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Sato N, Endo M, Nishi H, Fujiwara S, Tsuzuki M. Polyphosphate-kinase-1 dependent polyphosphate hyperaccumulation for acclimation to nutrient loss in the cyanobacterium, Synechocystis sp. PCC 6803. FRONTIERS IN PLANT SCIENCE 2024; 15:1441626. [PMID: 39145186 PMCID: PMC11322815 DOI: 10.3389/fpls.2024.1441626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Accepted: 07/15/2024] [Indexed: 08/16/2024]
Abstract
Polyphosphate is prevalent in living organisms. To obtain insights into polyphosphate synthesis and its physiological significance in cyanobacteria, we characterize sll0290, a homolog of the polyphosphate-kinase-1 gene, in the freshwater cyanobacterium Synechocystis sp. PCC 6803. The Sll0290 protein structure reveals characteristics of Ppk1. A Synechocystis sll0290 disruptant and sll0290-overexpressing Escherichia coli transformant demonstrated loss and gain of polyphosphate synthesis ability, respectively. Accordingly, sll0290 is identified as ppk1. The disruptant (Δppk1) grows normally with aeration of ordinary air (0.04% CO2), consistent with its photosynthesis comparable to the wild type level, which contrasts with a previously reported high-CO2 (5%) requirement for Δppk1 in an alkaline hot spring cyanobacterium, Synechococcus OS-B'. Synechocystis Δppk1 is defective in polyphosphate hyperaccumulation and survival competence at the stationary phase, and also under sulfur-starvation conditions, implying that sulfur limitation is one of the triggers to induce polyphosphate hyperaccumulation in stationary cells. Furthermore, Δppk1 is defective in the enhancement of total phosphorus contents under sulfur-starvation conditions, a phenomenon that is only partially explained by polyphosphate hyperaccumulation. This study therefore demonstrates that in Synechocystis, ppk1 is not essential for low-CO2 acclimation but plays a crucial role in dynamic P-metabolic regulation, including polyP hyperaccumulation, to maintain physiological fitness under sulfur-starvation conditions.
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Affiliation(s)
- Norihiro Sato
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
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2
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Guan J, Jakob U. The Protein Scaffolding Functions of Polyphosphate. J Mol Biol 2024; 436:168504. [PMID: 38423453 DOI: 10.1016/j.jmb.2024.168504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/31/2024] [Accepted: 02/21/2024] [Indexed: 03/02/2024]
Abstract
Inorganic polyphosphate (polyP), one of the first high-energy compound on earth, defies its extreme compositional and structural simplicity with an astoundingly wide array of biological activities across all domains of life. However, the underlying mechanism of such functional pleiotropy remains largely elusive. In this review, we will summarize recent studies demonstrating that this simple polyanion stabilizes protein folding intermediates and scaffolds select native proteins. These functions allow polyP to act as molecular chaperone that protects cells against protein aggregation, as pro-amyloidogenic factor that accelerates both physiological and disease-associated amyloid formation, and as a modulator of liquid-liquid phase separation processes. These activities help to explain polyP's known roles in bacterial stress responses and pathogenicity, provide the mechanistic foundation for its potential role in human neurodegenerative diseases, and open a new direction regarding its influence on gene expression through condensate formation. We will highlight critical unanswered questions and point out potential directions that will help to further understand the pleiotropic functions of this ancient and ubiquitous biopolymer.
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Affiliation(s)
- Jian Guan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Ursula Jakob
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA; Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI, USA.
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3
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Khan A, Mallick M, Ladke JS, Bhandari R. The ring rules the chain - inositol pyrophosphates and the regulation of inorganic polyphosphate. Biochem Soc Trans 2024; 52:567-580. [PMID: 38629621 DOI: 10.1042/bst20230256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 03/29/2024] [Accepted: 04/03/2024] [Indexed: 04/25/2024]
Abstract
The maintenance of phosphate homeostasis serves as a foundation for energy metabolism and signal transduction processes in all living organisms. Inositol pyrophosphates (PP-InsPs), composed of an inositol ring decorated with monophosphate and diphosphate moieties, and inorganic polyphosphate (polyP), chains of orthophosphate residues linked by phosphoanhydride bonds, are energy-rich biomolecules that play critical roles in phosphate homeostasis. There is a complex interplay between these two phosphate-rich molecules, and they share an interdependent relationship with cellular adenosine triphosphate (ATP) and inorganic phosphate (Pi). In eukaryotes, the enzymes involved in PP-InsP synthesis show some degree of conservation across species, whereas distinct enzymology exists for polyP synthesis among different organisms. In fact, the mechanism of polyP synthesis in metazoans, including mammals, is still unclear. Early studies on PP-InsP and polyP synthesis were conducted in the slime mould Dictyostelium discoideum, but it is in the budding yeast Saccharomyces cerevisiae that a clear understanding of the interplay between polyP, PP-InsPs, and Pi homeostasis has now been established. Recent research has shed more light on the influence of PP-InsPs on polyP in mammals, and the regulation of both these molecules by cellular ATP and Pi levels. In this review we will discuss the cross-talk between PP-InsPs, polyP, ATP, and Pi in the context of budding yeast, slime mould, and mammals. We will also highlight the similarities and differences in the relationship between these phosphate-rich biomolecules among this group of organisms.
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Affiliation(s)
- Azmi Khan
- Laboratory of Cell Signalling, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
| | - Manisha Mallick
- Laboratory of Cell Signalling, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
- Graduate Studies, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Jayashree S Ladke
- Laboratory of Cell Signalling, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
- Graduate Studies, Regional Centre for Biotechnology, Faridabad 121001, Haryana, India
| | - Rashna Bhandari
- Laboratory of Cell Signalling, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
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An Autocrine Negative Feedback Loop Inhibits Dictyostelium discoideum Proliferation through Pathways Including IP3/Ca 2. mBio 2021; 12:e0134721. [PMID: 34154396 PMCID: PMC8262924 DOI: 10.1128/mbio.01347-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Little is known about how eukaryotic cells can sense their number or spatial density and stop proliferating when the local density reaches a set value. We previously found that Dictyostelium discoideum accumulates extracellular polyphosphate to inhibit its proliferation, and this requires the G protein-coupled receptor GrlD and the small GTPase RasC. Here, we show that cells lacking the G protein component Gβ, the Ras guanine nucleotide exchange factor GefA, phosphatase and tensin homolog (PTEN), phospholipase C (PLC), inositol 1,4,5-trisphosphate (IP3) receptor-like protein A (IplA), polyphosphate kinase 1 (Ppk1), or the TOR complex 2 component PiaA have significantly reduced sensitivity to polyphosphate-induced proliferation inhibition. Polyphosphate upregulates IP3, and this requires GrlD, GefA, PTEN, PLC, and PiaA. Polyphosphate also upregulates cytosolic Ca2+, and this requires GrlD, Gβ, GefA, RasC, PLC, IplA, Ppk1, and PiaA. Together, these data suggest that polyphosphate uses signal transduction pathways including IP3/Ca2+ to inhibit the proliferation of D. discoideum. IMPORTANCE Many mammalian tissues such as the liver have the remarkable ability to regulate their size and have their cells stop proliferating when the tissue reaches the correct size. One possible mechanism involves the cells secreting a signal that they all sense, and a high level of the signal tells the cells that there are enough of them and to stop proliferating. Although regulating such mechanisms could be useful to regulate tissue size to control cancer or birth defects, little is known about such systems. Here, we use a microbial system to study such a mechanism, and we find that key elements of the mechanism have similarities to human proteins. This then suggests the possibility that we may eventually be able to regulate the proliferation of selected cell types in humans and animals.
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Inorganic Polyphosphate in Host and Microbe Biology. Trends Microbiol 2021; 29:1013-1023. [PMID: 33632603 DOI: 10.1016/j.tim.2021.02.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/15/2022]
Abstract
Inorganic polyphosphate (polyP) is produced by both bacteria and their eukaryotic hosts, and it appears to play multiple important roles in the interactions between those organisms. However, the detailed mechanisms of how polyP synthesis is regulated in bacteria, and how it influences both bacterial and host biology, remain largely unexplored. In this review, we examine recent developments in the understanding of how bacteria regulate the synthesis of polyP, what roles polyP plays in controlling virulence in pathogenic bacteria, and the effects of polyP on the mammalian immune system, as well as progress on developing drugs that may be able to target bacterial polyP synthesis as novel means of treating infectious disease.
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Denoncourt A, Downey M. Model systems for studying polyphosphate biology: a focus on microorganisms. Curr Genet 2021; 67:331-346. [PMID: 33420907 DOI: 10.1007/s00294-020-01148-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 12/08/2020] [Accepted: 12/14/2020] [Indexed: 12/19/2022]
Abstract
Polyphosphates (polyP) are polymers of inorganic phosphates joined by high-energy bonds to form long chains. These chains are present in all forms of life but were once disregarded as 'molecular fossils'. PolyP has gained attention in recent years following new links to diverse biological roles ranging from energy storage to cell signaling. PolyP research in humans and other higher eukaryotes is limited by a lack of suitable tools and awaits the identification of enzymatic players that would enable more comprehensive studies. Therefore, many of the most important insights have come from single-cell model systems. Here, we review determinants of polyP metabolism, regulation, and function in major microbial systems, including bacteria, fungi, protozoa, and algae. We highlight key similarities and differences that may aid in our understanding of how polyP impacts cell physiology at a molecular level.
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Affiliation(s)
- Alix Denoncourt
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, K1H 8M5, Canada.,Ottawa Institute of Systems Biology, Ottawa, K1H 8M5, Canada
| | - Michael Downey
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, K1H 8M5, Canada. .,Ottawa Institute of Systems Biology, Ottawa, K1H 8M5, Canada.
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Suess PM, Smith SA, Morrissey JH. Platelet polyphosphate induces fibroblast chemotaxis and myofibroblast differentiation. J Thromb Haemost 2020; 18:3043-3052. [PMID: 32808449 PMCID: PMC7719587 DOI: 10.1111/jth.15066] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 08/11/2020] [Accepted: 08/14/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND Platelets secrete many pro-wound healing molecules such as growth factors and cytokines. We found that releasates from activated human platelets induced the differentiation of cultured murine and human fibroblasts into a myofibroblast phenotype. Surprisingly, most of this differentiation-inducing activity was heat-stable, suggesting it was not due to the protein component of the releasates. Inorganic polyphosphate is a major constituent of platelet-dense granules and promotes blood coagulation and inflammation. OBJECTIVES We aim to investigate the contribution of polyphosphate on myofibroblast differentiating activity of platelet releasates. METHODS Using NIH-3T3 cells and primary human fibroblasts, we examined the effect of human platelet releasates and chemically synthesized polyphosphate on fibroblast differentiation and migration. RESULTS We found that the myofibroblast-inducing activity of platelet releasates was severely attenuated after incubation with a polyphosphate-degrading enzyme, and that fibroblasts responded to platelet-sized polyphosphate by increased levels of α-smooth muscle actin, stress fibers, and collagen. Furthermore, fibroblasts were chemotactic toward polyphosphate. CONCLUSIONS These findings indicate that platelet-derived polyphosphate acts as a cell signaling molecule by inducing murine and human fibroblasts to differentiate into myofibroblasts, a cell type known to drive both wound healing and fibrosing diseases. Polyphosphate therefore not only promotes early wound responses through enhancing fibrin clot formation, but also may play roles in the later stages of wound healing, and, potentially, progression of fibrotic diseases, by recruiting fibroblasts and inducing their differentiation into myofibroblasts.
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Affiliation(s)
- Patrick M. Suess
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI
| | - Stephanie A. Smith
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI
| | - James H. Morrissey
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI
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Aoki MM, Emery RJN, Anjard C, Brunetti CR, Huber RJ. Cytokinins in Dictyostelia - A Unique Model for Studying the Functions of Signaling Agents From Species to Kingdoms. Front Cell Dev Biol 2020; 8:511. [PMID: 32714926 PMCID: PMC7316887 DOI: 10.3389/fcell.2020.00511] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 05/28/2020] [Indexed: 02/06/2023] Open
Abstract
Cytokinins (CKs) are a diverse group of evolutionarily significant growth-regulating molecules. While the CK biosynthesis and signal transduction pathways are the most well-understood in plant systems, these molecules have been identified in all kingdoms of life. This review follows the recent discovery of an expanded CK profile in the social amoeba, Dictyostelium discoideum. A comprehensive review on the present knowledge of CK biosynthesis, signal transduction, and CK-small molecule interactions within members of Dictyostelia will be summarized. In doing so, the utility of social amoebae will be highlighted as a model system for studying the evolution of these hormone-like signaling agents, which will set the stage for future research in this area.
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Affiliation(s)
- Megan M Aoki
- Department of Biology, Trent University, Peterborough, ON, Canada
| | - R J Neil Emery
- Department of Biology, Trent University, Peterborough, ON, Canada
| | - Christophe Anjard
- Institut Lumière Matière, CNRS UMR 5306, Université Claude Bernard Lyon 1, Université de Lyon, Lyon, France
| | - Craig R Brunetti
- Department of Biology, Trent University, Peterborough, ON, Canada
| | - Robert J Huber
- Department of Biology, Trent University, Peterborough, ON, Canada
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Zhu J, Loubéry S, Broger L, Zhang Y, Lorenzo-Orts L, Utz-Pugin A, Fernie AR, Young-Tae C, Hothorn M. A genetically validated approach for detecting inorganic polyphosphates in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:507-516. [PMID: 31816134 DOI: 10.1111/tpj.14642] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 11/08/2019] [Accepted: 12/03/2019] [Indexed: 06/10/2023]
Abstract
Inorganic polyphosphates (polyPs) are linear polymers of orthophosphate units linked by phosphoanhydride bonds. Polyphosphates represent important stores of phosphate and energy, and are abundant in many pro- and eukaryotic organisms. In plants, the existence of polyPs has been established using microscopy and biochemical extraction methods that are now known to produce artifacts. Here we use a polyP-specific dye and a polyP-binding domain to detect polyPs in plant and algal cells. To develop the staining protocol, we induced polyP granules in Nicotiana benthamiana and Arabidopsis cells by heterologous expression of Escherichia coli polyphosphate kinase 1 (PPK1). Over-expression of PPK1 but not of a catalytically impaired version of the enzyme leads to severe growth phenotypes, suggesting that ATP-dependent synthesis and accumulation of polyPs in the plant cytosol is toxic. We next crossed stable PPK1-expressing Arabidopsis lines with plants expressing the polyP-binding domain of E. coli exopolyphosphatase (PPX1c), which co-localized with PPK1-generated polyP granules. These granules were stained by the polyP-specific dye JC-D7 and appeared as electron-dense structures in transmission electron microscopy sections. Using the polyP staining protocol derived from these experiments, we screened for polyP stores in different organs and tissues of both mono- and dicotyledonous plants. While we could not detect polyP granules in higher plants, we could visualize the polyP-rich acidocalcisomes in the green alga Chlamydomonas reinhardtii.
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Affiliation(s)
- Jinsheng Zhu
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Sylvain Loubéry
- Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Larissa Broger
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Youjun Zhang
- Max-Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm, 14476, Germany
- Center of Plant System Biology and Biotechnology, Ruski Blvd. 139, Plovdiv, 4000, Bulgaria
| | - Laura Lorenzo-Orts
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Anne Utz-Pugin
- Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Alisdair R Fernie
- Max-Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm, 14476, Germany
| | - Chang Young-Tae
- Center for Self-assembly and Complexity, IBS and Department of Chemistry, POSTECH, 50, Jigok-ro 127beon-gil, Nam-gu, Pohang-si, Gyeongsangbuk-do, Pohang, 37673, Republic of Korea
| | - Michael Hothorn
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
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10
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Zhu J, Loubéry S, Broger L, Zhang Y, Lorenzo-Orts L, Utz-Pugin A, Fernie AR, Young-Tae C, Hothorn M. A genetically validated approach for detecting inorganic polyphosphates in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:507-516. [PMID: 31816134 DOI: 10.1101/630129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 11/08/2019] [Accepted: 12/03/2019] [Indexed: 05/22/2023]
Abstract
Inorganic polyphosphates (polyPs) are linear polymers of orthophosphate units linked by phosphoanhydride bonds. Polyphosphates represent important stores of phosphate and energy, and are abundant in many pro- and eukaryotic organisms. In plants, the existence of polyPs has been established using microscopy and biochemical extraction methods that are now known to produce artifacts. Here we use a polyP-specific dye and a polyP-binding domain to detect polyPs in plant and algal cells. To develop the staining protocol, we induced polyP granules in Nicotiana benthamiana and Arabidopsis cells by heterologous expression of Escherichia coli polyphosphate kinase 1 (PPK1). Over-expression of PPK1 but not of a catalytically impaired version of the enzyme leads to severe growth phenotypes, suggesting that ATP-dependent synthesis and accumulation of polyPs in the plant cytosol is toxic. We next crossed stable PPK1-expressing Arabidopsis lines with plants expressing the polyP-binding domain of E. coli exopolyphosphatase (PPX1c), which co-localized with PPK1-generated polyP granules. These granules were stained by the polyP-specific dye JC-D7 and appeared as electron-dense structures in transmission electron microscopy sections. Using the polyP staining protocol derived from these experiments, we screened for polyP stores in different organs and tissues of both mono- and dicotyledonous plants. While we could not detect polyP granules in higher plants, we could visualize the polyP-rich acidocalcisomes in the green alga Chlamydomonas reinhardtii.
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Affiliation(s)
- Jinsheng Zhu
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Sylvain Loubéry
- Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Larissa Broger
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Youjun Zhang
- Max-Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm, 14476, Germany
- Center of Plant System Biology and Biotechnology, Ruski Blvd. 139, Plovdiv, 4000, Bulgaria
| | - Laura Lorenzo-Orts
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Anne Utz-Pugin
- Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
| | - Alisdair R Fernie
- Max-Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm, 14476, Germany
| | - Chang Young-Tae
- Center for Self-assembly and Complexity, IBS and Department of Chemistry, POSTECH, 50, Jigok-ro 127beon-gil, Nam-gu, Pohang-si, Gyeongsangbuk-do, Pohang, 37673, Republic of Korea
| | - Michael Hothorn
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 30 Quai E. Ansermet, Geneva, 1211, Switzerland
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Inorganic polyphosphate in mammals: where's Wally? Biochem Soc Trans 2020; 48:95-101. [PMID: 32049314 PMCID: PMC7054745 DOI: 10.1042/bst20190328] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/30/2022]
Abstract
Inorganic polyphosphate (polyP) is a ubiquitous polymer of tens to hundreds of orthophosphate residues linked by high-energy phosphoanhydride bonds. In prokaryotes and lower eukaryotes, both the presence of polyP and of the biosynthetic pathway that leads to its synthesis are well-documented. However, in mammals, polyP is more elusive. Firstly, the mammalian enzyme responsible for the synthesis of this linear biopolymer is unknown. Secondly, the low sensitivity and specificity of available polyP detection methods make it difficult to confidently ascertain polyP presence in mammalian cells, since in higher eukaryotes, polyP exists in lower amounts than in yeast or bacteria. Despite this, polyP has been given a remarkably large number of functions in mammals. In this review, we discuss some of the proposed functions of polyP in mammals, the limitations of the current detection methods and the urgent need to understand how this polymer is synthesized.
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12
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Azevedo C, Desfougères Y, Jiramongkol Y, Partington H, Trakansuebkul S, Singh J, Steck N, Jessen HJ, Saiardi A. Development of a yeast model to study the contribution of vacuolar polyphosphate metabolism to lysine polyphosphorylation. J Biol Chem 2020; 295:1439-1451. [PMID: 31844018 PMCID: PMC7008358 DOI: 10.1074/jbc.ra119.011680] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/11/2019] [Indexed: 12/13/2022] Open
Abstract
A recently-discovered protein post-translational modification, lysine polyphosphorylation (K-PPn), consists of the covalent attachment of inorganic polyphosphate (polyP) to lysine residues. The nonenzymatic nature of K-PPn means that the degree of this modification depends on both polyP abundance and the amino acids surrounding the modified lysine. K-PPn was originally discovered in budding yeast (Saccharomyces cerevisiae), in which polyP anabolism and catabolism are well-characterized. However, yeast vacuoles accumulate large amounts of polyP, and upon cell lysis, the release of the vacuolar polyP could nonphysiologically cause K-PPn of nuclear and cytosolic targets. Moreover, yeast vacuoles possess two very active endopolyphosphatases, Ppn1 and Ppn2, that could have opposing effects on the extent of K-PPn. Here, we characterized the contribution of vacuolar polyP metabolism to K-PPn of two yeast proteins, Top1 (DNA topoisomerase 1) and Nsr1 (nuclear signal recognition 1). We discovered that whereas Top1-targeting K-PPn is only marginally affected by vacuolar polyP metabolism, Nsr1-targeting K-PPn is highly sensitive to the release of polyP and of endopolyphosphatases from the vacuole. Therefore, to better study K-PPn of cytosolic and nuclear targets, we constructed a yeast strain devoid of vacuolar polyP by targeting the exopolyphosphatase Ppx1 to the vacuole and concomitantly depleting the two endopolyphosphatases (ppn1Δppn2Δ, vt-Ppx1). This strain enabled us to study K-PPn of cytosolic and nuclear targets without the interfering effects of cell lysis on vacuole polyP and of endopolyphosphatases. Furthermore, we also define the fundamental nature of the acidic amino acid residues to the K-PPn target domain.
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Affiliation(s)
- Cristina Azevedo
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom.
| | - Yann Desfougères
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Yannasittha Jiramongkol
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Hamish Partington
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Sasanan Trakansuebkul
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Jyoti Singh
- Institute of Organic Chemistry, University of Freiburg, 79104 Freiburg, Germany
| | - Nicole Steck
- Institute of Organic Chemistry, University of Freiburg, 79104 Freiburg, Germany
| | - Henning J Jessen
- Institute of Organic Chemistry, University of Freiburg, 79104 Freiburg, Germany; CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Adolfo Saiardi
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom.
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Lorenzo‐Orts L, Couto D, Hothorn M. Identity and functions of inorganic and inositol polyphosphates in plants. THE NEW PHYTOLOGIST 2020; 225:637-652. [PMID: 31423587 PMCID: PMC6973038 DOI: 10.1111/nph.16129] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/22/2019] [Indexed: 05/08/2023]
Abstract
Inorganic polyphosphates (polyPs) and inositol pyrophosphates (PP-InsPs) form important stores of inorganic phosphate and can act as energy metabolites and signaling molecules. Here we review our current understanding of polyP and inositol phosphate (InsP) metabolism and physiology in plants. We outline methods for polyP and InsP detection, discuss the known plant enzymes involved in their synthesis and breakdown, and summarize the potential physiological and signaling functions for these enigmatic molecules in plants.
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Affiliation(s)
- Laura Lorenzo‐Orts
- Structural Plant Biology LaboratoryDepartment of Botany and Plant BiologyUniversity of Geneva30 Quai E. AnsermetGeneva1211Switzerland
| | - Daniel Couto
- Structural Plant Biology LaboratoryDepartment of Botany and Plant BiologyUniversity of Geneva30 Quai E. AnsermetGeneva1211Switzerland
| | - Michael Hothorn
- Structural Plant Biology LaboratoryDepartment of Botany and Plant BiologyUniversity of Geneva30 Quai E. AnsermetGeneva1211Switzerland
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Santarriaga S, Fikejs A, Scaglione J, Scaglione KM. A Heat Shock Protein 48 (HSP48) Biomolecular Condensate Is Induced during Dictyostelium discoideum Development. mSphere 2019; 4:e00314-19. [PMID: 31217303 PMCID: PMC6584373 DOI: 10.1128/msphere.00314-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 06/04/2019] [Indexed: 11/20/2022] Open
Abstract
The social amoeba Dictyostelium discoideum's proteome contains a vast array of simple sequence repeats, providing a unique model to investigate proteostasis. Upon conditions of cellular stress, D. discoideum undergoes a developmental process, transitioning from a unicellular amoeba to a multicellular fruiting body. Little is known about how proteostasis is maintained during D. discoideum's developmental process. Here, we have identified a novel α-crystallin domain-containing protein, heat shock protein 48 (HSP48), that is upregulated during D. discoideum development. HSP48 functions in part by forming a biomolecular condensate via its highly positively charged intrinsically disordered carboxy terminus. In addition to HSP48, the highly negatively charged primordial chaperone polyphosphate is also upregulated during D. discoideum development, and polyphosphate functions to stabilize HSP48. Upon germination, levels of both HSP48 and polyphosphate dramatically decrease, consistent with a role for HSP48 and polyphosphate during development. Together, our data demonstrate that HSP48 is strongly induced during Dictyostelium discoideum development. We also demonstrate that HSP48 forms a biomolecular condensate and that polyphosphate is necessary to stabilize the HSP48 biomolecular condensate.IMPORTANCE During cellular stress, many microbes undergo a transition to a dormant state. This includes the social amoeba Dictyostelium discoideum that transitions from a unicellular amoeba to a multicellular fruiting body upon starvation. In this work, we identify heat shock protein 48 (HSP48) as a chaperone that is induced during development. We also show that HSP48 forms a biomolecular condensate and is stabilized by polyphosphate. The findings here identify Dictyostelium discoideum as a novel microbe to investigate protein quality control pathways during the transition to dormancy.
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Affiliation(s)
| | - Alicia Fikejs
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Jamie Scaglione
- Department of Computational and Physical Sciences, Carroll University, Waukesha, Wisconsin, USA
| | - K Matthew Scaglione
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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15
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Mailer RKW, Hänel L, Allende M, Renné T. Polyphosphate as a Target for Interference With Inflammation and Thrombosis. Front Med (Lausanne) 2019; 6:76. [PMID: 31106204 PMCID: PMC6499166 DOI: 10.3389/fmed.2019.00076] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/28/2019] [Indexed: 12/19/2022] Open
Abstract
Activated platelets and mast cells expose the inorganic polymer, polyphosphate (polyP) on their surfaces. PolyP initiates procoagulant and proinflammatory reactions and the polymer has been recognized as a therapeutic target for interference with blood coagulation and vascular hyperpermeability. PolyP content and chain length depend on the specific cell type and energy status, which may affect cellular functions. PolyP metabolism has mainly been studied in bacteria and yeast, but its roles in eukaryotic cells and mammalian systems have remained enigmatic. In this review, we will present an overview of polyP functions, focusing on intra- and extracellular roles of the polymer and discuss open questions that emerge from the current knowledge on polyP regulation.
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Affiliation(s)
- Reiner K W Mailer
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Lorena Hänel
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Mikel Allende
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas Renné
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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16
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Abstract
Polyphosphate (polyP) consists of a linear arrangement of inorganic phosphates and defies its structural simplicity with an astounding number of different activities in the cell. Already well known for its ability to partake in phosphate, calcium, and energy metabolism, polyP recently gained a new functional dimension with the discovery that it serves as a stabilizing scaffold for protein-folding intermediates. In this review, we summarize and discuss the recent studies that have identified polyP not only as a potent protein-like chaperone that protects cells against stress-induced protein aggregation, but also as a robust modifier of amyloidogenic processes that shields neuronal cells from amyloid toxicity. We consider some of the most pressing questions in the field, the obstacles faced, and the potential avenues to take to provide a complete picture about the working mechanism and physiological relevance of this intriguing biopolymer.
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Affiliation(s)
- Lihan Xie
- From the Departments of Molecular, Cellular and Developmental Biology and
| | - Ursula Jakob
- From the Departments of Molecular, Cellular and Developmental Biology and
- Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1085
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17
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Long-chain polyphosphate in osteoblast matrix vesicles: Enrichment and inhibition of mineralization. Biochim Biophys Acta Gen Subj 2018; 1863:199-209. [PMID: 30312769 DOI: 10.1016/j.bbagen.2018.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 09/24/2018] [Accepted: 10/05/2018] [Indexed: 01/17/2023]
Abstract
BACKGROUND Inorganic polyphosphate (polyP) is a fundamental and ubiquitous molecule in prokaryotes and eukaryotes. PolyP has been found in mammalian tissues with particularly high levels of long-chain polyP in bone and cartilage where critical questions remain as to its localization and function. Here, we investigated polyP presence and function in osteoblast-like SaOS-2 cells and cell-derived matrix vesicles (MVs), the initial sites of bone mineral formation. METHODS PolyP was quantified by 4',6-diamidino-2-phenylindole (DAPI) fluorescence and characterized by enzymatic methods coupled to urea polyacrylamide gel electrophoresis. Transmission electron microscopy and confocal microscopy were used to investigate polyP localization. A chicken embryo cartilage model was used to investigate the effect of polyP on mineralization. RESULTS PolyP increased in concentration as SaOS-2 cells matured and mineralized. Particularly high levels of polyP were observed in MVs. The average length of MV polyP was determined to be longer than 196 Pi residues by gel chromatography. Electron micrographs of MVs, stained by two polyP-specific staining approaches, revealed polyP localization in the vicinity of the MV membrane. Additional extracellular polyP binds to MVs and inhibits MV-induced hydroxyapatite formation. CONCLUSION PolyP is highly enriched in matrix vesicles and can inhibit apatite formation. PolyP may be hydrolysed to phosphate for further mineralization in the extracellular matrix. GENERAL SIGNIFICANCE PolyP is a unique yet underappreciated macromolecule which plays a critical role in extracellular mineralization in matrix vesicles.
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18
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Cruz CS, Costa EP, Machado JA, Silva JN, Romeiro NC, Moraes J, Silva JR, Fonseca RN, Vaz IS, Logullo C, Campos E. A soluble inorganic pyrophosphatase from the cattle tick Rhipicephalus microplus capable of hydrolysing polyphosphates. INSECT MOLECULAR BIOLOGY 2018; 27:260-267. [PMID: 29271528 DOI: 10.1111/imb.12369] [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] [Indexed: 06/07/2023]
Abstract
Polyphosphates have been found in all cell types examined to date and play diverse roles depending on the cell type. In eukaryotic organisms, polyphosphates have been investigated mainly in mammalian cells, and only a few studies have addressed arthropods. Pyrophosphatases have been shown to regulate polyphosphate metabolism. However, these studies were restricted to trypanosomatids. Here we focus on the tick Rhipicephalus microplus, a haematophagous ectoparasite that is highly harmful to cattle. We produced a recombinant R. microplus pyrophosphatase (rRmPPase) with the aim of investigating its kinetic parameters using polyphosphates as substrate. Molecular docking assays of RmPPase with polyphosphates were also carried out. The kinetic and Hill coefficient parameters indicated that rRmPPase has a greater affinity, higher catalytic efficiency and increased cooperativity for sodium phosphate glass type 15 (polyP15 ) than for sodium tripolyphosphate (polyP3 ). Through molecular docking, we found that polyP3 binds close to the Mg2+ atoms in the catalytic region of the protein, participating in their coordination network, whereas polyP15 interactions involve negatively charged phosphate groups and basic amino acid residues, such as Lys56, Arg58 and Lys193; polyP15 has a more favourable theoretical binding affinity than polyP3 , thus supporting the kinetic data. This study shows, for the first time in arthropods, a pyrophosphatase with polyphosphatase activity, suggesting its participation in polyphosphate metabolism.
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Affiliation(s)
- C S Cruz
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
| | - E P Costa
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - J A Machado
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - J N Silva
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - N C Romeiro
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - J Moraes
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
| | - J R Silva
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
| | - R N Fonseca
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
| | - I S Vaz
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
- Centro de Biotecnologia e Faculdade de Veterinária, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - C Logullo
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
| | - E Campos
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
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19
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Varas MA, Riquelme-Barrios S, Valenzuela C, Marcoleta AE, Berríos-Pastén C, Santiviago CA, Chávez FP. Inorganic Polyphosphate Is Essential for Salmonella Typhimurium Virulence and Survival in Dictyostelium discoideum. Front Cell Infect Microbiol 2018; 8:8. [PMID: 29441327 PMCID: PMC5797601 DOI: 10.3389/fcimb.2018.00008] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/09/2018] [Indexed: 01/26/2023] Open
Abstract
Inorganic polyphosphate (polyP) deficiency in enteric bacterial pathogens reduces their ability to invade and establish systemic infections in different hosts. For instance, inactivation of the polyP kinase gene (ppk) encoding the enzyme responsible for polyP biosynthesis reduces invasiveness and intracellular survival of Salmonella enterica serovar Typhimurium (S. Typhimurium) in epithelial cells and macrophages in vitro. In addition, the virulence in vivo of a S. Typhimurium Δppk mutant is significantly reduced in a murine infection model. In spite of these observations, the role played by polyP during the Salmonella-host interaction is not well understood. The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In fact, many intracellular pathogens can survive within D. discoideum cells using molecular mechanisms also required to survive within macrophages. Recently, we established that S. Typhimurium is able to survive intracellularly in D. discoideum and identified relevant genes linked to virulence that are crucial for this process. The aim of this study was to determine the effect of a polyP deficiency in S. Typhimurium during its interaction with D. discoideum. To do this, we evaluated the intracellular survival of wild-type and Δppk strains of S. Typhimurium in D. discoideum and the ability of these strains to delay the social development of the amoeba. In contrast to the wild-type strain, the Δppk mutant was unable to survive intracellularly in D. discoideum and enabled the social development of the amoeba. Both phenotypes were complemented using a plasmid carrying a copy of the ppk gene. Next, we simultaneously evaluated the proteomic response of both S. Typhimurium and D. discoideum during host-pathogen interaction via global proteomic profiling. The analysis of our results allowed the identification of novel molecular signatures that give insight into Salmonella-Dictyostelium interaction. Altogether, our results indicate that inorganic polyP is essential for S. Typhimurium virulence and survival in D. discoideum. In addition, we have validated the use of global proteomic analyses to simultaneously evaluate the host-pathogen interaction of S. Typhimurium and D. discoideum. Furthermore, our infection assays using these organisms can be exploited to screen for novel anti-virulence molecules targeting inorganic polyP biosynthesis.
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Affiliation(s)
- Macarena A Varas
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Sebastián Riquelme-Barrios
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Camila Valenzuela
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Andrés E Marcoleta
- Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Camilo Berríos-Pastén
- Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Carlos A Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Francisco P Chávez
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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20
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Suess PM, Gomer RH. Extracellular Polyphosphate Inhibits Proliferation in an Autocrine Negative Feedback Loop in Dictyostelium discoideum. J Biol Chem 2016; 291:20260-9. [PMID: 27519410 DOI: 10.1074/jbc.m116.737825] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Indexed: 11/06/2022] Open
Abstract
Polyphosphate is a polymer of phosphate residues linked by high energy phosphoanhydride bonds. Despite being highly conserved throughout nature, its function is poorly understood. Here we show that Dictyostelium cells accumulate extracellular polyphosphate, and this acts to inhibit proliferation at high cell densities. In shaking culture, extracellular polyphosphate concentrations increase as cell density increases, and if the concentration of polyphosphate observed at the stationary phase is added to cells at mid-log, proliferation is halted. Adding an exopolyphosphatase to cell cultures or stationary phase conditioned medium decreases polyphosphate levels and abrogates the anti-proliferative effect. The cells show saturable binding of polyphosphate, suggesting the presence of a cell surface polyphosphate receptor. Extracellular polyphosphate accumulation is potentiated by decreased nutrient levels, potentially as a means to anticipate starvation. Loss of the Dictyostelium polyphosphate kinase DdPpk1 causes intracellular polyphosphate levels to become undetectable and negatively affects fitness, cytokinesis, and germination. However, cells lacking DdPpk1 accumulate ∼50% normal levels of extracellular polyphosphate, suggesting an additional means of synthesis. We found that cells lacking inositol hexakisphosphate kinase, which is responsible for the synthesis of the inositol pyrophosphates IP7 and IP8, reach abnormally high cell densities and show decreased extracellular polyphosphate levels. Two different enzymes thus appear to mediate the synthesis of Dictyostelium extracellular polyphosphate, which is used as a signal in an autocrine negative feedback loop to regulate cell proliferation.
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Affiliation(s)
- Patrick M Suess
- From the Department of Biology, Texas A&M University, College Station, Texas 77843-3474
| | - Richard H Gomer
- From the Department of Biology, Texas A&M University, College Station, Texas 77843-3474
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21
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Bravo-Toncio C, Álvarez JA, Campos F, Ortíz-Severín J, Varas M, Cabrera R, Lagos CF, Chávez FP. Dictyostelium discoideum as a surrogate host–microbe model for antivirulence screening in Pseudomonas aeruginosa PAO1. Int J Antimicrob Agents 2016; 47:403-9. [DOI: 10.1016/j.ijantimicag.2016.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 02/14/2016] [Accepted: 02/20/2016] [Indexed: 11/25/2022]
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22
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Developmental accumulation of inorganic polyphosphate affects germination and energetic metabolism in Dictyostelium discoideum. Proc Natl Acad Sci U S A 2016; 113:996-1001. [PMID: 26755590 DOI: 10.1073/pnas.1519440113] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Inorganic polyphosphate (polyP) is composed of linear chains of phosphate groups linked by high-energy phosphoanhydride bonds. However, this simple, ubiquitous molecule remains poorly understood. The use of nonstandardized analytical methods has contributed to this lack of clarity. By using improved polyacrylamide gel electrophoresis we were able to visualize polyP extracted from Dictyostelium discoideum. We established that polyP is undetectable in cells lacking the polyphosphate kinase (DdPpk1). Generation of this ppk1 null strain revealed that polyP is important for the general fitness of the amoebae with the mutant strain displaying a substantial growth defect. We discovered an unprecedented accumulation of polyP during the developmental program, with polyP increasing more than 100-fold. The failure of ppk1 spores to accumulate polyP results in a germination defect. These phenotypes are underpinned by the ability of polyP to regulate basic energetic metabolism, demonstrated by a 2.5-fold decrease in the level of ATP in vegetative ppk1. Finally, the lack of polyP during the development of ppk1 mutant cells is partially offset by an increase of both ATP and inositol pyrophosphates, evidence for a model in which there is a functional interplay between inositol pyrophosphates, ATP, and polyP.
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23
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Szymusiak M, Donovan AJ, Smith SA, Ransom R, Shen H, Kalkowski J, Morrissey JH, Liu Y. Colloidal Confinement of Polyphosphate on Gold Nanoparticles Robustly Activates the Contact Pathway of Blood Coagulation. Bioconjug Chem 2015; 27:102-9. [DOI: 10.1021/acs.bioconjchem.5b00524] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Stephanie A. Smith
- Department
of Biochemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | | | | | | | - James H. Morrissey
- Department
of Biochemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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24
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Sarabhai S, Harjai K, Sharma P, Capalash N. Ellagic acid derivatives from Terminalia chebula Retz. increase the susceptibility of Pseudomonas aeruginosa to stress by inhibiting polyphosphate kinase. J Appl Microbiol 2015; 118:817-25. [PMID: 25640983 DOI: 10.1111/jam.12733] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 12/16/2014] [Accepted: 12/16/2014] [Indexed: 11/27/2022]
Abstract
AIM Polyphosphate kinase 1 (PPK1) plays an important role in virulence, antibiotic resistance and survival under stress conditions and, therefore, is an attractive therapeutic target to control infections caused by multiple drug resistant Pseudomonas aeruginosa. This study explores the PPK1 inhibiting activity of ellagic acid derivatives (EADs) from Terminalia chebula Retz. that could increase the susceptibility of Ps. aeruginosa to in vitro stress conditions. METHODS AND RESULTS EADs reduced ppk1 gene expression by 93% (P < 0·05) and completely inhibited its activity (P < 0·01) at 0·5 mg ml(-1) . EADs-treated Ps. aeruginosa showed marked reduction in polyphosphate granules in cytosol. Expression of rpoS, the downstream master stress response regulator, was reduced by 94% (P < 0·05) and the sensitivity of Ps. aeruginosa increased many fold to desiccation, oxidative (H2 O2 ) and antibiotic (piperacillin) stresses. PPK-regulated swimming, swarming and twitching motilities and biofilm formation were also reduced significantly (P ≤ 0·05) in MPAO1 and the clinical strains of Ps. aeruginosa. CONCLUSION EADs from T. chebula inhibited PPK1 expression and its activity and increased the sensitivity of Ps. aeruginosa to desiccation and oxidative stress while reducing tolerance to piperacillin. SIGNIFICANCE AND IMPACT OF THE STUDY The study underlines the potential of EADs as therapeutic agent against Ps. aeruginosa.
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Affiliation(s)
- S Sarabhai
- Department of Microbiology, Panjab University, Chandigarh, India
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25
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Albi T, Serrano A. Two exopolyphosphatases with distinct molecular architectures and substrate specificities from the thermophilic green-sulfur bacterium Chlorobium tepidum TLS. Microbiology (Reading) 2014; 160:2067-2078. [DOI: 10.1099/mic.0.080952-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The genome of the thermophilic green-sulfur bacterium Chlorobium tepidum TLS possesses two genes encoding putative exopolyphosphatases (PPX; EC 3.6.1.11), namely CT0099 (ppx1, 993 bp) and CT1713 (ppx2, 1557 bp). The predicted polypeptides of 330 and 518 aa residues are Ppx-GppA phosphatases of different domain architectures – the largest one has an extra C-terminal HD domain – which may represent ancient paralogues. Both ppx genes were cloned and overexpressed in Escherichia coli BL21(DE3). While CtPPX1 was validated as a monomeric enzyme, CtPPX2 was found to be a homodimer. Both PPX homologues were functional, K+-stimulated phosphohydrolases, with an absolute requirement for divalent metal cations and a marked preference for Mg2+. Nevertheless, they exhibited remarkably different catalytic specificities with regard to substrate classes and chain lengths. Even though both enzymes were able to hydrolyse the medium-size polyphosphate (polyP) P13–18 (polyP mix with mean chain length of 13–18 phosphate residues), CtPPX1 clearly reached its highest catalytic efficiency with tripolyphosphate and showed substantial nucleoside triphosphatase (NTPase) activity, while CtPPX2 preferred long-chain polyPs (>300 Pi residues) and did not show any detectable NTPase activity. These catalytic features, taken together with the distinct domain architectures and molecular phylogenies, indicate that the two PPX homologues of Chl. tepidum belong to different Ppx-GppA phosphatase subfamilies that should play specific biochemical roles in nucleotide and polyP metabolisms. In addition, these results provide an example of the remarkable functional plasticity of the Ppx-GppA phosphatases, a family of proteins with relatively simple structures that are widely distributed in the microbial world.
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Affiliation(s)
- Tomás Albi
- Instituto de Bioquímica Vegetal y Fotosíntesis, Centro de Investigaciones Científicas Isla de la Cartuja, CSIC-Universidad de Sevilla, Spain
| | - Aurelio Serrano
- Instituto de Bioquímica Vegetal y Fotosíntesis, Centro de Investigaciones Científicas Isla de la Cartuja, CSIC-Universidad de Sevilla, Spain
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26
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Inositol hexakisphosphate kinase 1 maintains hemostasis in mice by regulating platelet polyphosphate levels. Blood 2013; 122:1478-86. [PMID: 23782934 DOI: 10.1182/blood-2013-01-481549] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Polyphosphate (polyP), a polymer of orthophosphate moieties released from the dense granules of activated platelets, is a procoagulant agent. Inositol pyrophosphates, another group of phosphate-rich molecules, consist of mono- and diphosphates substituted on an inositol ring. Diphosphoinositol pentakisphosphate (IP7), the most abundant inositol pyrophosphate, is synthesized on phosphorylation of inositol hexakisphosphate (IP6) by IP6 kinases, of which there are 3 mammalian isoforms (IP6K1/2/3) and a single yeast isoform. Yeast lacking IP6 kinase are devoid of polyP, suggesting a role for IP6 kinase in maintaining polyP levels. We theorized that the molecular link between IP6 kinase and polyP is conserved in mammals and investigated whether polyP-dependent platelet function is altered in IP6K1 knockout (Ip6k1(-/-)) mice. We observe a significant reduction in platelet polyP levels in Ip6k1(-/-) mice, along with slower platelet aggregation and lengthened plasma clotting time. Incorporation of polyP into fibrin clots was reduced in Ip6k1(-/-) mice, thereby altering clot ultrastructure, which was rescued on the addition of exogenous polyP. In vivo assays revealed longer tail bleeding time and resistance to thromboembolism in Ip6k1(-/-) mice. Taken together, our data suggest a novel role for IP6K1 in regulation of mammalian hemostasis via its control of platelet polyP levels.
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27
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Whitehead MP, Hooley P, W Brown MR. Horizontal transfer of bacterial polyphosphate kinases to eukaryotes: implications for the ice age and land colonisation. BMC Res Notes 2013; 6:221. [PMID: 23738841 PMCID: PMC3680246 DOI: 10.1186/1756-0500-6-221] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 05/11/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Studies of online database(s) showed that convincing examples of eukaryote PPKs derived from bacteria type PPK1 and PPK2 enzymes are rare and currently confined to a few simple eukaryotes. These enzymes probably represent several separate horizontal transfer events. Retention of such sequences may be an advantage for tolerance to stresses such as desiccation or nutrient depletion for simple eukaryotes that lack more sophisticated adaptations available to multicellular organisms. We propose that the acquisition of encoding sequences for these enzymes by horizontal transfer enhanced the ability of early plants to colonise the land. The improved ability to sequester and release inorganic phosphate for carbon fixation by photosynthetic algae in the ocean may have accelerated or even triggered global glaciation events. There is some evidence for DNA sequences encoding PPKs in a wider range of eukaryotes, notably some invertebrates, though it is unclear that these represent functional genes.Polyphosphate (poly P) is found in all cells, carrying out a wide range of essential roles. Studied mainly in prokaryotes, the enzymes responsible for synthesis of poly P in eukaryotes (polyphosphate kinases PPKs) are not well understood. The best characterised enzyme from bacteria known to catalyse the formation of high molecular weight polyphosphate from ATP is PPK1 which shows some structural similarity to phospholipase D. A second bacterial PPK (PPK2) resembles thymidylate kinase. Recent reports have suggested a widespread distribution of these bacteria type enzymes in eukaryotes. RESULTS On - line databases show evidence for the presence of genes encoding PPK1 in only a limited number of eukaryotes. These include the photosynthetic eukaryotes Ostreococcus tauri, O. lucimarinus, Porphyra yezoensis, Cyanidioschyzon merolae and the moss Physcomitrella patens, as well as the amoeboid symbiont Capsaspora owczarzaki and the non-photosynthetic eukaryotes Dictyostelium (3 species), Polysphondylium pallidum and Thecamonas trahens. A second bacterial PPK (PPK2) is found in just two eukaryotes (O. tauri and the sea anemone Nematostella vectensis). There is some evidence for PPK1 and PPK2 encoding sequences in other eukaryotes but some of these may be artefacts of bacterial contamination of gene libraries. CONCLUSIONS Evidence for the possible origins of these eukaryote PPK1s and PPK2s and potential prokaryote donors via horizontal gene transfer is presented. The selective advantage of acquiring and maintaining a prokaryote PPK in a eukaryote is proposed to enhance stress tolerance in a changing environment related to the capture and metabolism of inorganic phosphate compounds. Bacterial PPKs may also have enhanced the abilities of marine phytoplankton to sequester phosphate, hence accelerating global carbon fixation.
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Nikel PI, Chavarría M, Martínez-García E, Taylor AC, de Lorenzo V. Accumulation of inorganic polyphosphate enables stress endurance and catalytic vigour in Pseudomonas putida KT2440. Microb Cell Fact 2013; 12:50. [PMID: 23687963 PMCID: PMC3673903 DOI: 10.1186/1475-2859-12-50] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 05/15/2013] [Indexed: 11/25/2022] Open
Abstract
Background Accumulation of inorganic polyphosphate (polyP), a persistent trait throughout the whole Tree of Life, is claimed to play a fundamental role in enduring environmental insults in a large variety of microorganisms. The share of polyP in the tolerance of the soil bacterium Pseudomonas putida KT2440 to a suite of physicochemical stresses has been studied on the background of its capacity as a host of oxidative biotransformations. Results Cells lacking polyphosphate kinase (Ppk), which expectedly presented a low intracellular polyP level, were more sensitive to a number of harsh external conditions such as ultraviolet irradiation, addition of β-lactam antibiotics and heavy metals (Cd2+ and Cu2+). Other phenotypes related to a high-energy phosphate load (e.g., swimming) were substantially weakened as well. Furthermore, the ppk mutant was consistently less tolerant to solvents and its survival in stationary phase was significantly affected. In contrast, the major metabolic routes were not significantly influenced by the loss of Ppk as diagnosed from respiration patterns of the mutant in phenotypic microarrays. However, the catalytic vigour of the mutant decreased to about 50% of that in the wild-type strain as estimated from the specific growth rate of cells carrying the catabolic TOL plasmid pWW0 for m-xylene biodegradation. The catalytic phenotype of the mutant was restored by over-expressing ppk in trans. Some of these deficits could be explained by the effect of the ppk mutation on the expression profile of the rpoS gene, the stationary phase sigma factor, which was revealed by the analysis of a PrpoS → rpoS‘-’lacZ translational fusion. Still, every stress-related effect of lacking Ppk in P. putida was relatively moderate as compared to some of the conspicuous phenotypes reported for other bacteria. Conclusions While polyP can be involved in a myriad of cellular functions, the polymer seems to play a relatively secondary role in the genetic and biochemical networks that ultimately enable P. putida to endure environmental stresses. Instead, the main value of polyP could be ensuring a reservoire of energy during prolonged starvation. This is perhaps one of the reasons for polyP persistence in live systems despite its apparent lack of essentiality.
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Affiliation(s)
- Pablo I Nikel
- Systems and Synthetic Biology Program, Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain
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New insights into roles of acidocalcisomes and contractile vacuole complex in osmoregulation in protists. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 305:69-113. [PMID: 23890380 DOI: 10.1016/b978-0-12-407695-2.00002-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
While free-living protists are usually subjected to hyposmotic environments, parasitic protists are also in contact with hyperosmotic habitats. Recent work in one of these parasites, Trypanosoma cruzi, has revealed that its contractile vacuole complex, which usually collects and expels excess water as a mechanism of regulatory volume decrease after hyposmotic stress, has also a role in cell shrinking when the cells are submitted to hyperosmotic stress. Trypanosomes also have an acidic calcium store rich in polyphosphate (polyP), named the acidocalcisome, which is involved in their response to osmotic stress. Here, we review newly emerging insights on the role of acidocalcisomes and the contractile vacuole complex in the cellular response to hyposmotic and hyperosmotic stresses. We also review the current state of knowledge on the composition of these organelles and their other roles in calcium homeostasis and protein trafficking.
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Kulakovskaya T, Kulaev I. Enzymes of inorganic polyphosphate metabolism. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2013; 54:39-63. [PMID: 24420710 DOI: 10.1007/978-3-642-41004-8_3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inorganic polyphosphate (PolyP) is a linear polymer containing a few to several hundred orthophosphate residues linked by energy-rich phosphoanhydride bonds. Investigation of PolyP-metabolizing enzymes is important for medicine, because PolyPs perform numerous functions in the cells. In human organism, PolyPs are involved in the regulation of Ca(2+) uptake in mitochondria, bone tissue development, and blood coagulation. The essentiality of polyphosphate kinases in the virulence of pathogenic bacteria is a basis for the discovery of new antibiotics. The properties of the major enzymes of PolyP metabolism, first of all polyphosphate kinases and exopolyphosphatases, are described in the review. The main differences between the enzymes of PolyP biosynthesis and utilization of prokaryotic and eukaryotic cells, as well as the multiple functions of some enzymes of PolyP metabolism, are considered.
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Affiliation(s)
- Tatyana Kulakovskaya
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia,
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Morrissey JH, Choi SH, Smith SA. Polyphosphate: an ancient molecule that links platelets, coagulation, and inflammation. Blood 2012; 119:5972-9. [PMID: 22517894 PMCID: PMC3383012 DOI: 10.1182/blood-2012-03-306605] [Citation(s) in RCA: 266] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Inorganic polyphosphate is widespread in biology and exhibits striking prohemostatic, prothrombotic, and proinflammatory effects in vivo. Long-chain polyphosphate (of the size present in infectious microorganisms) is a potent, natural pathophysiologic activator of the contact pathway of blood clotting. Medium-chain polyphosphate (of the size secreted from activated human platelets) accelerates factor V activation, completely abrogates the anticoagulant function of tissue factor pathway inhibitor, enhances fibrin clot structure, and greatly accelerates factor XI activation by thrombin. Polyphosphate may have utility as a hemostatic agent, whereas antagonists of polyphosphate may function as novel antithrombotic/anti-inflammatory agents. The detailed molecular mechanisms by which polyphosphate modulates blood clotting reactions remain to be elucidated.
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Affiliation(s)
- James H Morrissey
- Biochemistry Department, University of Illinois, 506 S Mathews Ave, Urbana, IL 61801, USA.
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Simultaneous removal of phosphorus and nitrogen in a sequencing batch biofilm reactor with transgenic bacteria expressing polyphosphate kinase. Appl Microbiol Biotechnol 2012; 96:265-72. [PMID: 22218771 DOI: 10.1007/s00253-011-3839-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 12/07/2011] [Accepted: 12/09/2011] [Indexed: 10/14/2022]
Abstract
To improve phosphorus removal from wastewater, we constructed a high-phosphate-accumulating microorganism, KTPPK, using Pseudomonas putida KT2440 as a host. The expression plasmid was constructed by inserting and expressing polyphosphate kinase gene (ppk) from Microcystis aeruginosa NIES-843 into broad-host-range plasmid, pBBR1MCS-2. KTPPK was then added to a sequencing batch biofilm reactor (SBBFR) using lava as a biological carrier. The results showed that SBBFR with KTPPK not only efficiently removed COD, NH(3)-N, and NO(3)(-)-N but also had a high removal capacity for PO(4)(3-)-P, resulting in a low phosphorus concentration remaining in the outflow of the SBBFR. The biofilm increased by 30-53% on the lava in the SBBFR that contained KTPPK after 11 days when compared with the reactor that contained P. putida KT2440. Real-time quantitative polymerase chain reaction confirmed that the copy of ppk was maintained at about 3.5 × 10(10) copies per μL general DNA in the biofilm after 20 days. Thus, the transgenic bacteria KTPPK could maintain a high density and promote phosphorus removal in the SBBFR. In summary, this study indicates that the use of SBBFR with transgenic bacteria has the potential to remove phosphorus and nitrogen from wastewater.
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Shi T, Fu T, Xie J. Polyphosphate deficiency affects the sliding motility and biofilm formation of Mycobacterium smegmatis. Curr Microbiol 2011; 63:470-6. [PMID: 21882007 DOI: 10.1007/s00284-011-0004-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2011] [Accepted: 08/17/2011] [Indexed: 01/16/2023]
Abstract
Inorganic polyphosphate (polyP) is a ubiquitous linear polymer of hundreds of orthophosphate (Pi) residues linked by ATP-like, high-energy, phosphoanhydride bonds. The gene Rv1026 in Mycobacterium tuberculosis encodes a putative exopolyphosphatase which progressively hydrolyzes the terminal residues of polyP to liberate Pi. Rv1026 was cloned into the expressive plasmid pMV261. The resulting plasmid pRv1026 and the plasmid pMV261 were transformed into M. smegmatis strain mc(2)155 by electroporation. The recombinant M. smegmatis (pRv1026) showed relatively decreased polyP concentration and a phenotype different from the M. smegmatis (pMV261) in sliding motility and biofilm formation. The surfactant Tween 80 can enhance this effect on the sliding motility and biofilm formation of M. smegmatis. There are four different peaks between the gas chromatography of cellular wall fatty acid of the M. smegmatis (pRv1026) and the M. smegmatis (pMV261). These results indicate that polyP deficiency can affect the fatty acid composition of cellular wall and these alteration of cell wall might elucidate the reductive ability of strains to slide and form biofilm. This investigation provides novel recognition about the role of Rv1026, which provides novel clues for further study on the physiological role of Rv1026 in M. tuberculosis.
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Affiliation(s)
- Tingyu Shi
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, School of Life Sciences, Southwest University, Chongqing 400715, China
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Srikanta D, Yang M, Williams M, Doering TL. A sensitive high-throughput assay for evaluating host-pathogen interactions in Cryptococcus neoformans infection. PLoS One 2011; 6:e22773. [PMID: 21829509 PMCID: PMC3145667 DOI: 10.1371/journal.pone.0022773] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 06/29/2011] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Cryptococcus neoformans causes serious disease in immunocompromised individuals, leading to over 600,000 deaths per year worldwide. Part of this impact is due to the organism's ability to thwart what should be the mammalian hosts' first line of defense against cryptococcal infection: internalization by macrophages. Even when C. neoformans is engulfed by host phagocytes, it can survive and replicate within them rather than being destroyed; this ability is central in cryptococcal virulence. It is therefore critical to elucidate the interactions of this facultative intracellular pathogen with phagocytic cells of its mammalian host. METHODOLOGY/PRINCIPAL FINDINGS To accurately assess initial interactions between human phagocytic cells and fungi, we have developed a method using high-throughput microscopy to efficiently distinguish adherent and engulfed cryptococci and quantitate each population. This method offers significant advantages over currently available means of assaying host-fungal cell interactions, and remains statistically robust when implemented in an automated fashion appropriate for screening. It was used to demonstrate the sensitivity of human phagocytes to subtle changes in the cryptococcal capsule, a major virulence factor of this pathogen. CONCLUSIONS/SIGNIFICANCE Our high-throughput method for characterizing interactions between C. neoformans and mammalian phagocytic cells offers a powerful tool for elucidating the relationship between these cell types during pathogenesis. This approach will be useful for screens of this organism and has potentially broad applications for investigating host-pathogen interactions.
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Affiliation(s)
- Deepa Srikanta
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Meng Yang
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Matthew Williams
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Tamara L. Doering
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
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Abstract
Acidocalcisomes are acidic organelles containing calcium and a high concentration of phosphorus in the form of pyrophosphate (PP(i)) and polyphosphate (poly P). Organelles with these characteristics have been found from bacteria to human cells implying an early appearance and persistence over evolutionary time or their appearance by convergent evolution. Acidification of the organelles is driven by the presence of vacuolar proton pumps, one of which, the vacuolar proton pyrophosphatase, is absent in animals, where it is substituted by a vacuolar proton ATPase. A number of other pumps, antiporters, and channels have been described in acidocalcisomes of different species and are responsible for their internal content. Enzymes involved in the synthesis and degradation of PP(i) and poly P are present within the organelle. Acidocalcisomes function as storage sites for cations and phosphorus, and participate in PP(i) and poly P metabolism, calcium homeostasis, maintenance of intracellular pH, and osmoregulation. Experiments in which the acidocalcisome Ca(2+)-ATPase of different parasites were downregulated or eliminated, or acidocalcisome Ca(2+) was depleted revealed the importance of this store in Ca(2+) signaling needed for host invasion and virulence. Acidocalcisomes interact with other organelles in a number of organisms suggesting their association with the endosomal/lysosomal pathway, and are considered part of the lysosome-related group of organelles.
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Lima WC, Lelong E, Cosson P. What can Dictyostelium bring to the study of Pseudomonas infections? Semin Cell Dev Biol 2010; 22:77-81. [PMID: 21134479 DOI: 10.1016/j.semcdb.2010.11.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 11/24/2010] [Accepted: 11/29/2010] [Indexed: 11/29/2022]
Abstract
Bacterial infections are complex events. They are studied in a variety of simple model systems, using mammalian or non-mammalian hosts, all of which fail to reproduce fully the situation in infected patients. Each model presents a combination of conceptual, practical, and ethical advantages and disadvantages. In this review, we detail the use of Dictyostelium discoideum amoebae as a model to study Pseudomonas aeruginosa. More specifically, our aim is to explore what this additional model system can bring to our understanding of Pseudomonas infections. The study of interactions between Dictyostelium amoebae and Pseudomonas provides a view of the selection pressures exerted by environmental predators on Pseudomonas. It also represents a unique system to assess the virulence of very large numbers of Pseudomonas strains.
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Affiliation(s)
- Wanessa C Lima
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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Abstract
BACKGROUND INFORMATION Poly P (inorganic polyphosphate) is a polymer formed by P(i) residues linked by high-energy phosphoanhydride bonds. The presence of poly P in bacteria, fungi, algae and protists has been widely recognized, but the distribution of poly P in more complex eukaryotes has been poorly studied. Poly P accumulates, together with calcium, in acidic vesicles or acidocalcisomes in a number of organisms and possesses a diverse array of functions, including roles in stress response, blood clotting, inflammation, calcification, cell proliferation and apoptosis. RESULTS We report here that a considerable amount of phosphorus in the yolk of chicken eggs is in the form of poly P. DAPI (4',6-diamidino-2-phenylindole) staining showed that poly P is localized mainly in electron-dense vesicles located inside larger vacuoles (compound organelles) that are randomly distributed in the yolk. These internal vesicles were shown to contain calcium, potassium, sodium, magnesium, phosphorus, chlorine, iron and zinc, as detected by X-ray microanalysis and elemental mapping. These vesicles stain with the acidophilic dye Acridine Orange. The presence of poly P in organellar fractions of the egg yolk was evident in agarose gels stained with Toluidine Blue and DAPI. Of the total phosphate (Pi) of yolk organelles, 16% is present in the form of poly P. Total poly P content was not altered during the first 4 days of embryogenesis, but poly P chain length decreased after 1 day of development. CONCLUSIONS The results of the present study identify a novel organelle in chicken egg yolk comprising acidic vesicles with a morphology, physiology and composition similar to those of acidocalcisomes, within larger acidic vacuoles. The elemental composition of these acidocalcisomes is proportionally similar to the elemental composition of the yolk, suggesting that most of these elements are located in these organelles, which might be an important storage compartment in eggs.
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Abstract
Inorganic polyphosphate (Poly P) is a polymer of tens to hundreds of phosphate residues linked by "high-energy" phosphoanhydride bonds as in ATP. Found in abundance in all cells in nature, it is unique in its likely role in the origin and survival of species. Here, we present extensive evidence that the remarkable properties of Poly P as a polyanion have made it suited for a crucial role in the emergence of cells on earth. Beyond that, Poly P has proved in a variety of ways to be essential for growth of cells, their responses to stresses and stringencies, and the virulence of pathogens. In this review, we pay particular attention to the enzyme, polyphosphate kinase 1 (Poly P kinase 1 or PPK1), responsible for Poly P synthesis and highly conserved in many bacterial species, including 20 or more of the major pathogens. Mutants lacking PPK1 are defective in motility, quorum sensing, biofilm formation, and virulence. Structural studies are cited that reveal the conserved ATP-binding site of PPK1 at atomic resolution and reveal that the site can be blocked with minute concentrations of designed inhibitors. Another widely conserved enzyme is PPK2, which has distinctive kinetic properties and is also implicated in the virulence of some pathogens. Thus, these enzymes, absent in yeast and animals, are novel attractive targets for treatment of many microbial diseases. Still another enzyme featured in this review is one discovered in Dictyostelium discoideum that becomes an actin-like fiber concurrent with the synthesis, step by step, of a Poly P chain made from ATP. The Poly P-actin fiber complex, localized in the cell, lengthens and recedes in response to metabolic signals. Homologs of DdPPK2 are found in pathogenic protozoa and in the alga Chlamydomonas. Beyond the immediate relevance of Poly P as a target for anti-infective drugs, a large variety of cellular operations that rely on Poly P will be considered.
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Affiliation(s)
- Narayana N Rao
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Hothorn M, Neumann H, Lenherr ED, Wehner M, Rybin V, Hassa PO, Uttenweiler A, Reinhardt M, Schmidt A, Seiler J, Ladurner AG, Herrmann C, Scheffzek K, Mayer A. Catalytic Core of a Membrane-Associated Eukaryotic Polyphosphate Polymerase. Science 2009; 324:513-6. [DOI: 10.1126/science.1168120] [Citation(s) in RCA: 217] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Ikeno S, Yoshida T, Haruyama T. Artificial-enzyme gel membrane-based biosurveillance sensor with high reproducibility and long-term storage stability. Analyst 2009; 134:337-42. [DOI: 10.1039/b810846c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Tammenkoski M, Koivula K, Cusanelli E, Zollo M, Steegborn C, Baykov AA, Lahti R. Human Metastasis Regulator Protein H-Prune is a Short-Chain Exopolyphosphatase. Biochemistry 2008; 47:9707-13. [DOI: 10.1021/bi8010847] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marko Tammenkoski
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland, Department of Biochemistry and Biotechnological Medicine, Via Pansini 5, University Federico II of Naples, Italy, c/o CEINGE, Centro di Ingegneria Genetica e Biotecnologie Avanzate, Naples, Italy, Department of Physiological Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany, and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| | - Katja Koivula
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland, Department of Biochemistry and Biotechnological Medicine, Via Pansini 5, University Federico II of Naples, Italy, c/o CEINGE, Centro di Ingegneria Genetica e Biotecnologie Avanzate, Naples, Italy, Department of Physiological Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany, and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| | - Emilio Cusanelli
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland, Department of Biochemistry and Biotechnological Medicine, Via Pansini 5, University Federico II of Naples, Italy, c/o CEINGE, Centro di Ingegneria Genetica e Biotecnologie Avanzate, Naples, Italy, Department of Physiological Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany, and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| | - Massimo Zollo
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland, Department of Biochemistry and Biotechnological Medicine, Via Pansini 5, University Federico II of Naples, Italy, c/o CEINGE, Centro di Ingegneria Genetica e Biotecnologie Avanzate, Naples, Italy, Department of Physiological Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany, and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| | - Clemens Steegborn
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland, Department of Biochemistry and Biotechnological Medicine, Via Pansini 5, University Federico II of Naples, Italy, c/o CEINGE, Centro di Ingegneria Genetica e Biotecnologie Avanzate, Naples, Italy, Department of Physiological Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany, and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| | - Alexander A. Baykov
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland, Department of Biochemistry and Biotechnological Medicine, Via Pansini 5, University Federico II of Naples, Italy, c/o CEINGE, Centro di Ingegneria Genetica e Biotecnologie Avanzate, Naples, Italy, Department of Physiological Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany, and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| | - Reijo Lahti
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland, Department of Biochemistry and Biotechnological Medicine, Via Pansini 5, University Federico II of Naples, Italy, c/o CEINGE, Centro di Ingegneria Genetica e Biotecnologie Avanzate, Naples, Italy, Department of Physiological Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany, and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
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Carilla-Latorre S, Calvo-Garrido J, Bloomfield G, Skelton J, Kay RR, Ivens A, Martinez JL, Escalante R. Dictyostelium transcriptional responses to Pseudomonas aeruginosa: common and specific effects from PAO1 and PA14 strains. BMC Microbiol 2008; 8:109. [PMID: 18590548 PMCID: PMC2474670 DOI: 10.1186/1471-2180-8-109] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Accepted: 06/30/2008] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Pseudomonas aeruginosa is one of the most relevant human opportunistic bacterial pathogens. Two strains (PAO1 and PA14) have been mainly used as models for studying virulence of P. aeruginosa. The strain PA14 is more virulent than PAO1 in a wide range of hosts including insects, nematodes and plants. Whereas some of the differences might be attributable to concerted action of determinants encoded in pathogenicity islands present in the genome of PA14, a global analysis of the differential host responses to these P. aeruginosa strains has not been addressed. Little is known about the host response to infection with P. aeruginosa and whether or not the global host transcription is being affected as a defense mechanism or altered in the benefit of the pathogen. Since the social amoeba Dictyostelium discoideum is a suitable host to study virulence of P. aeruginosa and other pathogens, we used available genomic tools in this model system to study the transcriptional host response to P. aeruginosa infection. RESULTS We have compared the virulence of the P. aeruginosa PAO1 and PA14 using D. discoideum and studied the transcriptional response of the amoeba upon infection. Our results showed that PA14 is more virulent in Dictyostelium than PA01using different plating assays. For studying the differential response of the host to infection by these model strains, D. discoideum cells were exposed to either P. aeruginosa PAO1 or P. aeruginosa PA14 (mixed with an excess of the non-pathogenic bacterium Klebsiella aerogenes as food supply) and after 4 hours, cellular RNA extracted. A three-way comparison was made using whole-genome D. discoideum microarrays between RNA samples from cells treated with the two different strains and control cells exposed only to K. aerogenes. The transcriptomic analyses have shown the existence of common and specific responses to infection. The expression of 364 genes changed in a similar way upon infection with one or another strain, whereas 169 genes were differentially regulated depending on whether the infecting strain was either P. aeruginosa PAO1 or PA14. Effects on metabolism, signalling, stress response and cell cycle can be inferred from the genes affected. CONCLUSION Our results show that pathogenic Pseudomonas strains invoke both a common transcriptional response from Dictyostelium and a strain specific one, indicating that the infective process of bacterial pathogens can be strain-specific and is more complex than previously thought.
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Affiliation(s)
- Sergio Carilla-Latorre
- Instituto de Investigaciones Biomédicas Alberto Sols, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain.
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Brown MRW, Kornberg A. The long and short of it - polyphosphate, PPK and bacterial survival. Trends Biochem Sci 2008; 33:284-90. [PMID: 18487048 DOI: 10.1016/j.tibs.2008.04.005] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 04/17/2008] [Accepted: 04/17/2008] [Indexed: 12/12/2022]
Abstract
Inorganic polyphosphate (poly P) is present in all species tested to date, from each of the three kingdoms of life. Studied mainly in prokaryotes, poly P and its associated enzymes are important in diverse basic metabolism, in at least some structural functions and, notably, in stress responses. These numerous and unrelated roles for poly P are probably the consequence of its presence in life-forms from early in evolution. The genomes of many bacterial species, including pathogens, encode a homologue of a major poly P synthetic enzyme, poly P kinase 1 (PPK1). Loss of PPK1 results in reduced poly P levels, and deletion of the ppk1 gene in pathogens also results in a loss of virulence towards protozoa and animals. Thus far, no PPK1 homologue has been identified in higher-order eukaryotes and, therefore, PPK1 exhibits potential as a novel target for chemotherapy.
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Affiliation(s)
- Michael R W Brown
- Research Institute in Healthcare Science, Department of Pharmacy, University of Wolverhampton, Wulfruna Street, Wolverhampton, WV1 1SB, UK.
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Polyphosphate kinase 1, a conserved bacterial enzyme, in a eukaryote, Dictyostelium discoideum, with a role in cytokinesis. Proc Natl Acad Sci U S A 2007; 104:16486-91. [PMID: 17940044 DOI: 10.1073/pnas.0706847104] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Polyphosphate kinase 1 (PPK1), the principal enzyme responsible for reversible synthesis of polyphosphate (poly P) from the terminal phosphate of ATP, is highly conserved in bacteria and archaea. Dictyostelium discoideum, a social slime mold, is one of a few eukaryotes known to possess a PPK1 homolog (DdPPK1). Compared with PPK1 of Escherichia coli, DdPPK1 contains the conserved residues for ATP binding and autophosphorylation, but has an N-terminal extension of 370 aa, lacking homology with any known protein. Polyphosphate or ATP promote oligomerization of the enzyme in vitro. The DdPPK1 products are heterogeneous in chain length and shorter than those of E. coli. The unique DdPPK1 N-terminal domain was shown to be necessary for its enzymatic activity, cellular localization, and physiological functions. Mutants of DdPPK1, as previously reported, are defective in development, sporulation, and predation, and as shown here, in late stages of cytokinesis and cell division.
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Development of soil amoeba Dictyostelium discoideum as an expression system for recombinant human erythropoietin. World J Microbiol Biotechnol 2007. [DOI: 10.1007/s11274-007-9395-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Freimoser FM, Hürlimann HC, Jakob CA, Werner TP, Amrhein N. Systematic screening of polyphosphate (poly P) levels in yeast mutant cells reveals strong interdependence with primary metabolism. Genome Biol 2007; 7:R109. [PMID: 17107617 PMCID: PMC1794592 DOI: 10.1186/gb-2006-7-11-r109] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 10/04/2006] [Accepted: 11/15/2006] [Indexed: 11/30/2022] Open
Abstract
A systematic analysis of polyphosphate levels in yeast knockout strains for almost every non-essential gene identified 255 genes involved in the maintenance of normal polyphosphate content and provides insights into phosphate homeostasis. Background Inorganic polyphosphate (poly P) occurs universally in all organisms from bacteria to man. It functions, for example, as a phosphate and energy store, and is involved in the activation and regulation of proteins. Despite its ubiquitous occurrence and important functions, it is unclear how poly P is synthesized or how poly P metabolism is regulated in higher eukaryotes. This work describes a systematic analysis of poly P levels in yeast knockout strains mutated in almost every non-essential gene. Results After three consecutive screens, 255 genes (almost 4% of the yeast genome) were found to be involved in the maintenance of normal poly P content. Many of these genes encoded proteins functioning in the cytoplasm, the vacuole or in transport and transcription. Besides reduced poly P content, many strains also exhibited reduced total phosphate content, showed altered ATP and glycogen levels and were disturbed in the secretion of acid phosphatase. Conclusion Cellular energy and phosphate homeostasis is suggested to result from the equilibrium between poly P, ATP and free phosphate within the cell. Poly P serves as a buffer for both ATP and free phosphate levels and is, therefore, the least essential and consequently most variable component in this network. However, strains with reduced poly P levels are not only affected in their ATP and phosphate content, but also in other components that depend on ATP or free phosphate content, such as glycogen or secreted phosphatase activity.
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Affiliation(s)
| | | | - Claude A Jakob
- Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Thomas P Werner
- Institute of Plant Sciences, ETH Zurich, 8092 Zurich, Switzerland
| | - Nikolaus Amrhein
- Institute of Plant Sciences, ETH Zurich, 8092 Zurich, Switzerland
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Fraley CD, Rashid MH, Lee SSK, Gottschalk R, Harrison J, Wood PJ, Brown MRW, Kornberg A. A polyphosphate kinase 1 (ppk1) mutant of Pseudomonas aeruginosa exhibits multiple ultrastructural and functional defects. Proc Natl Acad Sci U S A 2007; 104:3526-31. [PMID: 17360677 PMCID: PMC1803759 DOI: 10.1073/pnas.0609733104] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa, of medical, environmental, and industrial importance, depends on inorganic polyphosphate (poly P) for a wide range of functions, especially survival. Mutants of PAO1 lacking poly P kinase 1, PPK1, the enzyme responsible for most poly P synthesis in Escherichia coli and other bacteria, are defective in motility, quorum sensing, biofilm formation, and virulence. We describe here multiple defects in the ppk1 mutant PAOM5, including a striking compaction of the nucleoid, distortion of the cell envelope, lack of planktonic motility and exopolymer production, and susceptibility to the beta-lactam antibiotic carbenicillin as well as desiccation. We propose that P. aeruginosa with reduced poly P levels undergoes ultrastructural changes that contribute to profound deficiencies in cellular functions.
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Affiliation(s)
- Cresson D. Fraley
- *Department of Biochemistry, Stanford University School of Medicine, 279 West Campus Drive, Stanford, CA 94305-5307
| | - M. Harunur Rashid
- Genencor International, Inc., 925 Page Mill Road, Palo Alto, CA 94304
| | - Sam S. K. Lee
- ICOS Corporation, 22021 20th Avenue SE, Bothell, WA 98021
| | | | | | - Pauline J. Wood
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom; and
| | - Michael R. W. Brown
- Research Institute of Healthcare Science, School of Applied Sciences, University of Wolverhampton, Wulfruna Street, Wolverhampton WV1 1SB, United Kingdom
| | - Arthur Kornberg
- *Department of Biochemistry, Stanford University School of Medicine, 279 West Campus Drive, Stanford, CA 94305-5307
- To whom correspondence should be addressed. E-mail:
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Ki S, Sugihara F, Kasahara K, Tochio H, Shirakawa M, Kokubo T. Magnetic resonance-based visualization of gene expression in mammalian cells using a bacterial polyphosphate kinase reporter gene. Biotechniques 2007; 42:209-15. [PMID: 17373486 DOI: 10.2144/000112319] [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] [Indexed: 11/23/2022] Open
Abstract
Gene expression reporter systems, in which a promoter of interest is cloned upstream of a readily assayed reporter gene, have been developed and used extensively to study gene expression in prokaryotes and eukaryotes. Unfortunately, most of these systems cannot be used to assay gene expression in nonsuperficial tissues in living organisms. This study examines a novel reporter gene system based on the gene encoding Escherichia coli polyphosphate kinase (PPK), which can be used to monitor gene expression in mammalian cells. PPK catalyzes the synthesis of inorganic polyphosphate (polyP) from ATP, and because mammalian cells do not contain detectable levels of polyP, PPK activity can be measured in mammalian cells using 31P-magnetic resonance spectroscopy or 31P-magnetic resonance imaging. The ppk reporter gene system described here is noninvasive, does not require an exogenous substrate, and can potentially be used in internal tissues of living organisms.
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Affiliation(s)
- Sewon Ki
- Yokohama City University, Yokohama, Japan
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Tammenkoski M, Moiseev V, Lahti M, Ugochukwu E, Brondijk THC, White SA, Lahti R, Baykov AA. Kinetic and mutational analyses of the major cytosolic exopolyphosphatase from Saccharomyces cerevisiae. J Biol Chem 2007; 282:9302-9311. [PMID: 17215253 DOI: 10.1074/jbc.m609423200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast exopolyphosphatase (scPPX) processively splits off the terminal phosphate group from linear polyphosphates longer than pyrophosphate. scPPX belongs to the DHH phosphoesterase superfamily and is evolutionarily close to the well characterized family II pyrophosphatase (PPase). Here, we used steady-state kinetic and binding measurements to elucidate the metal cofactor requirement for scPPX catalysis over the pH range 4.2-9.5. A single tight binding site for Mg(2+) (K(d) of 24 microm) was detected by equilibrium dialysis. Steady-state kinetic analysis of tripolyphosphate hydrolysis revealed a second site that binds Mg(2+) in the millimolar range and modulates substrate binding. This step requires two protonated and two deprotonated enzyme groups with pK(a) values of 5.0-5.3 and 7.6-8.2, respectively. The catalytic step requiring two deprotonated groups (pK(a) of 4.6 and 5.6) is modulated by ionization of a third group (pK(a) of 8.7). Conservative mutations of Asp(127), His(148), His(149) (conserved in scPPX and PPase), and Asn(35) (His in PPase) reduced activity by a factor of 600-5000. N35H and D127E substitutions reduced the Mg(2+) affinity of the tight binding site by 25-60-fold. Contrary to expectations, the N35H variant was unable to hydrolyze pyrophosphate, but markedly altered metal cofactor specificity, displaying higher catalytic activity with Co(2+) bound to the weak binding site versus the Mg(2+)- or Mn(2+)-bound enzyme. These results provide an initial step toward understanding the dynamics of scPPX catalysis and reveal significant functional differences between structurally similar scPPX and family II PPase.
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Affiliation(s)
- Marko Tammenkoski
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland
| | - ViktorM Moiseev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| | - Matti Lahti
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland
| | - Emilie Ugochukwu
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - T Harma C Brondijk
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Scott A White
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Reijo Lahti
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland.
| | - Alexander A Baykov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia.
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Rangarajan ES, Nadeau G, Li Y, Wagner J, Hung MN, Schrag JD, Cygler M, Matte A. The structure of the exopolyphosphatase (PPX) from Escherichia coli O157:H7 suggests a binding mode for long polyphosphate chains. J Mol Biol 2006; 359:1249-60. [PMID: 16678853 DOI: 10.1016/j.jmb.2006.04.031] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 04/13/2006] [Accepted: 04/13/2006] [Indexed: 12/12/2022]
Abstract
Polyphosphate (polyP) is a linear polymer consisting of tens to hundreds of phosphate molecules joined together by high-energy anhydride bonds. These polymers are found in virtually all prokaryotic and eukaryotic cells and perform many functions; prominent among them are the responses to many stresses. Polyphosphate is synthesized by polyP kinase (PPK), using the terminal phosphate of ATP as the substrate, and degraded to inorganic phosphate by both endo- and exopolyphosphatases. Here we report the crystal structure and analysis of the polyphosphate phosphatase PPX from Escherichia coli O157:H7 refined at 2.2 Angstroms resolution. PPX is made of four domains. Domains I and II display structural similarity with one another and share the ribonuclease-H-like fold. Domain III bears structural similarity to the N-terminal, HD domain of SpoT. Domain IV, the smallest domain, has structural counterparts in cold-shock associated RNA-binding proteins but is of unknown function in PPX. The putative PPX active site is located at the interface between domains I and II. In the crystal structure of PPX these two domains are close together and represent the "closed" state. Comparison with the crystal structure of PPX/GPPA from Aquifex aeolicus reveals close structural similarity between domains I and II of the two enzymes, with the PPX/GPPA representing an "open" state. A striking feature of the dimer is a deep S-shaped canyon extending along the dimer interface and lined with positively charged residues. The active site region opens to this canyon. We postulate that this is a likely site of polyP binding.
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