s)
- Kildare Miranda
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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Abstract
Acidocalcisomes are acidic organelles with a high concentration of phosphorus present as pyrophosphate (PP(i)) and polyphosphate (poly P) complexed with calcium and other cations. The acidocalcisome membrane contains a number of pumps (Ca(2+)-ATPase, V-H(+)-ATPase, H(+)-PPase), exchangers (Na(+)/H(+), Ca(2+)/H(+)), and channels (aquaporins), while its matrix contains enzymes related to PP(i) and poly P metabolism. Acidocalcisomes have been observed in pathogenic, as well as non-pathogenic prokaryotes and eukaryotes, e.g. Chlamydomonas reinhardtii, and Dictyostelium discoideum. Some of the potential functions of the acidocalcisome are the storage of cations and phosphorus, the participation of phosphorus in PP(i) and poly P metabolism, calcium homeostasis, maintenance of intracellular pH homeostasis, and osmoregulation. In addition, acidocalcisomes resemble lysosome-related organelles (LRO) from mammalian cells in many of their properties. For example, we found that platelet dense granules, which are LROs, are very similar to acidocalcisomes. They share a similar size, acidic properties, and both contain PP(i), poly P, and calcium. Recent work that indicates that they also share the system for targeting of their membrane proteins through adaptor protein 3 reinforces this concept. The fact that acidocalcisomes interact with other organelles in parasitic protists, e.g. the contractile vacuole in Trypanosoma cruzi, and other vacuoles observed in Toxoplasma gondii, suggests that these cellular compartments may be associated with the endosomal/lysosomal pathway.
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Affiliation(s)
- Silvia N J Moreno
- Department of Cellular Biology and Center for Tropical and Global Emerging Diseases, University of Georgia, Athens, 30602, USA.
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Jiménez-Jiménez C, Carrero-Lérida J, Sealey-Cardona M, Ruiz Pérez LM, Urbina JA, González Pacanowska D. Delta24(25)-sterol methenyltransferase: intracellular localization and azasterol sensitivity in Leishmania major promastigotes overexpressing the enzyme. Mol Biochem Parasitol 2008; 160:52-9. [PMID: 18485498 DOI: 10.1016/j.molbiopara.2008.03.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 03/19/2008] [Accepted: 03/31/2008] [Indexed: 11/25/2022]
Abstract
Trypanosomatids contain predominantly ergostane-based sterols, which differ from cholesterol, the main sterol in mammalian cells, in the presence of a methyl group in the 24 position. The methylation is initiated by S-adenosyl-L-methionine:Delta(24 (25))-sterol methenyltransferase, an enzyme present in protozoa, but absent in mammals. The importance of this enzyme is underscored by its potential as a drug target in the treatment of the leishmaniases. Here, we report studies concerning the intracellular distribution of sterol methenyltransferase in Leishmania major promastigotes and overexpressing cells using a specific antibody raised against highly purified recombinant protein. It was found by immunofluorescence and electron microscopy studies that in L. major wild-type cells sterol methenyltransferase was primarily associated to the endoplasmic reticulum. In addition to this location, the protein was incorporated into translucent vesicles presumably of the endocytic pathway. We also found in this study that cells overproducing the enzyme do not have increased resistance to the sterol methenyltransferase inhibitor 22, 26 azasterol.
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Affiliation(s)
- Carmen Jiménez-Jiménez
- Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, s/n 18100 Armilla, Granada, Spain
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Lustig Y, Vagima Y, Goldshmidt H, Erlanger A, Ozeri V, Vince J, McConville MJ, Dwyer DM, Landfear SM, Michaeli S. Down-regulation of the trypanosomatid signal recognition particle affects the biogenesis of polytopic membrane proteins but not of signal peptide-containing proteins. EUKARYOTIC CELL 2007; 6:1865-75. [PMID: 17715370 PMCID: PMC2043396 DOI: 10.1128/ec.00134-07] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Protein translocation across the endoplasmic reticulum is mediated by the signal recognition particle (SRP). In this study, the SRP pathway in trypanosomatids was down-regulated by two approaches: RNA interference (RNAi) silencing of genes encoding SRP proteins in Trypanosoma brucei and overexpression of dominant-negative mutants of 7SL RNA in Leptomonas collosoma. The biogenesis of both signal peptide-containing proteins and polytopic membrane proteins was examined using endogenous and green fluorescent protein-fused proteins. RNAi silencing of SRP54 or SRP68 in T. brucei resulted in reduced levels of polytopic membrane proteins, but no effect on the level of signal peptide-containing proteins was observed. When SRP deficiency was achieved in L. collosoma by overexpression of dominant-negative mutated 7SL RNA, a major effect was observed on polytopic membrane proteins but not on signal peptide-containing proteins. This study included two trypanosomatid species, tested various protein substrates, and induced depletion of the SRP pathway by affecting either the levels of SRP binding proteins or that of SRP RNA. Our results demonstrate that, as in bacteria but in contrast to mammalian cells, the trypanosome SRP is mostly essential for the biogenesis of membrane proteins.
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Affiliation(s)
- Yaniv Lustig
- The Mina and Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel
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Bäumer S, Lentes S, Gottschalk G, Deppenmeier U. Identification and analysis of proton-translocating pyrophosphatases in the methanogenic archaeon Methansarcina mazei. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2005; 1:1-7. [PMID: 15803653 PMCID: PMC2685546 DOI: 10.1155/2002/371325] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Analysis of genome sequence data from the methanogenic archaeon Methanosarcina mazei Gö1 revealed the existence of two open reading frames encoding proton-translocating pyrophosphatases (PPases). These open reading frames are linked by a 750-bp intergenic region containing TC-rich stretches and are transcribed in opposite directions. The corresponding polypeptides are referred to as Mvp1 and Mvp2 and consist of 671 and 676 amino acids, respectively. Both enzymes represent extremely hydrophobic, integral membrane proteins with 15 predicted transmembrane segments and an overall amino acid sequence similarity of 50.1%. Multiple sequence alignments revealed that Mvp1 is closely related to eukaryotic PPases, whereas Mvp2 shows highest homologies to bacterial PPases. Northern blot experiments with RNA from methanol-grown cells harvested in the mid-log growth phase indicated that only Mvp2 was produced under these conditions. Analysis of washed membranes showed that Mvp2 had a specific activity of 0.34 U mg (protein)(-1). Proton translocation experiments with inverted membrane vesicles prepared from methanol-grown cells showed that hydrolysis of 1 mol of pyrophosphate was coupled to the translocation of about 1 mol of protons across the cytoplasmic membrane. Appropriate conditions for mvp1 expression could not be determined yet. The pyrophosphatases of M. mazei Gö1 represent the first examples of this enzyme class in methanogenic archaea and may be part of their energy-conserving system.
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Affiliation(s)
- Sebastian Bäumer
- Abteilung Allgemeine Mikrobiologie, Institut für Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstr. 8, 37077 Göttingen, Germany
| | - Sabine Lentes
- Abteilung Allgemeine Mikrobiologie, Institut für Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstr. 8, 37077 Göttingen, Germany
| | - Gerhard Gottschalk
- Abteilung Allgemeine Mikrobiologie, Institut für Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstr. 8, 37077 Göttingen, Germany
- Göttingen Genomics Laboratory, Institut für Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstr. 8, 37077 Göttingen, Germany
| | - Uwe Deppenmeier
- Abteilung Allgemeine Mikrobiologie, Institut für Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstr. 8, 37077 Göttingen, Germany
- Corresponding author ()
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Soares Medeiros LCA, Moreira BLM, Miranda K, de Souza W, Plattner H, Hentschel J, Barrabin H. A proton pumping pyrophosphatase in acidocalcisomes of Herpetomonas sp. Mol Biochem Parasitol 2005; 140:175-82. [PMID: 15760657 DOI: 10.1016/j.molbiopara.2004.12.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2004] [Revised: 12/27/2004] [Accepted: 12/27/2004] [Indexed: 11/30/2022]
Abstract
Acidocalcisomes are acidic calcium storage organelles found in several microorganisms. They are characterized by their acidic nature, high electron density, high content of polyphosphates and several cations. Electron microscopy contrast tuned images of Herpetomonas sp. showed the presence of several electron dense organelles ranging from 100 to 300 nm in size. In addition, X-ray element mapping associated with energy-filtering transmission electron microscopy showed that most of the cations, namely Na, Mg, P, K, Fe and Zn, are located in their matrix. Using acridine orange as an indicator dye, a pyrophosphate-driven H+ uptake was measured in cells permeabilized by digitonin. This uptake has an optimal pH of 6.5-6.7 and was inhibited by sodium fluoride (NaF) and imidodiphosphate (IDP), two H+-pyrophosphatase inhibitors. H+ uptake was not promoted by ATP. Addition of 50 microM Ca2+ induced the release of H+, suggesting the presence of a Ca2+/H+ countertransport system in the membranes of the acidic compartments. Na+ was unable to release protons from the organelles. The pyrophosphate-dependent H+ uptake was dependent of ion K+ and inhibited by Na+ Herpetomonas sp. immunolabeled with monoclonal antibodies raised against a Trypanosoma cruzi V-H+-pyrophosphatase shows intense fluorescence in cytoplasmatic organelles of size and distribution similar to the electron-dense vacuoles. Together, these results suggest that the electron dense organelles found in Herpetomonas sp. are homologous to the acidocalcisomes described in other trypanosomatids. They possess a vacuolar H+-pyrophosphatase and a Ca2+/H+ antiport. However, in contrast to the other trypanosomatids so far studied, we were not able to measure any ATP promoted H+ transport in the acidocalcisomes of this parasite.
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Affiliation(s)
- Lia Carolina A Soares Medeiros
- Departmento de Bioquímica Médica, ICB-CCS Universidade Federal do Rio de Janeiro, UFRJ Ilha do Fundão, 21941-590 Rio de Janeiro, Brazil
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Perez-Castineira JR, Lopez-Marques RL, Villalba JM, Losada M, Serrano A. Functional complementation of yeast cytosolic pyrophosphatase by bacterial and plant H+-translocating pyrophosphatases. Proc Natl Acad Sci U S A 2002; 99:15914-9. [PMID: 12451180 PMCID: PMC138539 DOI: 10.1073/pnas.242625399] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two types of proteins that hydrolyze inorganic pyrophosphate (PPi), very different in both amino acid sequence and structure, have been characterized to date: soluble and membrane-bound proton-pumping pyrophosphatases (sPPases and H(+)-PPases, respectively). sPPases are ubiquitous proteins that hydrolyze PPi releasing heat, whereas H+-PPases, so far unidentified in animal and fungal cells, couple the energy of PPi hydrolysis to proton movement across biological membranes. The budding yeast Saccharomyces cerevisiae has two sPPases that are located in the cytosol and in the mitochondria. Previous attempts to knock out the gene coding for a cytosolic sPPase (IPP1) have been unsuccessful, thus suggesting that this protein is essential for growth. Here, we describe the generation of a conditional S. cerevisiae mutant (named YPC-1) whose functional IPP1 gene is under the control of a galactose-dependent promoter. Thus, YPC-1 cells become growth arrested in glucose but they regain the ability to grow on this carbon source when transformed with autonomous plasmids bearing diverse foreign H+-PPase genes under the control of a yeast constitutive promoter. The heterologously expressed H+-PPases are distributed among different yeast membranes, including the plasma membrane, functional complementation by these integral membrane proteins being consistently sensitive to external pH. These results demonstrate that hydrolysis of cytosolic PPi is essential for yeast growth and that this function is not substantially affected by the intrinsic characteristics of the PPase protein that accomplishes it. Moreover, this is, to our knowledge, the first direct evidence that H+-PPases can mediate net hydrolysis of PPi in vivo. YPC-1 mutant strain constitutes a convenient expression system to perform studies aimed at the elucidation of the structure-function relationships of this type of proton pumps.
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Affiliation(s)
- Jose R Perez-Castineira
- Instituto de Bioquimica Vegetal y Fotosintesis (Universidad de Sevilla-Consejo Superior de Investigaciones Cientificas), Avda Américo Vespucio sn, 41092 Sevilla, Spain
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Martinez R, Wang Y, Benaim G, Benchimol M, de Souza W, Scott DA, Docampo R. A proton pumping pyrophosphatase in the Golgi apparatus and plasma membrane vesicles of Trypanosoma cruzi. Mol Biochem Parasitol 2002; 120:205-13. [PMID: 11897126 DOI: 10.1016/s0166-6851(01)00456-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The proton pumping pyrophosphatase (H(+)-PPase) is an enzyme that has been identified in membranes of plant vacuoles, in the Golgi complex of plants and Chlamydomonas reinhardtii, and more recently in acidocalcisomes of different trypanosomatids and apicomplexan parasites. Immunofluorescence and immunoelectron microscopy studies using antibodies against the plant enzyme also suggested a plasma membrane localization in different stages of Trypanosoma cruzi. In this report we provide immunogold electron microscopy evidence of the presence of the H(+)-PPase in the Golgi complex and plasma membrane of epimastigotes of T. cruzi. Pyrophosphate promoted acidification of plasma membrane vesicles as determined using acridine orange. This activity was stimulated by K(+) ions, inhibited by the pyrophosphate analogs imidodiphosphate (IDP) and aminomethylenediphosphonate (AMDP) by KF, NaF and DCCD, and it had different responses to ions and inhibitors as compared with the activity present in acidocalcisomes. Surface localization of the H(+)-PPase was confirmed by experiments using biotinylation of cell surface proteins and immunoprecipitation with antibodies against H(+)-PPase. Taken together, these results are consistent with the presence of a functional H(+)-PPase in the plasma membrane of these parasites.
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Affiliation(s)
- Rosa Martinez
- Laboratory of Molecular Parasitology, Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, IL 61802, USA
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McConville MJ, Mullin KA, Ilgoutz SC, Teasdale RD. Secretory pathway of trypanosomatid parasites. Microbiol Mol Biol Rev 2002; 66:122-54; table of contents. [PMID: 11875130 PMCID: PMC120783 DOI: 10.1128/mmbr.66.1.122-154.2002] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The Trypanosomatidae comprise a large group of parasitic protozoa, some of which cause important diseases in humans. These include Trypanosoma brucei (the causative agent of African sleeping sickness and nagana in cattle), Trypanosoma cruzi (the causative agent of Chagas' disease in Central and South America), and Leishmania spp. (the causative agent of visceral and [muco]cutaneous leishmaniasis throughout the tropics and subtropics). The cell surfaces of these parasites are covered in complex protein- or carbohydrate-rich coats that are required for parasite survival and infectivity in their respective insect vectors and mammalian hosts. These molecules are assembled in the secretory pathway. Recent advances in the genetic manipulation of these parasites as well as progress with the parasite genome projects has greatly advanced our understanding of processes that underlie secretory transport in trypanosomatids. This article provides an overview of the organization of the trypanosomatid secretory pathway and connections that exist with endocytic organelles and multiple lytic and storage vacuoles. A number of the molecular components that are required for vesicular transport have been identified, as have some of the sorting signals that direct proteins to the cell surface or organelles in the endosome-vacuole system. Finally, the subcellular organization of the major glycosylation pathways in these parasites is reviewed. Studies on these highly divergent eukaryotes provide important insights into the molecular processes underlying secretory transport that arose very early in eukaryotic evolution. They also reveal unusual or novel aspects of secretory transport and protein glycosylation that may be exploited in developing new antiparasite drugs.
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Affiliation(s)
- Malcolm J McConville
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
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Abstract
Trans-membrane proton pumping is responsible for a myriad of physiological processes including the generation of proton motive force that drives bioenergetics. Among the various proton pumping enzymes, vacuolar pyrophosphatases (V-PPases) form a distinct class of proton pumps, which are characterised by their ability to translocate protons across a membrane by using the potential energy released by hydrolysis of the phosphoanhydride bond of inorganic pyrophosphate. Until recently, V-PPases were known to be the purview of only plant vacuoles and plasma membranes of phototrophic bacteria. Recent discoveries of V-PPases in kinetoplastid and apicomplexan parasites, however, have expanded our view of the evolutionary reach of these enzymes. The lack of V-PPases in the vertebrate hosts of these parasites makes them potentially excellent targets for developing broad-spectrum antiparasitic agents. This review surveys the current understanding of V-PPases in parasitic protozoa with an emphasis on malaria parasites. Topological predictions suggest remarkable similarity of the parasite enzymes to their plant homologues with 15-16 membrane spanning domains and conserved sequences shown to constitute critical catalytic residues. Remarkably, malaria parasites have been shown to possess two V-PPase genes, one is an apparent orthologue of the canonical plant enzyme, whereas the other is a more distantly related paralogue with homology to a recently identified new class of K+-insensitive plant V-PPases. V-PPases appear to localise both to the plasma membrane and cytoplasmic organelles believed to be acidocalcisomes or polyphosphate bodies. Gene transfer experiments suggest that one of the malarial V-PPases is predominantly localised to the surface of intraerythrocytic parasites. We suggest a model in which V-PPase localised to the malaria parasite plasma membrane may serve as an electrogenic pump utilising pyrophosphate as an energy source, thus sparing the more precious ATP. Searching for V-PPase inhibitors could prove fruitful as a novel means of antiparasitic chemotherapy.
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Affiliation(s)
- Michael T McIntosh
- Department of Microbiology and Immunology, MCP Hahnemann School of Medicine, Philadelphia, PA 19129, USA.
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Drozdowicz YM, Rea PA. Vacuolar H(+) pyrophosphatases: from the evolutionary backwaters into the mainstream. TRENDS IN PLANT SCIENCE 2001; 6:206-11. [PMID: 11335173 DOI: 10.1016/s1360-1385(01)01923-9] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Vacuolar-type H(+)-translocating inorganic pyrophosphatases have long been considered to be restricted to plants and to a few species of phototrophic bacteria. However, in recent investigations, these pyrophosphatases have been found in organisms as disparate as thermophilic Archaea and parasitic protists, and have resulted in the definition of a novel subclass in plants themselves. Among the many evolutionary and practical implications of these findings is the possibility that this research will spawn new approaches to the treatment of several prolific and debilitating parasite-mediated infections.
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Affiliation(s)
- Y M Drozdowicz
- Plant Science Institute, Dept Biology, University of Pennsylvania, 19104-6018, USA
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