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Solebo O, Ling L, Nwankwo I, Zhou J, Fu TM, Ke H. Plasmodium falciparum utilizes pyrophosphate to fuel an essential proton pump in the ring stage and the transition to trophozoite stage. PLoS Pathog 2023; 19:e1011818. [PMID: 38048362 PMCID: PMC10732439 DOI: 10.1371/journal.ppat.1011818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 12/20/2023] [Accepted: 11/10/2023] [Indexed: 12/06/2023] Open
Abstract
During asexual growth and replication cycles inside red blood cells, the malaria parasite Plasmodium falciparum primarily relies on glycolysis for energy supply, as its single mitochondrion performs little or no oxidative phosphorylation. Post merozoite invasion of a host red blood cell, the ring stage lasts approximately 20 hours and was traditionally thought to be metabolically quiescent. However, recent studies have shown that the ring stage is active in several energy-costly processes, including gene transcription, protein translation, protein export, and movement inside the host cell. It has remained unclear whether a low glycolytic flux alone can meet the energy demand of the ring stage over a long period post invasion. Here, we demonstrate that the metabolic by-product pyrophosphate (PPi) is a critical energy source for the development of the ring stage and its transition to the trophozoite stage. During early phases of the asexual development, the parasite utilizes Plasmodium falciparum vacuolar pyrophosphatase 1 (PfVP1), an ancient pyrophosphate-driven proton pump, to export protons across the parasite plasma membrane. Conditional deletion of PfVP1 leads to a delayed ring stage that lasts nearly 48 hours and a complete blockage of the ring-to-trophozoite transition before the onset of parasite death. This developmental arrest can be partially rescued by an orthologous vacuolar pyrophosphatase from Arabidopsis thaliana, but not by the soluble pyrophosphatase from Saccharomyces cerevisiae, which lacks proton pumping activities. Since proton-pumping pyrophosphatases have been evolutionarily lost in human hosts, the essentiality of PfVP1 suggests its potential as an antimalarial drug target. A drug target of the ring stage is highly desired, as current antimalarials have limited efficacy against this stage.
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Affiliation(s)
- Omobukola Solebo
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Liqin Ling
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Ikechukwu Nwankwo
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Jing Zhou
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Tian-Min Fu
- Department of Biological Chemistry and Pharmacology, The Ohio State University College of Medicine, Columbus, Ohio, United States of America
- The Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, United States of America
| | - Hangjun Ke
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
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2
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Cosse M, Seidel T. Plant Proton Pumps and Cytosolic pH-Homeostasis. FRONTIERS IN PLANT SCIENCE 2021; 12:672873. [PMID: 34177988 PMCID: PMC8220075 DOI: 10.3389/fpls.2021.672873] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/15/2021] [Indexed: 05/06/2023]
Abstract
Proton pumps create a proton motif force and thus, energize secondary active transport at the plasma nmembrane and endomembranes of the secretory pathway. In the plant cell, the dominant proton pumps are the plasma membrane ATPase, the vacuolar pyrophosphatase (V-PPase), and the vacuolar-type ATPase (V-ATPase). All these pumps act on the cytosolic pH by pumping protons into the lumen of compartments or into the apoplast. To maintain the typical pH and thus, the functionality of the cytosol, the activity of the pumps needs to be coordinated and adjusted to the actual needs. The cellular toolbox for a coordinated regulation comprises 14-3-3 proteins, phosphorylation events, ion concentrations, and redox-conditions. This review combines the knowledge on regulation of the different proton pumps and highlights possible coordination mechanisms.
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3
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Behrens CE, Smith KE, Iancu CV, Choe JY, Dean JV. Transport of Anthocyanins and other Flavonoids by the Arabidopsis ATP-Binding Cassette Transporter AtABCC2. Sci Rep 2019; 9:437. [PMID: 30679715 PMCID: PMC6345954 DOI: 10.1038/s41598-018-37504-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 11/29/2018] [Indexed: 01/16/2023] Open
Abstract
Flavonoids have important developmental, physiological, and ecological roles in plants and are primarily stored in the large central vacuole. Here we show that both an ATP-binding cassette (ABC) transporter(s) and an H+-antiporter(s) are involved in the uptake of cyanidin 3-O-glucoside (C3G) by Arabidopsis vacuolar membrane-enriched vesicles. We also demonstrate that vesicles isolated from yeast expressing the ABC protein AtABCC2 are capable of MgATP-dependent uptake of C3G and other anthocyanins. The uptake of C3G by AtABCC2 depended on the co-transport of glutathione (GSH). C3G was not altered during transport and a GSH conjugate was not formed. Vesicles from yeast expressing AtABCC2 also transported flavone and flavonol glucosides. We performed ligand docking studies to a homology model of AtABCC2 and probed the putative binding sites of C3G and GSH through site-directed mutagenesis and functional studies. These studies identified residues important for substrate recognition and transport activity in AtABCC2, and suggest that C3G and GSH bind closely, mutually enhancing each other’s binding. In conclusion, we suggest that AtABCC2 along with possibly other ABCC proteins are involved in the vacuolar transport of anthocyanins and other flavonoids in the vegetative tissue of Arabidopsis.
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Affiliation(s)
- Claire E Behrens
- Department of Biological Sciences, DePaul University, 2325 N. Clifton Ave., Chicago, 60614, IL, USA
| | - Kaila E Smith
- Department of Biological Sciences, DePaul University, 2325 N. Clifton Ave., Chicago, 60614, IL, USA
| | - Cristina V Iancu
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, 60064, IL, USA.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, 27834, USA
| | - Jun-Yong Choe
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, 60064, IL, USA. .,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, 27834, USA.
| | - John V Dean
- Department of Biological Sciences, DePaul University, 2325 N. Clifton Ave., Chicago, 60614, IL, USA.
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4
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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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5
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Raichaudhuri A. Arabidopsis thaliana MRP1 (AtABCC1) nucleotide binding domain contributes to arsenic stress tolerance with serine triad phosphorylation. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 108:109-120. [PMID: 27428365 DOI: 10.1016/j.plaphy.2016.07.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 07/07/2016] [Indexed: 05/20/2023]
Abstract
Multidrug resistance protein AtMRPs belong to the ATP binding cassette (ABC) transporter super family. ABC proteins are membrane proteins involved in the transport of a broad range of amphipathic organic anions across membranes. MRPs (ABCCs) are one of the highly represented subfamilies of ABC transporters. Plant MRPs also transport various glutathione conjugates across membranes. Arabidopsis thaliana MRP1 is already known to be involved in vacuolar storage of folates. Using heterologously expressed AtMRP1 in yeast and its C-terminal nucleotide binding domain (NBD2) in Escherichia coli, it has been shown that Casein kinase II (CKII) mediated phosphorylation is a potential regulator of AtMRP1 function. AtMRP1 showed enhanced tolerance towards arsenite As(III) in yeast. CKIIII/CKII mediated phosphorylation of AtMRP1 was found to be involved in As(III) mediated signaling. AtMRP1-NBD2 and its serine mutants showed distinct change in secondary structure in the presence of arsenite and methotrexate (MTX) controlled by serine triad phosphorylation. Results showed that AtMRP1 is important for vacuolar accumulation of antifolates as well as tolerance against arsenic, both of which involved phosphorylation in the serine triads at the C terminal NBD of AtMRP1. The experiments provide an important insight into the role of AtMRP1 serine triad phosphorylation under AsIII stress conditions.
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Affiliation(s)
- Ayan Raichaudhuri
- Department of Biotechnology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, West Bengal, India.
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6
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Sun X, Qi W, Yue Y, Ling H, Wang G, Song R. Maize ZmVPP5 is a truncated Vacuole H(+) -PPase that confers hypersensitivity to salt stress. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2016; 58:518-528. [PMID: 26728417 PMCID: PMC5071666 DOI: 10.1111/jipb.12462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 12/31/2015] [Indexed: 05/30/2023]
Abstract
In plants, Vacuole H(+) -PPases (VPPs) are important proton pumps and encoded by multiple genes. In addition to full-length VPPs, several truncated forms are expressed, but their biological functions are unknown. In this study, we functionally characterized maize vacuole H(+) -PPase 5 (ZmVPP5), a truncated VPP in the maize genome. Although ZmVPP5 shares high sequence similarity with ZmVPP1, ZmVPP5 lacks the complete structure of the conserved proton transport and the inorganic pyrophosphatase-related domain. Phylogenetic analysis suggests that ZmVPP5 might be derived from an incomplete gene duplication event. ZmVPP5 is expressed in multiple tissues, and ZmVPP5 was detected in the plasma membrane, vacuole membrane and nuclei of maize cells. The overexpression of ZmVPP5 in yeast cells caused a hypersensitivity to salt stress. Transgenic maize lines with overexpressed ZmVPP5 also exhibited the salt hypersensitivity phenotype. A yeast two-hybrid analysis identified the ZmBag6-like protein as a putative ZmVPP5-interacting protein. The results of bimolecular luminescence complementation (BiLC) assay suggest an interaction between ZmBag6-like protein and ZmVPP5 in vivo. Overall, this study suggests that ZmVPP5 might act as a VPP antagonist and participate in the cellular response to salt stress. Our study of ZmVPP5 has expanded the understanding of the origin and functions of truncated forms of plant VPPs.
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Affiliation(s)
- Xiaoliang Sun
- Shanghai key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Weiwei Qi
- Shanghai key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
- Coordinated Crop Biology Research Center(CBRC), Beijing 100193, China
| | - Yihong Yue
- Shanghai key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Huiling Ling
- Shanghai key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Gang Wang
- Shanghai key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
- Coordinated Crop Biology Research Center(CBRC), Beijing 100193, China
| | - Rentao Song
- Shanghai key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
- Coordinated Crop Biology Research Center(CBRC), Beijing 100193, China
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7
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Lv W, Banerjee B, Molland KL, Seleem MN, Ghafoor A, Hamed MI, Wan B, Franzblau SG, Mesecar AD, Cushman M. Synthesis of 3-(3-aryl-pyrrolidin-1-yl)-5-aryl-1,2,4-triazines that have antibacterial activity and also inhibit inorganic pyrophosphatase. Bioorg Med Chem 2014; 22:406-18. [PMID: 24315189 PMCID: PMC3914758 DOI: 10.1016/j.bmc.2013.11.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/23/2013] [Accepted: 11/05/2013] [Indexed: 11/26/2022]
Abstract
Inorganic pyrophosphatases are potential targets for the development of novel antibacterial agents. A pyrophosphatase-coupled high-throughput screening assay intended to detect o-succinyl benzoic acid coenzyme A (OSB CoA) synthetase inhibitors led to the unexpected discovery of a new series of novel inorganic pyrophosphatase inhibitors. Lead optimization studies resulted in a series of 3-(3-aryl-pyrrolidin-1-yl)-5-aryl-1,2,4-triazine derivatives that were prepared by an efficient synthetic pathway. One of the tetracyclic triazine analogues 22h displayed promising antibiotic activity against a wide variety of drug-resistant Staphylococcus aureus strains, as well as activity versus Mycobacterium tuberculosis and Bacillus anthracis, at a concentration that was not cytotoxic to mammalian cells.
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Affiliation(s)
- Wei Lv
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy and The Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States
| | - Biplab Banerjee
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy and The Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States
| | - Katrina L Molland
- Department of Biological Sciences and The Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States
| | - Mohamed N Seleem
- Department of Comparative Pathobiology, Purdue University College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, United States
| | - Adil Ghafoor
- Department of Comparative Pathobiology, Purdue University College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, United States
| | - Maha I Hamed
- Department of Comparative Pathobiology, Purdue University College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, United States
| | - Baojie Wan
- Institute for Tuberculosis Research, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, United States
| | - Scott G Franzblau
- Institute for Tuberculosis Research, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, United States
| | - Andrew D Mesecar
- Department of Biological Sciences and The Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States
| | - Mark Cushman
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy and The Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States.
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8
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Lee CH, Chen YW, Huang YT, Pan YJ, Lee CH, Lin SM, Huang LK, Lo YY, Huang YF, Hsu YD, Yen SC, Hwang JK, Pan RL. Functional Investigation of Transmembrane Helix 3 in H+-Translocating Pyrophosphatase. J Membr Biol 2013; 246:959-66. [DOI: 10.1007/s00232-013-9599-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 09/24/2013] [Indexed: 10/26/2022]
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9
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Kajander T, Kellosalo J, Goldman A. Inorganic pyrophosphatases: one substrate, three mechanisms. FEBS Lett 2013; 587:1863-9. [PMID: 23684653 DOI: 10.1016/j.febslet.2013.05.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 10/26/2022]
Abstract
Soluble inorganic pyrophosphatases (PPases) catalyse an essential reaction, the hydrolysis of pyrophosphate to inorganic phosphate. In addition, an evolutionarily ancient family of membrane-integral pyrophosphatases couple this hydrolysis to Na(+) and/or H(+) pumping, and so recycle some of the free energy from the pyrophosphate. The structures of the H(+)-pumping mung bean PPase and the Na(+)-pumping Thermotoga maritima PPase solved last year revealed an entirely novel membrane protein containing 16 transmembrane helices. The hydrolytic centre, well above the membrane, is linked by a charged "coupling funnel" to the ionic gate about 20Å away. By comparing the active sites, fluoride inhibition data and the various models for ion transport, we conclude that membrane-integral PPases probably use binding of pyrophosphate to drive pumping.
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Affiliation(s)
- Tommi Kajander
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
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10
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Plant Proton Pumps: Regulatory Circuits Involving H+-ATPase and H+-PPase. SIGNALING AND COMMUNICATION IN PLANTS 2011. [DOI: 10.1007/978-3-642-14369-4_2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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11
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Pan YJ, Lee CH, Hsu SH, Huang YT, Lee CH, Liu TH, Chen YW, Lin SM, Pan RL. The transmembrane domain 6 of vacuolar H(+)-pyrophosphatase mediates protein targeting and proton transport. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1807:59-67. [PMID: 20937245 DOI: 10.1016/j.bbabio.2010.10.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Revised: 10/01/2010] [Accepted: 10/05/2010] [Indexed: 11/28/2022]
Abstract
Vacuolar H(+)-pyrophosphatase (V-PPase; EC 3.6.1.1) plays a significant role in the maintenance of the pH in cytoplasm and vacuoles via proton translocation from the cytosol to the vacuolar lumen at the expense of PP(i) hydrolysis. The topology of V-PPase as predicted by TopPred II suggests that the catalytic site is putatively located in loop e and exposed to the cytosol. The adjacent transmembrane domain 6 (TM6) is highly conserved and believed to participate in the catalytic function and conformational stability of V-PPase. In this study, alanine-scanning mutagenesis along TM6 of the mung bean V-PPase was carried out to identify its structural and functional role. Mutants Y299A, A306S and L317A exhibited gross impairment in both PP(i) hydrolysis and proton translocation. Meanwhile, mutations at L307 and N318 completely abolished the targeting of the enzyme, causing broad cytosolic localization and implicating a possible role of these residues in protein translocation. The location of these amino acid residues was on the same side of the helix wheel, suggesting their involvement in maintaining the stability of enzyme conformation. G297A, E301A and A305S mutants showed declines in proton translocation but not in PP(i) hydrolysis, consequently resulting in decreases in the coupling efficiency. These amino acid residues cluster at one face of the helix wheel, indicating their direct/indirect participation in proton translocation. Taken together, these data indicate that TM6 is crucial to vacuolar H(+)-pyrophosphatase, probably mediating protein targeting, proton transport, and the maintenance of enzyme structure.
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Affiliation(s)
- Yih-Jiuan Pan
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsin Chu 30043, Taiwan, Republic of China
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12
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Huang YT, Liu TH, Chen YW, Lee CH, Chen HH, Huang TW, Hsu SH, Lin SM, Pan YJ, Lee CH, Hsu IC, Tseng FG, Fu CC, Pan RL. Distance variations between active sites of H(+)-pyrophosphatase determined by fluorescence resonance energy transfer. J Biol Chem 2010; 285:23655-64. [PMID: 20511234 DOI: 10.1074/jbc.m110.134916] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Homodimeric H(+)-pyrophosphatase (H(+)-PPase; EC 3.6.1.1) is a unique enzyme playing a pivotal physiological role in pH homeostasis of organisms. This novel H(+)-PPase supplies energy at the expense of hydrolyzing metabolic byproduct, pyrophosphate (PP(i)), for H(+) translocation across membrane. The functional unit for the translocation is considered to be a homodimer. Its putative active site on each subunit consists of PP(i) binding motif, Acidic I and II motifs, and several essential residues. In this investigation structural mapping of these vital regions was primarily determined utilizing single molecule fluorescence resonance energy transfer. Distances between two C termini and also two N termini on homodimeric subunits of H(+)-PPase are 49.3 + or - 4.0 and 67.2 + or - 5.7 A, respectively. Furthermore, putative PP(i) binding motifs on individual subunits are found to be relatively far away from each other (70.8 + or - 4.8 A), whereas binding of potassium and substrate analogue led them to closer proximity. Moreover, substrate analogue but not potassium elicits significant distance variations between two Acidic I motifs and two His-622 residues on homodimeric subunits. Taken together, this study provides the first quantitative measurements of distances between various essential motifs, residues, and putative active sites on homodimeric subunits of H(+)-PPase. A working model is accordingly proposed elucidating the distance variations of dimeric H(+)-PPase upon substrate binding.
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Affiliation(s)
- Yun-Tzu Huang
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsin Chu 30013, Taiwan
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13
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Hirono M, Maeshima M. Functional enhancement by single-residue substitution of Streptomyces coelicolor A3(2) H+-translocating pyrophosphatase. J Biochem 2009; 146:617-21. [PMID: 19628678 DOI: 10.1093/jb/mvp114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
H(+)-translocating pyrophosphatase converts energy from hydrolysis of pyrophosphate to active H(+) transport across biomembranes. Mutational analysis of Streptomyces coelicolor A3(2) enzyme revealed that amino acid substitution of Phe-388 and Ala-514 altered the enzyme activity. Both residues are located at the interface between the transmembrane domains and cytosolic loops, in which the catalytic domain exists. Systematic amino acid substitution was carried out using the Escherichia coli heterologous expression system. Two of the 38 mutant enzymes, F388Y and A514S, showed a high ratio of H(+)-pump to substrate hydrolysis without decrease in the substrate hydrolysis activity, indicating high energy-coupling efficiency.
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Affiliation(s)
- Megumi Hirono
- Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
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14
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Liu TH, Hsu SH, Huang YT, Lin SM, Huang TW, Chuang TH, Fan SK, Fu CC, Tseng FG, Pan RL. The proximity between C-termini of dimeric vacuolar H+-pyrophosphatase determined using atomic force microscopy and a gold nanoparticle technique. FEBS J 2009; 276:4381-94. [PMID: 19614743 DOI: 10.1111/j.1742-4658.2009.07146.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Vacuolar H(+)-translocating inorganic pyrophosphatase [vacuolar H(+)-pyrophosphatase (V-PPase); EC 3.6.1.1] is a homodimeric proton translocase; it plays a pivotal role in electrogenic translocation of protons from the cytosol to the vacuolar lumen, at the expense of PP(i) hydrolysis, for the storage of ions, sugars, and other metabolites. Dimerization of V-PPase is necessary for full proton translocation function, although the structural details of V-PPase within the vacuolar membrane remain uncertain. The C-terminus presumably plays a crucial role in sustaining enzymatic and proton-translocating reactions. We used atomic force microscopy to visualize V-PPases embedded in an artificial lipid bilayer under physiological conditions. V-PPases were randomly distributed in reconstituted lipid bilayers; approximately 43.3% of the V-PPase protrusions faced the cytosol, and 56.7% faced the vacuolar lumen. The mean height and width of the cytosolic V-PPase protrusions were 2.8 +/- 0.3 nm and 26.3 +/- 4.7 nm, whereas those of the luminal protrusions were 1.2 +/- 0.1 nm and 21.7 +/- 3.6 nm, respectively. Moreover, both C-termini of dimeric subunits of V-PPase are on the same side of the membrane, and they are close to each other, as visualized with antibody and gold nanoparticles against 6xHis tags on C-terminal ends of the enzyme. The distance between the V-PPase C-terminal ends was determined to be approximately 2.2 +/- 1.4 nm. Thus, our study is the first to provide structural details of a membrane-bound V-PPase dimer, revealing its adjacent C-termini.
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Affiliation(s)
- Tseng-Huang Liu
- Department of Life Sciences and Institute of Bioinformatics and Structural Biology, College of Life Sciences, National Tsing Hua University, Hsin Chu, Taiwan, ROC
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15
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Raichaudhuri A, Peng M, Naponelli V, Chen S, Sánchez-Fernández R, Gu H, Gregory JF, Hanson AD, Rea PA. Plant Vacuolar ATP-binding Cassette Transporters That Translocate Folates and Antifolates in Vitro and Contribute to Antifolate Tolerance in Vivo. J Biol Chem 2009; 284:8449-60. [PMID: 19136566 PMCID: PMC2659203 DOI: 10.1074/jbc.m808632200] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 01/05/2009] [Indexed: 02/01/2023] Open
Abstract
The vacuoles of pea (Pisum sativum) leaves and red beet (Beta vulgaris) storage root are major sites for the intracellular compartmentation of folates. In the light of these findings and preliminary experiments indicating that some plant multidrug resistance-associated protein (MRP) subfamily ATP-binding cassette transporters are able to transport compounds of this type, the Arabidopsis thaliana vacuolar MRP, AtMRP1 (AtABCC1), and its functional equivalent(s) in vacuolar membrane vesicles purified from red beet storage root were studied. In so doing, it has been determined that heterologously expressed AtMRP1 and its equivalents in red beet vacuolar membranes are not only competent in the transport of glutathione conjugates but also folate monoglutamates and antifolates as exemplified by pteroyl-l-glutamic acid and methotrexate (MTX), respectively. In agreement with the results of these in vitro transport measurements, analyses of atmrp1 T-DNA insertion mutants of Arabidopsis ecotypes Wassilewskia and Columbia disclose an MTX-hypersensitive phenotype. atmrp1 knock-out mutants are more sensitive than wild-type plants to growth retardation by nanomolar concentrations of MTX, and this is associated with impaired vacuolar antifolate sequestration. The vacuoles of protoplasts isolated from the leaves of Wassilewskia atmrp1 mutants accumulate 50% less [(3)H]MTX than the vacuoles of protoplasts from wild-type plants when incubated in media containing nanomolar concentrations of this antifolate, and vacuolar membrane-enriched vesicles purified from the mutant catalyze MgATP-dependent [(3)H]MTX uptake at only 40% of the capacity of the equivalent membrane fraction from wild-type plants. AtMRP1 and its counterparts in other plant species therefore have the potential for participating in the vacuolar accumulation of folates and related compounds.
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Affiliation(s)
- Ayan Raichaudhuri
- Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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16
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Hirono M, Nakanishi Y, Maeshima M. Identification of amino acid residues participating in the energy coupling and proton transport of Streptomyces coelicolor A3(2) H+-pyrophosphatase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:1401-11. [DOI: 10.1016/j.bbabio.2007.09.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2007] [Revised: 09/05/2007] [Accepted: 09/20/2007] [Indexed: 11/30/2022]
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17
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Hsiao YY, Pan YJ, Hsu SH, Huang YT, Liu TH, Lee CH, Lee CH, Liu PF, Chang WC, Wang YK, Chien LF, Pan RL. Functional roles of arginine residues in mung bean vacuolar H+-pyrophosphatase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:965-73. [PMID: 17543272 DOI: 10.1016/j.bbabio.2007.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 04/26/2007] [Accepted: 04/27/2007] [Indexed: 10/23/2022]
Abstract
Plant vacuolar H+-translocating inorganic pyrophosphatase (V-PPase EC 3.6.1.1) utilizes inorganic pyrophosphate (PPi) as an energy source to generate a H+ gradient potential for the secondary transport of ions and metabolites across the vacuole membrane. In this study, functional roles of arginine residues in mung bean V-PPase were determined by site-directed mutagenesis. Alignment of amino-acid sequence of K+-dependent V-PPases from several organisms showed that 11 of all 15 arginine residues were highly conserved. Arginine residues were individually substituted by alanine residues to produce R-->A-substituted V-PPases, which were then heterologously expressed in yeast. The characteristics of mutant variants were subsequently scrutinized. As a result, most R-->A-substituted V-PPases exhibited similar enzymatic activities to the wild-type with exception that R242A, R523A, and R609A mutants markedly lost their abilities of PPi hydrolysis and associated H+-translocation. Moreover, mutation on these three arginines altered the optimal pH and significantly reduced K+-stimulation for enzymatic activities, implying a conformational change or a modification in enzymatic reaction upon substitution. In particular, R242A performed striking resistance to specific arginine-modifiers, 2,3-butanedione and phenylglyoxal, revealing that Arg242 is most likely the primary target residue for these two reagents. The mutation at Arg242 also removed F- inhibition that is presumably derived from the interfering in the formation of substrate complex Mg2+-PPi. Our results suggest accordingly that active pocket of V-PPase probably contains the essential Arg242 which is embedded in a more hydrophobic environment.
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Affiliation(s)
- Yi-Yuong Hsiao
- Department of Life Sciences and Institute of Bioinformatics and Structural Biology, College of Life Sciences, National Tsing Hua University, Hsin Chu 30043, Taiwan
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18
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Hirono M, Nakanishi Y, Maeshima M. Essential amino acid residues in the central transmembrane domains and loops for energy coupling of Streptomyces coelicolor A3(2) H+-pyrophosphatase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:930-9. [PMID: 17498645 DOI: 10.1016/j.bbabio.2007.03.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 03/20/2007] [Accepted: 03/29/2007] [Indexed: 01/30/2023]
Abstract
The H+-translocating inorganic pyrophosphatase is a proton pump that hydrolyzes inorganic pyrophosphate. It consists of a single polypeptide with 14-17 transmembrane domains, and is found in a range of organisms. We focused on the second quarter region of Streptomyces coelicolor A3(2) H+-pyrophosphatase, which contains long conserved cytoplasmic loops. We prepared a library of 1536 mutants that were assayed for pyrophosphate hydrolysis and proton translocation. Mutant enzymes with low substrate hydrolysis and proton-pump activities were selected and their DNAs sequenced. Of these, 34 were single-residue substitution mutants. We generated 29 site-directed mutant enzymes and assayed their activity. The mutation of 10 residues in the fifth transmembrane domain resulted in low coupling efficiencies, and a mutation of Gly198 showed neither hydrolysis nor pumping activity. Four residues in cytoplasmic loop e were essential for substrate hydrolysis and efficient H+ translocation. Pro189, Asp281, and Val351 in the periplasmic loops were critical for enzyme function. Mutation of Ala357 in periplasmic loop h caused a selective reduction of proton-pump activity. These low-efficiency mutants reflect dysfunction of the energy-conversion and/or proton-translocation activities of H+-pyrophosphatase. Four critical residues were also found in transmembrane domain 6, three in transmembrane domain 7, and five in transmembrane domains 8 and 9. These results suggest that transmembrane domain 5 is involved in enzyme function, and that energy coupling is affected by several residues in the transmembrane domains, as well as in the cytoplasmic and periplasmic loops. H+-pyrophosphatase activity might involve dynamic linkage between the hydrophilic and transmembrane domains.
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Affiliation(s)
- Megumi Hirono
- Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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19
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Mullan DJ, Colmer TD, Francki MG. Arabidopsis–rice–wheat gene orthologues for Na+ transport and transcript analysis in wheat–L. elongatum aneuploids under salt stress. Mol Genet Genomics 2006; 277:199-212. [PMID: 17103227 DOI: 10.1007/s00438-006-0184-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Accepted: 10/17/2006] [Indexed: 10/23/2022]
Abstract
Lophopyrum elongatum is a wild relative of wheat that provides a source of novel genes for improvement of the salt tolerance of bread wheat. Improved Na(+) 'exclusion' is associated with salt tolerance in a wheat-L. elongatum amphiploid, in which a large proportion (ca. 50%) of the improved regulation of leaf Na(+) concentrations is controlled by chromosome 3E. In this study, genes that might control Na(+) accumulation, such as for transporters responsible for Na(+) entry (HKT1) and exit (SOS1) from cells, or compartmentalisation within vacuoles (NHX1, NHX5, AVP1, AVP2) in the model plant, Arabidopsis thaliana, were targeted for comparative analyses in wheat. Putative rice orthologues were identified and characterised as a means to bridge the large evolutionary distance between genomes from the model dicot and the more complex grass species. Wheat orthologues were identified through BLAST searching to identify either FL-cDNAs or ESTs and were subsequently used to design primers to amplify genomic DNA. The probable orthologous status of the wheat genes was confirmed through demonstration of similar intron-exon structure with their counterparts in Arabidopsis and rice. The majority of exons for Arabidopsis, rice and wheat orthologues of NHX1, NHX5 and SOS1 were conserved except for those at the amino and carboxy terminal ends. However, additional exons were identified in the predicted NHX1 and SOS1 genes of rice and wheat, as compared with Arabidopsis, indicating gene rearrangement events during evolution from a common ancestor. Nullisomic-tetrasomic, deletion and addition lines in wheat were used to assign gene sequences to chromosome regions in wheat and L. elongatum. Most sequences were assigned to homoeologous chromosomes, however, in some instances, such as for SOS1, genes were mapped to other unpredicted locations. Differential transcript abundance under salt stress indicated a complex pattern of expression for wheat orthologues that may regulate Na(+) accumulation in wheat lines containing chromosomes from L. elongatum. The identification of wheat orthologues to well characterized Arabidopsis genes, map locations and gene expression profiles increases our knowledge on the complex mechanisms regulating Na(+) transport in wheat and wheat-L. elongatum lines under salt stress.
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Affiliation(s)
- Daniel J Mullan
- School of Plant Biology, Faculty of Natural and Agricultural Sciences, University of Western Australia, Crawley, WA, 6009, Australia
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20
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Zancani M, Skiera LA, Sanders D. Roles of basic residues and salt-bridge interaction in a vacuolar H+-pumping pyrophosphatase (AVP1) from Arabidopsis thaliana. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1768:311-6. [PMID: 17113565 DOI: 10.1016/j.bbamem.2006.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 09/14/2006] [Accepted: 10/10/2006] [Indexed: 10/24/2022]
Abstract
To investigate the possible role of basic residues in H+ translocation through vacuolar-type H+-pumping pyrophosphatases (V-PPases), conserved arginine and lysine residues predicted to reside within or close to transmembrane domains of an Arabidopsis thaliana V-PPase (AVP1) were subjected to site-directed mutagenesis. One of these mutants (K461A) exhibited a "decoupled" phenotype in which proton-pumping but not hydrolysis was inhibited. Similar results were reported previously for an E427Q mutant, resulting in the proposal that E427 might be involved in proton translocation. However, the double mutant E427K/K461E has a wild type phenotype, suggesting that E427 and K461 form a stabilising salt bridge, but that neither residue plays a critical role in proton translocation.
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Affiliation(s)
- Marco Zancani
- Biology Department (Area 9), University of York, PO Box 373, York YO10 5YW, UK.
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21
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Romanyuk ND, Rigden DJ, Vatamaniuk OK, Lang A, Cahoon RE, Jez JM, Rea PA. Mutagenic definition of a papain-like catalytic triad, sufficiency of the N-terminal domain for single-site core catalytic enzyme acylation, and C-terminal domain for augmentative metal activation of a eukaryotic phytochelatin synthase. PLANT PHYSIOLOGY 2006; 141:858-69. [PMID: 16714405 PMCID: PMC1489916 DOI: 10.1104/pp.106.082131] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Phytochelatin (PC) synthases are gamma-glutamylcysteine (gamma-Glu-Cys) dipeptidyl transpeptidases that catalyze the synthesis of heavy metal-binding PCs, (gamma-Glu-Cys)nGly polymers, from glutathione (GSH) and/or shorter chain PCs. Here it is shown through investigations of the enzyme from Arabidopsis (Arabidopsis thaliana; AtPCS1) that, although the N-terminal half of the protein, alone, is sufficient for core catalysis through the formation of a single-site enzyme acyl intermediate, it is not sufficient for acylation at a second site and augmentative stimulation by free Cd2+. A purified N-terminally hexahistidinyl-tagged AtPCS1 truncate containing only the first 221 N-terminal amino acid residues of the enzyme (HIS-AtPCS1_221tr) is competent in the synthesis of PCs from GSH in media containing Cd2+ or the synthesis of S-methyl-PCs from S-methylglutathione in media devoid of heavy metal ions. However, whereas its full-length hexahistidinyl-tagged equivalent, HIS-AtPCS1, undergoes gamma-Glu-Cys acylation at two sites during the Cd2+-dependent synthesis of PCs from GSH and is stimulated by free Cd2+ when synthesizing S-methyl-PCs from S-methylglutathione, HIS-AtPCS1_221tr undergoes gamma-Glu-Cys acylation at only one site when GSH is the substrate and is not directly stimulated, but instead inhibited, by free Cd2+ when S-methylglutathione is the substrate. Through the application of sequence search algorithms capable of detecting distant homologies, work we reported briefly before but not in its entirety, it has been determined that the N-terminal half of AtPCS1 and its equivalents from other sources have the hallmarks of a papain-like, Clan CA Cys protease. Whereas the fold assignment deduced from these analyses, which substantiates and is substantiated by the recent determination of the crystal structure of a distant prokaryotic PC synthase homolog from the cyanobacterium Nostoc, is capable of explaining the strict requirement for a conserved Cys residue, Cys-56 in the case of AtPCS1, for formation of the biosynthetically competent gamma-Glu-Cys enzyme acyl intermediate, the primary data from experiments directed at determining whether the other two residues, His-162 and Asp-180 of the putative papain-like catalytic triad of AtPCS1, are essential for catalysis have yet to be presented. This shortfall in our basic understanding of AtPCS1 is addressed here by the results of systematic site-directed mutagenesis studies that demonstrate that not only Cys-56 but also His-162 and Asp-180 are indeed required for net PC synthesis. It is therefore established experimentally that AtPCS1 and, by implication, other eukaryotic PC synthases are papain Cys protease superfamily members but ones, unlike their prokaryotic counterparts, which, in addition to having a papain-like N-terminal catalytic domain that undergoes primary gamma-Glu-Cys acylation, contain an auxiliary metal-sensing C-terminal domain that undergoes secondary gamma-Glu-Cys acylation.
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Affiliation(s)
- Nataliya D Romanyuk
- Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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22
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Au KM, Barabote RD, Hu KY, Saier MH. Evolutionary appearance of H+-translocating pyrophosphatases. Microbiology (Reading) 2006; 152:1243-1247. [PMID: 16622041 DOI: 10.1099/mic.0.28581-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Ka M Au
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA
| | - Ravi D Barabote
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA
| | - Kuang Yu Hu
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA
| | - Milton H Saier
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA
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23
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Van RC, Pan YJ, Hsu SH, Huang YT, Hsiao YY, Pan RL. Role of transmembrane segment 5 of the plant vacuolar H+-pyrophosphatase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1709:84-94. [PMID: 16018964 DOI: 10.1016/j.bbabio.2005.05.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Revised: 05/26/2005] [Accepted: 05/31/2005] [Indexed: 11/20/2022]
Abstract
Vacuolar H+-translocating inorganic pyrophosphatase (V-PPase; EC 3.6.1.1) is a homodimeric proton translocase consisting of a single type of polypeptide with a molecular mass of approximately 81 kDa. Topological analysis tentatively predicts that mung bean V-PPase contains 14 transmembrane domains. Alignment analysis of V-PPase demonstrated that the transmembrane domain 5 (TM5) of the enzyme is highly conserved in plants and located at the N-terminal side of the putative substrate-binding loop. The hydropathic analysis of V-PPase showed a relatively lower degree of hydrophobicity in the TM5 region as compared to other domains. Accordingly, it appears that TM5 is probably involved in the proton translocation of V-PPase. In this study, we used site-directed mutagenesis to examine the functional role of amino acid residues in TM5 of V-PPase. A series of mutants singly replaced by alanine residues along TM5 were constructed and over-expressed in Saccharomyces cerevisiae; they were then used to determine their enzymatic activities and proton translocations. Our results indicate that several mutants displayed minor variations in enzymatic properties, while others including those mutated at E225, a GYG motif (residues from 229 to 231), A238, and R242, showed a serious decline in enzymatic activity, proton translocation, and coupling efficiency of V-PPase. Moreover, the mutation at Y230 relieved several cation effects on the V-PPase. The GYG motif presumably plays a significant role in maintaining structure and function of V-PPase.
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Affiliation(s)
- Ru C Van
- Department of Life Sciences and Institute of Bioinformatics and Structural Biology, College of Life Sciences, National Tsing Hua University, Hsin Chu 30043, Taiwan, Republic of China
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24
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Lin HH, Pan YJ, Hsu SH, Van RC, Hsiao YY, Chen JH, Pan RL. Deletion mutation analysis on C-terminal domain of plant vacuolar H+-pyrophosphatase. Arch Biochem Biophys 2005; 442:206-13. [PMID: 16185650 DOI: 10.1016/j.abb.2005.08.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 08/15/2005] [Accepted: 08/15/2005] [Indexed: 10/25/2022]
Abstract
Vacuolar H(+)-translocating inorganic pyrophosphatase (V-PPase; EC 3.6.1.1) is a homodimeric proton-translocase; it contains a single type of polypeptide of approximately 81kDa. A line of evidence demonstrated that the carboxyl terminus of V-PPase is relatively conserved in various plant V-PPases and presumably locates in the vicinity of the catalytic site. In this study, we attempt to identify the roles of the C-terminus of V-PPase by generating a series of C-terminal deletion mutants over-expressed in Saccharomyces cerevisiae, and determining their enzymatic and proton translocating reactions. Our results showed that the deletion mutation at last 5 amino acids in the C-terminus (DeltaC5) induced a dramatic decline in enzymatic activity, proton translocation, and coupling efficiency of V-PPase; but the mutant lacking last 10 amino acids (DeltaC10) retained about 60-70% of the enzymatic activity of wild-type. Truncation of the C-terminus by more than 10 amino acids completely abolished the enzymatic activity and proton translocation of V-PPase. Furthermore, the DeltaC10 mutant displayed a shift in T(1/2) (pretreatment temperature at which half enzymatic activity is observed) but not the optimal pH for PP(i) hydrolytic activity. The deletion of the C-terminus substantially modified apparent K(+) binding constant, but exert no significant changes in the Na(+)-, F(-)-, and Ca(2+)-inhibition of the enzymatic activity of V-PPase. Taken together, we speculate that the C-terminus of V-PPase may play a crucial role in sustaining enzymatic activity and is likely involved in the K(+)-regulation of the enzyme in an indirect manner.
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Affiliation(s)
- Hsin Hung Lin
- Department of Life Sciences and Institute of Bioinformatics and Structural Biology, College of Life Sciences, National Tsing Hua University, Hsin Chu 30043, Taiwan, ROC
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25
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Moraes Moreira BL, Soares Medeiros LCA, Miranda K, de Souza W, Hentschel J, Plattner H, Barrabin H. Kinetics of pyrophosphate-driven proton uptake by acidocalcisomes of Leptomonas wallacei. Biochem Biophys Res Commun 2005; 334:1206-13. [PMID: 16039991 DOI: 10.1016/j.bbrc.2005.06.205] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 06/27/2005] [Indexed: 11/22/2022]
Abstract
In this work, we show the kinetics of pyrophosphate-driven H+ uptake by acidocalcisomes in digitonin-permeabilized promastigotes of Leptomonas wallacei. The vacuolar proton pyrophosphatase activity was optimal in the pH range of 7.5-8.0, was inhibited by imidiodiphosphate, and was completely dependent on K+ and PPi. H+ was released with the addition of Ca2+, suggesting the presence of a Ca2+/H+ antiport. In addition, X-ray elemental mapping associated with energy-filtering transmission electron microscopy showed that most of the Ca, Na, Mg, P, K, Fe, and Zn were located in acidocalcisomes. L. wallacei immunolabeled with antibodies against Trypanosoma cruzi pyrophosphatase show intense fluorescence in cytoplasmatic organelles of size and distribution similar to the acidocalcisomes. Altogether, the results show that L. wallacei acidocalcisomes possess a H+-pyrophosphatase with characteristics of type I V-H+-PPase. However, we did not find any evidence, either for the presence of H+-ATPases or for Na+/H+ exchangers in these acidocalcisomes.
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26
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Mimura H, Nakanishi Y, Maeshima M. Oligomerization of H(+)-pyrophosphatase and its structural and functional consequences. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1708:393-403. [PMID: 15953583 DOI: 10.1016/j.bbabio.2005.05.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Revised: 04/18/2005] [Accepted: 05/10/2005] [Indexed: 11/23/2022]
Abstract
The H(+)-pyrophosphatase (H(+)-PPase) consists of a single polypeptide, containing 16 or 17 transmembrane domains. To determine the higher order oligomeric state of Streptomyces coelicolor H(+)-PPase, we constructed a series of cysteine substitution mutants and expressed them in Escherichia coli. Firstly, we analyzed the formation of disulfide bonds, promoted by copper, in mutants with single cysteine substitutions. 28 of 39 mutants formed disulfide bonds, including S545C, a substitution at the periplasmic side. The formation of intermolecular disulfide bonds suppressed the enzyme activity of several, where the substituted residues were located in the cytosol. Creating disulfide links in the cytosol may interfere with the enzyme's catalytic function. Secondly, we prepared double mutants by introducing second cysteine substitutions into the S545C mutant. These double-cysteine mutants produced cross-linked complexes, estimated to be at least tetramers and possibly hexamers. Thirdly, we co-expressed epitope-tagged, wild type, and inactive mutant H(+)-PPases in E. coli and confirmed the formation of oligomers by co-purifying one subunit using the epitope tag used to label the other. The enzyme activity of these oligomers was markedly suppressed. We propose that H(+)-PPase is present as an oligomer made up of at least two or three sets of dimers.
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Affiliation(s)
- Hisatoshi Mimura
- Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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27
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Hirono M, Mimura H, Nakanishi Y, Maeshima M. Expression of Functional Streptomyces coelicolor H+-Pyrophosphatase and Characterization of Its Molecular Properties. ACTA ACUST UNITED AC 2005; 138:183-91. [PMID: 16091593 DOI: 10.1093/jb/mvi112] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
H(+)-translocating pyrophosphatases (H(+)-PPases) are proton pumps that are found in many organisms, including plants, bacteria and protozoa. Streptomyces coelicolor is a soil bacterium that produces several useful antibiotics. Here we investigated the properties of the H(+)-PPase of S. coelicolor by expressing a synthetic DNA encoding the amino-acid sequence of the H(+)-PPase in Escherichia coli. The H(+)-PPase from E. coli membranes was active at a relatively high pH, stable up to 50 degrees C, and sensitive to N-ethylmaleimide, N,N'-dicyclohexylcarbodiimide and acylspermidine. Enzyme activity increased by 60% in the presence of 120 mM K(+), which was less than the stimulation observed with plant vacuolar H(+)-PPases (type I). Substitutions of Lys-507 in the Gly-Gln-x-x-(Ala/Lys)-Ala motif, which is thought to determine the K(+) requirement of H(+)-PPases, did not alter its K(+) dependence, suggesting that other residues control this feature of the S. coelicolor enzyme. The H(+)-PPase was detected during early growth and was present mainly on the plasma membrane and to a lesser extent on intracellular membranous structures.
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Affiliation(s)
- Megumi Hirono
- Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University
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28
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Mimura H, Nakanishi Y, Maeshima M. Disulfide-bond formation in the H+-pyrophosphatase ofStreptomyces coelicolorand its implications for redox control and enzyme structure. FEBS Lett 2005; 579:3625-31. [PMID: 15963991 DOI: 10.1016/j.febslet.2005.05.045] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Revised: 05/11/2005] [Accepted: 05/11/2005] [Indexed: 11/16/2022]
Abstract
Redox control of disulfide-bond formation in the H+-pyrophosphatase of Streptomyces coelicolor was investigated using cysteine mutants expressed in Escherichia coli. The wild-type enzyme, but not a cysteine-less mutant, was reversibly inactivated by oxidation. To determine the residues involved in oxidative inactivation, different cysteine residues were replaced. Analysis with a cysteine-modifying reagent revealed that the formation of a disulfide bond between cysteines 253 and 621 was responsible for enzyme inactivation. This result suggests that residues in different cytoplasmic loops are close to each other in the tertiary structure. Both cysteine residues are conserved in K+-independent (type II) H+-pyrophosphatases.
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Affiliation(s)
- Hisatoshi Mimura
- Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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29
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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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30
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Malinen AM, Belogurov GA, Salminen M, Baykov AA, Lahti R. Elucidating the Role of Conserved Glutamates in H+-pyrophosphatase of Rhodospirillum rubrum. J Biol Chem 2004; 279:26811-6. [PMID: 15107429 DOI: 10.1074/jbc.m404154200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
H(+)-pyrophosphatase (H(+)-PPase) catalyzes pyrophosphate-driven proton transport against the electrochemical potential gradient in various biological membranes. All 50 of the known H(+)-PPase amino acid sequences contain four invariant glutamate residues. In this study, we use site-directed mutagenesis in conjunction with functional studies to determine the roles of the glutamate residues Glu(197), Glu(202), Glu(550), and Glu(649) in the H(+)-PPase of Rhodospirillum rubrum (R-PPase). All residues were replaced with Asp and Ala. The resulting eight variant R-PPases were expressed in Escherichia coli and isolated as inner membrane vesicles. All substitutions, except E202A, generated enzymes capable of PP(i) hydrolysis and PP(i)-energized proton translocation, indicating that the negative charge of Glu(202) is essential for R-PPase function. The hydrolytic activities of all other PPase variants were impaired at low Mg(2+) concentrations but were only slightly affected at high Mg(2+) concentrations, signifying that catalysis proceeds through a three-metal pathway in contrast to wild-type R-PPase, which employs both two- and three-metal pathways. Substitution of Glu(197), Glu(202), and Glu(649) resulted in decreased binding affinity for the substrate analogues aminomethylenediphosphonate and methylenediphosphonate, indicating that these residues are involved in substrate binding as ligands for bridging metal ions. Following the substitutions of Glu(550) and Glu(649), R-PPase was more susceptible to inactivation by the sulfhydryl reagent mersalyl, highlighting a role of these residues in maintaining enzyme tertiary structure. None of the substitutions affected the coupling of PP(i) hydrolysis to proton transport.
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Affiliation(s)
- Anssi M Malinen
- Department of Biochemistry and Food Chemistry, University of Turku, FIN-20014 Turku, Finland
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31
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Hsiao YY, Van RC, Hung SH, Lin HH, Pan RL. Roles of histidine residues in plant vacuolar H+-pyrophosphatase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1608:190-9. [PMID: 14871497 DOI: 10.1016/j.bbabio.2004.01.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2003] [Revised: 01/05/2004] [Accepted: 01/06/2004] [Indexed: 11/18/2022]
Abstract
Vacuolar proton pumping pyrophosphatase (H(+)-PPase; EC 3.6.1.1) plays a pivotal role in electrogenic translocation of protons from cytosol to the vacuolar lumen at the expense of PP(i) hydrolysis. Alignment analysis on amino acid sequence demonstrates that vacuolar H(+)-PPase of mung bean contains six highly conserved histidine residues. Previous evidence indicated possible involvement of histidine residue(s) in enzymatic activity and H(+)-translocation of vacuolar H(+)-PPase as determined by using histidine specific modifier, diethylpyrocarbonate [J. Protein Chem. 21 (2002) 51]. In this study, we further attempted to identify the roles of histidine residues in mung bean vacuolar H(+)-PPase by site-directed mutagenesis. A line of mutants with histidine residues singly replaced by alanine was constructed, over-expressed in Saccharomyces cerevisiae, and then used to determine their enzymatic activities and proton translocations. Among the mutants scrutinized, only the mutation of H716 significantly decreased the enzymatic activity, the proton transport, and the coupling ratio of vacuolar H(+)-PPase. The enzymatic activity of H716A is relatively resistant to inhibition by diethylpyrocarbonate as compared to wild-type and other mutants, indicating that H716 is probably the target residue for the attack by this modifier. The mutation at H716 of V-PPase shifted the optimum pH value but not the T(1/2) (pretreatment temperature at which half enzymatic activity is observed) for PP(i) hydrolytic activity. Mutation of histidine residues obviously induced conformational changes of vacuolar H(+)-PPase as determined by immunoblotting analysis after limited trypsin digestion. Furthermore, mutation of these histidine residues modified the inhibitory effects of F(-) and Na(+), but not that of Ca(2+). Single substitution of H704, H716 and H758 by alanine partially released the effect of K(+) stimulation, indicating possible location of K(+) binding in the vicinity of domains surrounding these residues.
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Affiliation(s)
- Yi Y Hsiao
- Department of Life Sciences and Institute of Bioinformatics and Structural Biology, College of Life Sciences, National Tsing Hua University, Hsin Chu 30043, Taiwan, ROC
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32
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Gordon-Weeks R, Tong Y, Davies TGE, Leggewie G. Restricted spatial expression of a high-affinity phosphate transporter in potato roots. J Cell Sci 2003; 116:3135-44. [PMID: 12799416 DOI: 10.1242/jcs.00615] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphorus deficiency limits plant growth, and high-affinity phosphate transporters, of the Pht1 family, facilitate phosphate uptake and translocation. The family is subdivided into root specific, phosphate deprivation induced members and those also expressed in leaves. An antibody to StPT2, a potato root specific transporter, detected two bands (52 kDa and 30 kDa) on western blots of root plasma membrane extracts that were most intense in whole extracts from the root tip and slightly increased throughout the root in response to phosphate depletion. RT-PCR, using StPT2 specific primers, confirmed these findings. Low power confocal immunofluorescent images showed StPT2 expression mainly in the elongation zone at the root tip. By contrast, a vacuolar pyrophosphatase and a plasma membrane ATPase antibody labelled the whole root. High power images showed, by comparison with alpha-tubulin, cell wall and plasma membrane ATPase labelling, that StPT2 was in the epidermal plasma membrane and restricted to the apical surface. This is the first evidence of polar plasma membrane localisation of a plant nutrient transporter and is consistent with a role for StPT2 in phosphate capture and uptake.
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33
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Drozdowicz YM, Shaw M, Nishi M, Striepen B, Liwinski HA, Roos DS, Rea PA. Isolation and characterization of TgVP1, a type I vacuolar H+-translocating pyrophosphatase from Toxoplasma gondii. The dynamics of its subcellular localization and the cellular effects of a diphosphonate inhibitor. J Biol Chem 2003; 278:1075-85. [PMID: 12411435 DOI: 10.1074/jbc.m209436200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Here we report the isolation and characterization of a type I vacuolar-type H(+)-pyrophosphatase (V-PPase), TgVP1, from an apicomplexan, Toxoplasma gondii, a parasitic protist that is particularly amenable to molecular and genetic manipulation. The 816-amino acid TgVP1 polypeptide is 50% sequence-identical (65% similar) to the prototypical type I V-PPase from Arabidopsis thaliana, AVP1, and contains all the sequence motifs characteristic of this pump category. Unlike AVP1 and other known type I enzymes, however, TgVP1 contains a 74-residue N-terminal extension encompassing a 42-residue N-terminal signal peptide sequence, sufficient for targeting proteins to the secretory pathway of T. gondii. Providing that the coding sequence for the entire N-terminal extension is omitted from the plasmid, transformation of Saccharomyces cerevisiae with plasmid-borne TgVP1 yields a stable and functional translation product that is competent in aminomethylenediphosphonate (AMDP)-inhibitable K(+)-activated pyrophosphate (PP(i)) hydrolysis and PP(i)-energized H(+) translocation. Immunofluorescence microscopy of both free and intracellular T. gondii tachyzoites using purified universal V-PPase polyclonal antibodies reveals a punctate apical distribution for the enzyme. Equivalent studies of the tachyzoites during host cell invasion, by contrast, disclose a transverse radial distribution in which the V-PPase is associated with a collar-like structure that migrates along the length of the parasite in synchrony with and in close apposition to the penetration furrow. Although treatment of T. gondii with AMDP concentrations as high as 100 microm had no discernible effect on the efficiency of host cell invasion and integration, concentrations commensurate with the I(50) for the inhibition of TgVP1 activity in vitro (0.9 microm) do inhibit cell division and elicit nuclear enlargement concomitant with the inflation and eventual disintegration of acidocalcisome-like vesicular structures. A dynamic association of TgVP1 with the host cell invasion apparatus is invoked, one in which the effects of inhibitory V-PPase substrate analogs are exerted after rather than during host cell invasion.
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34
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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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35
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Belogurov GA, Turkina MV, Penttinen A, Huopalahti S, Baykov AA, Lahti R. H+-pyrophosphatase of Rhodospirillum rubrum. High yield expression in Escherichia coli and identification of the Cys residues responsible for inactivation my mersalyl. J Biol Chem 2002; 277:22209-14. [PMID: 11956221 DOI: 10.1074/jbc.m202951200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
H(+)-translocating pyrophosphatase (H(+)-PPase) of the photosynthetic bacterium Rhodospirillum rubrum was expressed in Escherichia coli C43(DE3) cells. Recombinant H(+)-PPase was observed in inner membrane vesicles, where it catalyzed both PP(i) hydrolysis coupled with H(+) transport into the vesicles and PP(i) synthesis. The hydrolytic activity of H(+)-PPase in E. coli vesicles was eight times greater than that in R. rubrum chromatophores but exhibited similar sensitivity to the H(+)-PPase inhibitor, aminomethylenediphosphonate, and insensitivity to the soluble PPase inhibitor, fluoride. Using this expression system, we showed that substitution of Cys(185), Cys(222), or Cys(573) with aliphatic residues had no effect on the activity of H(+)-PPase but decreased its sensitivity to the sulfhydryl modifying reagent, mersalyl. H(+)-PPase lacking all three Cys residues was completely resistant to the effects of mersalyl. Mg(2+) and MgPP(i) protected Cys(185) and Cys(573) from modification by this agent but not Cys(222). Phylogenetic analyses of 23 nonredundant H(+)-PPase sequences led to classification into two subfamilies. One subfamily invariably contains Cys(222) and includes all known K(+)-independent H(+)-PPases, whereas the other incorporates a conserved Cys(573) but lacks Cys(222) and includes all known K(+)-dependent H(+)-PPases. These data suggest a specific link between the incidence of Cys at positions 222 and 573 and the K(+) dependence of H(+)-PPase.
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Affiliation(s)
- Georgiy A Belogurov
- Department of Biochemistry and Food Chemistry, University of Turku, FIN-20014 Turku, Finland
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36
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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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37
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Hsiao YY, Van RC, Hung HH, Pan RL. Diethylpyrocarbonate inhibition of vacuolar H+-pyrophosphatase possibly involves a histidine residue. JOURNAL OF PROTEIN CHEMISTRY 2002; 21:51-8. [PMID: 11902667 DOI: 10.1023/a:1014183100021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Vacuolar proton pumping pyrophosphatase (H+-PPase; EC 3.6.1.1) plays a pivotal role in electrogenic translocation of protons from cytosol to the vacuolar lumen at the expense of PPi hydrolysis. A histidine-specific modifier, diethylpyrocarbonate (DEPC), could substantially inhibit enzymic activity and H+-translocation of vacuolar H+-PPase in a concentration-dependent manner. Absorbance of vacuolar H+-PPase at 240 nm was increased upon incubation with DEPC, demonstrating that an N-carbethoxyhistidine moiety was probably formed. On the other hand, hydroxylamine, a reagent that can deacylate N-carbethoxyhistidine, could reverse the absorption change at 240 nm and partially restore PPi hydrolysis activity as well. The pKa of modified residues of the enzyme was determined to be 6.4, a value close to that of histidine. Thus, we speculate that inhibition of vacuolar H+-PPase by DEPC possibly could be attributed to the modification of histidyl residues on the enzyme. Furthermore, inhibition of vacuolar H+-PPase by DEPC follows pseudo-first-order rate kinetics. A reaction order of 0.85 was calculated from a double logarithmic plot of the apparent reaction constant against DEPC concentration, suggesting that the modification of one single histidine residue on the enzyme suffices to inhibit vacuolar H+-PPase. Inhibition of vacuolar H+-PPase by DEPC changes Vmax but not Km values. Moreover, DEPC inhibition of vacuolar H+-PPase could be substantially protected against by its physiological substrate, Mg2+-PPi. These results indicated that DEPC specifically competes with the substrate at the active site and the DEPC-labeled histidine residue might locate in or near the catalytic domain of the enzyme. Besides, pretreatment of the enzyme with N-ethylmaleimide decreased the degree of subsequent labeling of H+-PPase by DEPC. Taken together, we suggest that vacuolar H+-PPase likely contains a substrate-protectable histidine residue contributing to the inhibition of its activity by DEPC, and this histidine residue may located in a domain sensitive to the modification of Cys-629 by NEM.
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Affiliation(s)
- Yi Yuong Hsiao
- Department of Life Science, College of Life Science, National Tsing Hua University, Hsin Chu, Taiwan, Republic of China
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38
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Hoja-Lukowicz D, Lityńska A, Wójczyk BS. Affinity chromatography of branched oligosaccharides in rat liver beta-glucuronidase. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2001; 755:173-83. [PMID: 11393703 DOI: 10.1016/s0378-4347(01)00057-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Rat liver microsomal and lysosomal beta-glucuronidase-derived glycopeptides were obtained by extensive Pronase digestion followed by N-[14C]acetylation and desialylation by neuraminidase treatment. These glycopeptides were studied by sequential chromatography on lectin-affinity columns such as concanavalin A, lentil lectin, Phaseolus vulgaris erythroagglutinin, Ricinus communis agglutinin I, Triticum vulgaris agglutinin, Glycine max agglutinin and Ulex europaeus agglutinin. Using serial lectin affinity chromatography approach combined with neuraminidase treatment allowed us to show the unexpected presence of complex tri- and/or tetraantennary type glycans (40.8 and 17.0% for microsomal and lysosomal enzyme, respectively). Moreover, the application of neuraminidase treatment revealed that complex biantennary type glycans, present on lysosomal beta-glucuronidase, are almost fully sialylated while the same type of glycans present on microsomal enzyme do not contain sialic acid. Furthermore, the results obtained confirmed that microsomal and lysosomal beta-glucuronidases possess high mannose and/or hybrid type glycans (19.6 and 36.6%, respectively), and complex biantennary type glycans (38.9 and 46.4%, respectively).
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Affiliation(s)
- D Hoja-Lukowicz
- Department of Animal Physiology, Institute of Zoology, Jagiellonian University, Kraków, Poland.
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39
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Liu G, Sánchez-Fernández R, Li ZS, Rea PA. Enhanced multispecificity of arabidopsis vacuolar multidrug resistance-associated protein-type ATP-binding cassette transporter, AtMRP2. J Biol Chem 2001; 276:8648-56. [PMID: 11115509 DOI: 10.1074/jbc.m009690200] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent investigations have established that Arabidopsis thaliana contains a family of genes encoding ATP-binding cassette transporters belonging to the multidrug resistance-associated protein (MRP) family. So named because of the phenotypes conferred by their animal prototypes, many MRPs are MgATP-energized pumps active in the transport of glutathione (GS) conjugates and other bulky amphipathic anions across membranes. Here we show that Arabidopsis MRP2 (AtMRP2) localizes to the vacuolar membrane fraction from seedlings and is not only competent in the transport of GS conjugates but also glucuronate conjugates after heterologous expression in yeast. Based on the stimulatory action of the model GS conjugate 2,4-dinitrophenyl-GS (DNP-GS) on uptake of the model glucuronide 17beta-estradiol 17-(beta-d-glucuronide) (E(2)17betaG) and vice versa, double-label experiments demonstrating that the two substrates are subject to simultaneous transport by AtMRP2 and preloading experiments suggesting that the effects seen result from cis, not trans, interactions, it is inferred that some GS conjugates and some glucuronides reciprocally activate each other's transport via distinct but coupled binding sites. The results of parallel experiments on AtMRP1 and representative yeast and mammalian MRPs indicate that these properties are specific to AtMRP2. The effects exerted by DNP-GS on AtMRP2 are not, however, common to all GS conjugates and not simulated by oxidized glutathione or reduced glutathione. Decyl-GS, metolachlor-GS, and oxidized glutathione, although competitive with DNP-GS, do not promote E(2)17betaG uptake by AtMRP2. Reduced glutathione, although subject to transport by AtMRP2 and able to markedly promote E(2)17betaG uptake, neither competes with DNP-GS for uptake nor is subject to E(2)17betaG-promoted uptake. A multisite model comprising three or four semi-autonomous transport pathways plus distinct but tightly coupled binding sites is invoked for AtMRP2.
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Affiliation(s)
- G Liu
- Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018, USA
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40
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Nakanishi Y, Saijo T, Wada Y, Maeshima M. Mutagenic analysis of functional residues in putative substrate-binding site and acidic domains of vacuolar H+-pyrophosphatase. J Biol Chem 2001; 276:7654-60. [PMID: 11113147 DOI: 10.1074/jbc.m009743200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vacuolar H(+)-translocating inorganic pyrophosphatase (V-PPase) uses PP(i) as an energy donor and requires free Mg(2+) for enzyme activity and stability. To determine the catalytic domain, we analyzed charged residues (Asp(253), Lys(261), Glu(263), Asp(279), Asp(283), Asp(287), Asp(723), Asp(727), and Asp(731)) in the putative PP(i)-binding site and two conserved acidic regions of mung bean V-PPase by site-directed mutagenesis and heterologous expression in yeast. Amino acid substitution of the residues with alanine and conservative residues resulted in a marked decrease in PP(i) hydrolysis activity and a complete loss of H(+) transport activity. The conformational change of V-PPase induced by the binding of the substrate was reflected in the susceptibility to trypsin. Wild-type V-PPase was completely digested by trypsin but not in the presence of Mg-PP(i), while two V-PPase mutants, K261A and E263A, became sensitive to trypsin even in the presence of the substrate. These results suggest that the second acidic region is also implicated in the substrate hydrolysis and that at least two residues, Lys(261) and Glu(263), are essential for the substrate-binding function. From the observation that the conservative mutants K261R and E263D showed partial activity of PP(i) hydrolysis but no proton pump activity, we estimated that two residues, Lys(261) and Glu(263), might be related to the energy conversion from PP(i) hydrolysis to H(+) transport. The importance of two residues, Asp(253) and Glu(263), in the Mg(2+)-binding function was also suggested from the trypsin susceptibility in the presence of Mg(2+). Furthermore, it was found that the two acidic regions include essential common motifs shared among the P-type ATPases.
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Affiliation(s)
- Y Nakanishi
- Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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41
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Yang SJ, Jiang SS, Van RC, Hsiao YY, Pan R. A lysine residue involved in the inhibition of vacuolar H(+)-pyrophosphatase by fluorescein 5'-isothiocyanate. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1460:375-83. [PMID: 11106777 DOI: 10.1016/s0005-2728(00)00203-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Vacuolar proton pumping pyrophosphatase (H(+)-PPase; EC 3.6.1.1) plays a central role in the electrogenic translocation of protons from cytosol to the vacuole lumen at the expense of PP(i) hydrolysis. A fluorescent probe, fluorescein 5'-isothiocyanate (FITC), was used to modify a lysine residue of vacuolar H(+)-PPase. The enzymatic activity and its associated H(+) translocation of vacuolar H(+)-PPase were markedly decreased by FITC in a concentration-dependent manner. The inhibition of enzymatic activity followed pseudo-first-order rate kinetics. A double-logarithmic plot of the apparent reaction rate constant against FITC concentration yielded a straight line with a slope of 0.89, suggesting that the alteration of a single lysine residue on the enzyme is sufficient to inhibit vacuolar H(+)-PPase. Changes in K(m) but not V(max) values of vacuolar H(+)-PPase as inhibited by FITC were obtained, indicating that the labeling caused a modification in affinity of the enzyme to its substrate. FITC inhibition of vacuolar H(+)-PPase could be protected by its physiological substrate, Mg(2+)-PP(i). These results indicate that FITC might specifically compete with the substrate at the active site and the FITC-labeled lysine residue locates probably in or near the catalytic domain of the enzyme. The enhancement of fluorescence intensity and the blue shift of the emission maximum of FITC after modification of vacuolar H(+)-PPase suggest that the FITC-labeled lysine residue is located in a relatively hydrophobic region.
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Affiliation(s)
- S J Yang
- Department of Radiological Technology, Chungtai Institute of Health Sciences and Technology, Taichung 40605, Taiwan, ROC
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42
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Hill JE, Scott DA, Luo S, Docampo R. Cloning and functional expression of a gene encoding a vacuolar-type proton-translocating pyrophosphatase from Trypanosoma cruzi. Biochem J 2000; 351:281-8. [PMID: 10998372 PMCID: PMC1221360 DOI: 10.1042/0264-6021:3510281] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Acidocalcisomes are acidic Ca(2+)-storage organelles found in trypanosomatids that are similar to organelles known historically as volutin granules. Acidification of these organelles is driven in part by a vacuolar H(+)-pyrophosphatase (V-H(+)-PPase), an enzyme that is also present in plant vacuoles and in some bacteria. Here, we report the cloning and sequencing of a gene encoding the acidocalcisomal V-H(+)-PPase of Trypanosoma cruzi. The protein (T. cruzi pyrophosphatase, TcPPase) predicted from the nucleotide sequence of the gene has 816 amino acids and a molecular mass of 85 kDa. Several sequence motifs found in plant V-H(+)-PPases were present in TcPPase, explaining its sensitivity to N-ethylmaleimide and N,N'-dicyclohexylcarbodi-imide. Heterologous expression of the cDNA encoding TcPPase in the yeast Saccharomyces cerevisiae produced a functional enzyme. Phylogenetic analysis of the available V-H(+)-PPase sequences indicates that TcPPase is nearer to the vascular plant cluster and the branch containing Chara, a precursor to land plants, than to any of the other pyrophosphatase sequences included in the analysis. The apparent lack of such a V-H(+)-PPase in mammalian cells may provide a target for the development of new drugs.
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Affiliation(s)
- J E Hill
- Laboratory of Molecular Parasitology, Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, IL 61802, USA
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Drozdowicz YM, Kissinger JC, Rea PA. AVP2, a sequence-divergent, K(+)-insensitive H(+)-translocating inorganic pyrophosphatase from Arabidopsis. PLANT PHYSIOLOGY 2000; 123:353-62. [PMID: 10806252 PMCID: PMC59009 DOI: 10.1104/pp.123.1.353] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/1999] [Accepted: 01/25/2000] [Indexed: 05/18/2023]
Abstract
Plant vacuolar H(+)-translocating inorganic pyrophosphatases (V-PPases; EC 3.6.1.1) have been considered to constitute a family of functionally and structurally monotonous intrinsic membrane proteins. Typified by AVP1 (V. Sarafian, Y. Kim, R.J. Poole, P.A. Rea [1992] Proc Natl Acad Sci USA 89: 1775-1779) from Arabidopsis, all characterized plant V-PPases share greater than 84% sequence identity and catalyze K(+)-stimulated H(+) translocation. Here we describe the molecular and biochemical characterization of AVP2 (accession no. AF182813), a sequence-divergent (36% identical) K(+)-insensitive, Ca(2+)-hypersensitive V-PPase active in both inorganic pyrophosphate hydrolysis and H(+) translocation. The differences between AVP2 and AVP1 provide the first indication that plant V-PPases from the same organism fall into two distinct categories. Phylogenetic analyses of these and other V-PPase sequences extend this principle by showing that AVP2, rather than being an isoform of AVP1, is but one representative of a novel category of AVP2-like (type II) V-PPases that coexist with AVP1-like (type I) V-PPases not only in plants, but also in apicomplexan protists such as the malarial parasite Plasmodium falciparum.
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Affiliation(s)
- Y M Drozdowicz
- Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia 19104-6018, USA
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Abstract
The H(+)-translocating inorganic pyrophosphatase (H(+)-PPase) is a unique, electrogenic proton pump distributed among most land plants, but only some alga, protozoa, bacteria, and archaebacteria. This enzyme is a fine model for research on the coupling mechanism between the pyrophosphate hydrolysis and the active proton transport, since the enzyme consists of a single polypeptide with a calculated molecular mass of 71-80 kDa and its substrate is also simple. Cloning of the H(+)-PPase genes from several organisms has revealed the conserved regions that may be the catalytic site and/or participate in the enzymatic function. The primary sequences are reviewed with reference to biochemical properties of the enzyme, such as the requirement of Mg(2)(+) and K(+). In plant cells, H(+)-PPase coexists with H(+)-ATPase in a single vacuolar membrane. The physiological significance and the regulation of the gene expression of H(+)-PPase are also reviewed.
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Affiliation(s)
- M Maeshima
- Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
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Hirata T, Nakamura N, Omote H, Wada Y, Futai M. Regulation and reversibility of vacuolar H(+)-ATPase. J Biol Chem 2000; 275:386-9. [PMID: 10617629 DOI: 10.1074/jbc.275.1.386] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Arabidopsis thaliana vacuolar H(+)-translocating pyrophosphatase (V-PPase) was expressed functionally in yeast vacuoles with endogenous vacuolar H(+)-ATPase (V-ATPase), and the regulation and reversibility of V-ATPase were studied using these vacuoles. Analysis of electrochemical proton gradient (DeltamuH) formation with ATP and pyrophosphate indicated that the proton transport by V-ATPase or V-PPase is not regulated strictly by the proton chemical gradient (DeltapH). On the other hand, vacuolar membranes may have a regulatory mechanism for maintaining a constant membrane potential (DeltaPsi). Chimeric vacuolar membranes showed ATP synthesis coupled with DeltamuH established by V-PPase. The ATP synthesis was sensitive to bafilomycin A(1) and exhibited two apparent K(m) values for ADP. These results indicate that V-ATPase is a reversible enzyme. The ATP synthesis was not observed in the presence of nigericin, which dissipates DeltapH but not DeltaPsi, suggesting that DeltapH is essential for ATP synthesis.
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Affiliation(s)
- T Hirata
- Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan
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46
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Islam MR, Waheed A, Shah GN, Tomatsu S, Sly WS. Human egasyn binds beta-glucuronidase but neither the esterase active site of egasyn nor the C terminus of beta-glucuronidase is involved in their interaction. Arch Biochem Biophys 1999; 372:53-61. [PMID: 10562416 DOI: 10.1006/abbi.1999.1449] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lysosomal beta-glucuronidase shows a dual localization in mouse liver, where a significant fraction is retained in the endoplasmic reticulum (ER) by interaction with an ER-resident carboxyl esterase called egasyn. This interaction of mouse egasyn (mEg) with murine beta-glucuronidase (mGUSB) involves binding of the C-terminal 8 residues of the mGUSB to the carboxylesterase active site of the mEg. We isolated the recombinant human homologue of the mouse egasyn cDNA and found that it too binds human beta-glucuronidase (hGUSB). However, the binding appears not to involve the active site of the human egasyn (hEg) and does not involve the C-terminal 18 amino acids of hGUSB. The full-length cDNA encoding hEg was isolated from a human liver cDNA library using full-length mEg cDNA as a probe. The 1941-bp cDNA differs by only a few bases from two previously reported cDNAs for human liver carboxylesterase, allowing the anti-human carboxylesterase antiserum to be used for immunoprecipitation of human egasyn. The cDNA expressed bis-p-nitrophenyl phosphate (BPNP)-inhibitable esterase activity in COS cells. When expressed in COS cells, it is localized to the ER. The intracellular hEg coimmunoprecipitated with full-length hGUSB and with a truncated hGUSB missing the C-terminal 18-amino-acid residue when extracts of COS cells expressing both proteins were treated with anti-hGUSB antibody. It did not coimmunoprecipitate with mGUSB from extracts of coexpressing COS cells. Unlike mEg, hEg was not released from the hEg-GUSB complex with BPNP. Thus, hEg resembles mEg in that it binds hGUSB. However, it differs from mEg in that (i) it does not appear to use the esterase active site for binding since treatment with BPNP did not release hEg from hGUSB and (ii) it does not use the C terminus of GUSB for binding, since a C-terminal truncated hGUSB (the C-terminal 18 amino acids are removed) bound as well as nontruncated hGUSB. Evidence is presented that an internal segment of 51 amino acids between 228 and 279 residues contributes to binding of hGUSB by hEg.
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Affiliation(s)
- M R Islam
- E. A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University Health Sciences Center, 1402 S. Grand Boulevard, St. Louis, Missouri, 63104, USA
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Drozdowicz YM, Lu YP, Patel V, Fitz-Gibbon S, Miller JH, Rea PA. A thermostable vacuolar-type membrane pyrophosphatase from the archaeon Pyrobaculum aerophilum: implications for the origins of pyrophosphate-energized pumps. FEBS Lett 1999; 460:505-12. [PMID: 10556526 DOI: 10.1016/s0014-5793(99)01404-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Vacuolar-type H(+)-translocating pyrophosphatases (V-PPases) have been considered to be restricted to plants, a few species of phototrophic proteobacteria and protists. Here, we describe PVP, a thermostable, sequence-divergent V-PPase from the facultatively aerobic hyperthermophilic archaeon Pyrobaculum aerophilum. PVP shares only 38% sequence identity with both the prototypical V-PPase from Arabidopsis thaliana and the H(+)-PPi synthase from Rhodospirillum rubrum, yet possesses most of the structural features characteristic of V-PPases. Heterologous expression of PVP in Saccharomyces cerevisiae yields a M(r) 64¿ omitted¿000 membrane polypeptide that specifically catalyzes Mg(2+)-dependent PPi hydrolysis. The existence of PVP implies that PPi-energized H(+)-translocation is phylogenetically more deeply rooted than previously thought.
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Affiliation(s)
- Y M Drozdowicz
- Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
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Nakanishi Y, Matsuda N, Aizawa K, Kashiyama T, Yamamoto K, Mimura T, Ikeda M, Maeshima M. Molecular cloning and sequencing of the cDNA for vacuolar H+-pyrophosphatase from Chara corallina1. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1418:245-50. [PMID: 10209229 DOI: 10.1016/s0005-2736(99)00037-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have cloned a cDNA for vacuolar proton-translocating pyrophosphatase of Chara corallina that is one of the closest green algae to the land plants. The deduced protein consists of 793 amino acid residues. Its sequence is 71% identical to the H+-pyrophosphatases of land plants, and is less than 46% identical to those of marine alga and phototrophic bacterium.
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Affiliation(s)
- Y Nakanishi
- Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Yang SJ, Ko SJ, Tsai YR, Jiang SS, Kuo SY, Hung SH, Pan RL. Subunit interaction of vacuolar H+-pyrophosphatase as determined by high hydrostatic pressure. Biochem J 1998; 331 ( Pt 2):395-402. [PMID: 9531476 PMCID: PMC1219367 DOI: 10.1042/bj3310395] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Vacuolar H+-pyrophosphatase (H+-PPase) from etiolated hypocotyls of mung bean (Vigna radiata L.) is a homodimer with a molecular mass of 145 kDa. The vacuolar H+-PPase was subjected to high hydrostatic pressure to investigate its structure and function. The inhibition of H+-PPase activity by high hydrostatic pressure has a pressure-, time- and protein-concentration-dependent manner. The Vmax value of vacuolar H+-PPase was dramatically decreased by pressurization from 293.9 to 70.2 micromol of PPi (pyrophosphate) consumed/h per mg of protein, while the Km value decreased from 0.35 to 0.08 mM, implying that the pressure treatment increased the affinity of PPi to vacuolar H+-PPase but decreased its hydrolysis. The physiological substrate and its analogues enhance high pressure inhibition of vacuolar H+-PPase. The HPLC profile reveals high pressure treatment of H+-PPase provokes the subunit dissociation from an active into inactive form. High hydrostatic pressure also induces the conformational change of vacuolar H+-PPase as determined by spectroscopic techniques. Our results indicate the importance of protein-protein interaction for this novel proton-translocating enzyme. Working models are proposed to interpret the pressure inactivation of vacuolar H+-PPase. We also suggest that association of identical subunits of vacuolar H+-PPase is not random but proceeds in a specific manner.
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Affiliation(s)
- S J Yang
- Institute of Radiation Biology, College of Nuclear Science, National Tsing Hua University, Hsin Chu 30043, Taiwan, Republic of China
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50
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Nakanishi Y, Maeshima M. Molecular cloning of vacuolar H(+)-pyrophosphatase and its developmental expression in growing hypocotyl of mung bean. PLANT PHYSIOLOGY 1998; 116:589-97. [PMID: 9489011 PMCID: PMC35116 DOI: 10.1104/pp.116.2.589] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/1997] [Accepted: 10/27/1997] [Indexed: 05/18/2023]
Abstract
Vacuolar proton-translocating inorganic pyrophosphatase and H(+)-ATPase acidify the vacuoles and power the vacuolar secondary active transport systems in plants. Developmental changes in the transcription of the pyrophosphatase in growing hypocotyls of mung bean (Vigna radiata) were investigated. The cDNA clone for the mung bean enzyme contains an uninterrupted open reading frame of 2298 bp, coding for a polypeptide of 766 amino acids. Hypocotyls were divided into elongating and mature regions. RNA analysis revealed that the transcript level of the pyrophosphatase was high in the elongating region of the 3-d-old hypocotyl but was extremely low in the mature region of the 5-d-old hypocotyl. The level of transcript of the 68-kD subunit of H(+)-ATPase also decreased after cell maturation. In the elongating region, the proton-pumping activity of pyrophosphatase on the basis of membrane protein was 3 times higher than that of H(+)-ATPase. After cell maturation, the pyrophosphatase activity decreased to 30% of that in the elongating region. The decline in the pyrophosphatase activity was in parallel with a decrease in the enzyme protein content. These findings indicate that the level of the pyrophosphatase, a main vacuolar proton pump in growing cells, is negatively regulated after cell maturation at the transcriptional level.
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Affiliation(s)
- Y Nakanishi
- Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Japan
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