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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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2
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Neville N, Lehotsky K, Jia Z. Back on the chain gang: polyphosphate modification of proteins. Trends Biochem Sci 2024:S0968-0004(24)00153-1. [PMID: 38945730 DOI: 10.1016/j.tibs.2024.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Revised: 06/10/2024] [Accepted: 06/11/2024] [Indexed: 07/02/2024]
Abstract
Polyphosphate (polyP) mediates a plethora of biological functions. Understanding the polyP-protein interactome will help clarify the mechanisms underpinning these functions. Recent studies demonstrating a strong but noncovalent modification of lysine and histidine repeat proteins by polyP have provided new insights into polyP-protein biochemistry with implications for research and therapeutics.
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Affiliation(s)
- Nolan Neville
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Kirsten Lehotsky
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
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3
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Neville N, Lehotsky K, Klupt KA, Downey M, Jia Z. Polyphosphate attachment to lysine repeats is a non-covalent protein modification. Mol Cell 2024; 84:1802-1810.e4. [PMID: 38701741 DOI: 10.1016/j.molcel.2024.03.028] [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: 10/19/2023] [Revised: 03/12/2024] [Accepted: 03/29/2024] [Indexed: 05/05/2024]
Abstract
Polyphosphate (polyP) is a chain of inorganic phosphate that is present in all domains of life and affects diverse cellular phenomena, ranging from blood clotting to cancer. A study by Azevedo et al. described a protein modification whereby polyP is attached to lysine residues within polyacidic serine and lysine (PASK) motifs via what the authors claimed to be covalent phosphoramidate bonding. This was based largely on the remarkable ability of the modification to survive extreme denaturing conditions. Our study demonstrates that lysine polyphosphorylation is non-covalent, based on its sensitivity to ionic strength and lysine protonation and absence of phosphoramidate bond formation, as analyzed via 31P NMR. Ionic interaction with lysine residues alone is sufficient for polyP modification, and we present a new list of non-PASK lysine repeat proteins that undergo polyP modification. This work clarifies the biochemistry of polyP-lysine modification, with important implications for both studying and modulating this phenomenon. This Matters Arising paper is in response to Azevedo et al. (2015), published in Molecular Cell. See also the Matters Arising Response by Azevedo et al. (2024), published in this issue.
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Affiliation(s)
- Nolan Neville
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Kirsten Lehotsky
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Kody A Klupt
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Michael Downey
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; Ottawa Institute of Systems Biology, Ottawa, ON K1H 8M5, Canada
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada.
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4
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Baijal K, Abramchuk I, Herrera CM, Mah TF, Trent MS, Lavallée-Adam M, Downey M. Polyphosphate kinase regulates LPS structure and polymyxin resistance during starvation in E. coli. PLoS Biol 2024; 22:e3002558. [PMID: 38478588 PMCID: PMC10962826 DOI: 10.1371/journal.pbio.3002558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 03/25/2024] [Accepted: 02/21/2024] [Indexed: 03/26/2024] Open
Abstract
Polyphosphates (polyP) are chains of inorganic phosphates that can reach over 1,000 residues in length. In Escherichia coli, polyP is produced by the polyP kinase (PPK) and is thought to play a protective role during the response to cellular stress. However, the molecular pathways impacted by PPK activity and polyP accumulation remain poorly characterized. In this work, we used label-free mass spectrometry to study the response of bacteria that cannot produce polyP (Δppk) during starvation to identify novel pathways regulated by PPK. In response to starvation, we found 92 proteins significantly differentially expressed between wild-type and Δppk mutant cells. Wild-type cells were enriched for proteins related to amino acid biosynthesis and transport, while Δppk mutants were enriched for proteins related to translation and ribosome biogenesis, suggesting that without PPK, cells remain inappropriately primed for growth even in the absence of the required building blocks. From our data set, we were particularly interested in Arn and EptA proteins, which were down-regulated in Δppk mutants compared to wild-type controls, because they play a role in lipid A modifications linked to polymyxin resistance. Using western blotting, we confirm differential expression of these and related proteins in K-12 strains and a uropathogenic isolate, and provide evidence that this mis-regulation in Δppk cells stems from a failure to induce the BasRS two-component system during starvation. We also show that Δppk mutants unable to up-regulate Arn and EptA expression lack the respective L-Ara4N and pEtN modifications on lipid A. In line with this observation, loss of ppk restores polymyxin sensitivity in resistant strains carrying a constitutively active basR allele. Overall, we show a new role for PPK in lipid A modification during starvation and provide a rationale for targeting PPK to sensitize bacteria towards polymyxin treatment. We further anticipate that our proteomics work will provide an important resource for researchers interested in the diverse pathways impacted by PPK.
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Affiliation(s)
- Kanchi Baijal
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Cellular & Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Iryna Abramchuk
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Carmen M. Herrera
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Thien-Fah Mah
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- Centre for Infection, Immunity, and Inflammation, University of Ottawa, Ottawa, Ontario, Canada
| | - M. Stephen Trent
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Mathieu Lavallée-Adam
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Michael Downey
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Cellular & Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
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5
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Baijal K, Abramchuk I, Herrera CM, Stephen Trent M, Lavallée-Adam M, Downey M. Proteomics analysis reveals a role for E. coli polyphosphate kinase in membrane structure and polymyxin resistance during starvation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.06.546892. [PMID: 37461725 PMCID: PMC10350021 DOI: 10.1101/2023.07.06.546892] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Polyphosphates (polyP) are chains of inorganic phosphates that can reach over 1000 residues in length. In Escherichia coli, polyP is produced by the polyP kinase (PPK) and is thought to play a protective role during the response to cellular stress. However, the molecular pathways impacted by PPK activity and polyP accumulation remain poorly characterized. In this work we used label-free mass spectrometry to study the response of bacteria that cannot produce polyP (∆ppk) during starvation to identify novel pathways regulated by PPK. In response to starvation, we found 92 proteins significantly differentially expressed between wild-type and ∆ppk mutant cells. Wild-type cells were enriched for proteins related to amino acid biosynthesis and transport, while Δppk mutants were enriched for proteins related to translation and ribosome biogenesis, suggesting that without PPK, cells remain inappropriately primed for growth even in the absence of required building blocks. From our dataset, we were particularly interested in Arn and EptA proteins, which were downregulated in ∆ppk mutants compared to wild-type controls, because they play a role in lipid A modifications linked to polymyxin resistance. Using western blotting, we confirm differential expression of these and related proteins, and provide evidence that this mis-regulation in ∆ppk cells stems from a failure to induce the BasS/BasR two-component system during starvation. We also show that ∆ppk mutants unable to upregulate Arn and EptA expression lack the respective L-Ara4N and pEtN modifications on lipid A. In line with this observation, loss of ppk restores polymyxin sensitivity in resistant strains carrying a constitutively active basR allele. Overall, we show a new role for PPK in lipid A modification during starvation and provide a rationale for targeting PPK to sensitize bacteria towards polymyxin treatment. We further anticipate that our proteomics work will provide an important resource for researchers interested in the diverse pathways impacted by PPK.
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Affiliation(s)
- Kanchi Baijal
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Cellular & Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Iryna Abramchuk
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Carmen M. Herrera
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - M. Stephen Trent
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Mathieu Lavallée-Adam
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Michael Downey
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Cellular & Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
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6
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Deng S. The origin of genetic and metabolic systems: Evolutionary structuralinsights. Heliyon 2023; 9:e14466. [PMID: 36967965 PMCID: PMC10036676 DOI: 10.1016/j.heliyon.2023.e14466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 02/27/2023] [Accepted: 03/06/2023] [Indexed: 03/16/2023] Open
Abstract
DNA is derived from reverse transcription and its origin is related to reverse transcriptase, DNA polymerase and integrase. The gene structure originated from the evolution of the first RNA polymerase. Thus, an explanation of the origin of the genetic system must also explain the evolution of these enzymes. This paper proposes a polymer structure model, termed the stable complex evolution model, which explains the evolution of enzymes and functional molecules. Enzymes evolved their functions by forming locally tightly packed complexes with specific substrates. A metabolic reaction can therefore be considered to be the result of adaptive evolution in this way when a certain essential molecule is lacking in a cell. The evolution of the primitive genetic and metabolic systems was thus coordinated and synchronized. According to the stable complex model, almost all functional molecules establish binding affinity and specific recognition through complementary interactions, and functional molecules therefore have the nature of being auto-reactive. This is thermodynamically favorable and leads to functional duplication and self-organization. Therefore, it can be speculated that biological systems have a certain tendency to maintain functional stability or are influenced by an inherent selective power. The evolution of dormant bacteria may support this hypothesis, and inherent selectivity can be unified with natural selection at the molecular level.
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He C, Li B, Gong Z, Huang S, Liu X, Wang J, Xie J, Shi T. Polyphosphate kinase 1 is involved in formation, the morphology and ultramicrostructure of biofilm of Mycobacterium smegmatis and its survivability in macrophage. Heliyon 2023; 9:e14513. [PMID: 36967885 PMCID: PMC10034464 DOI: 10.1016/j.heliyon.2023.e14513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 03/06/2023] [Accepted: 03/09/2023] [Indexed: 03/17/2023] Open
Abstract
The most unique characteristic of Mycobacterium tuberculosis is persistence in the human host, and the biofilm formation is related to the persistance. Polyphosphate (polyP) kinase 1 (PPK1) is conserved in Mycobacteria and is responsible for polyP synthesis. polyP is a chain molecule linked by high-energy phosphate bonds, which is considered to play a very important role in bacterial persistence. However, the relationship of PPK1 and mycobacterial biofilm formation is still adequately unclear. In current study, ppk1-deficient mutant (MT), ppk1-complemented (CT) and wild-type strains of M. smegmatis mc2 155 were used to investigate the formation, morphology and ultramicrostructure of the biofilm and to analyze the lipid levels and susceptibility to vancomycin antibiotic. And then WT, MT and CT strains were used to infect macrophages and to analyze the expression levels of various inflammatory factors, respectively. We found that PPK1 was required for M. smegmatis polyP production in vivo and polyP deficiency not only attenuated the biofilm formation, but also altered the phenotype and ultramicrostructure of the biofilm and reduced the cell lipid composition (except for C16.1 and C17.1, most of the fatty acid components from C8-C24). Moreover, the ppk1-deficient mutant was also significantly more sensitive to vancomycin which targets the cell wall, and its ability to survive in macrophages was decreased, which was related to the change of the expression level of inflammatory factors in macrophage. This study demonstrates that the PPK1 can affect the biofilm structure through affecting the content of short chain fatty acid and promote intracellular survival of M. smegmatis by altering the expression of inflammatory factors. These findings establish a basis for investigating the role of PPK1 in the persistence of M. tuberculosis, and provide clues for treating latent infection of M. tuberculosis with PPK1 as a potential drug target.
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Affiliation(s)
- Cailin He
- Medical School of Hubei Minzu University, Enshi, 445000, China
| | - Bo Li
- Medical School of Hubei Minzu University, Enshi, 445000, China
| | - Zhen Gong
- Institute of Modern Biopharmaceuticals, School of Life Sciences, Southwest University, Chongqing, 400715, China
| | - Sheng Huang
- Medical School of Hubei Minzu University, Enshi, 445000, China
- Institute of Selenium Science and Industry of Hubei Minzu University, Enshi, 445000, China
| | - Xu Liu
- Medical School of Hubei Minzu University, Enshi, 445000, China
- Institute of Selenium Science and Industry of Hubei Minzu University, Enshi, 445000, China
| | - Jiajun Wang
- Medical School of Hubei Minzu University, Enshi, 445000, China
| | - Jianping Xie
- Institute of Modern Biopharmaceuticals, School of Life Sciences, Southwest University, Chongqing, 400715, China
- Corresponding author. Institute of Modern Biopharmaceuticals, School of Life Sciences, Southwest University, Chongqing, 400715, China.
| | - Tingyu Shi
- Medical School of Hubei Minzu University, Enshi, 445000, China
- Hubei Key Laboratory of Biological Resources Protection and Utilization, Enshi, 445000, China
- Institute of Selenium Science and Industry of Hubei Minzu University, Enshi, 445000, China
- Corresponding author. Medical School of Hubei Minzu University, Enshi, 445000, China.
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8
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Exopolyphosphatases PPX1 and PPX2 from Mycobacterium tuberculosis regulate dormancy response and pathogenesis. Microb Pathog 2022; 173:105885. [DOI: 10.1016/j.micpath.2022.105885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/12/2022] [Accepted: 11/12/2022] [Indexed: 11/21/2022]
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9
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Bacterial Membrane Vesicles as a Novel Strategy for Extrusion of Antimicrobial Bismuth Drug in Helicobacter pylori. mBio 2022; 13:e0163322. [PMID: 36154274 PMCID: PMC9601102 DOI: 10.1128/mbio.01633-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Bacterial antibiotic resistance is a major threat to human health. A combination of antibiotics with metals is among the proposed alternative treatments. Only one such combination is successfully used in clinics; it associates antibiotics with the metal bismuth to treat infections by Helicobacter pylori. This bacterial pathogen colonizes the human stomach and is associated with gastric cancer, killing 800,000 individuals yearly. The effect of bismuth in H. pylori treatment is not well understood in particular for sublethal doses such as those measured in the plasma of treated patients. We addressed this question and observed that bismuth induces the formation of homogeneously sized membrane vesicles (MVs) with unique protein cargo content enriched in bismuth-binding proteins, as shown by quantitative proteomics. Purified MVs of bismuth-exposed bacteria were strongly enriched in bismuth as measured by inductively coupled plasma optical emission spectrometry (ICP-OES), unlike bacterial cells from which they originate. Thus, our results revealed a novel function of MVs in bismuth detoxification, where secreted MVs act as tool to discard bismuth from the bacteria. Bismuth also induces the formation of intracellular polyphosphate granules that are associated with changes in nucleoid structure. Nucleoid compaction in response to bismuth was established by immunogold electron microscopy and refined by the first chromosome conformation capture (Hi-C) analysis of H. pylori. Our results reveal that even low doses of bismuth induce profound changes in H. pylori physiology and highlight a novel defense mechanism that involves MV-mediated bismuth extrusion from the bacteria and a probable local DNA protective response where polyphosphate granules are associated with nucleoid compaction.
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Krzyżek P, Grande R. Transformation of Helicobacter pylori into Coccoid Forms as a Challenge for Research Determining Activity of Antimicrobial Substances. Pathogens 2020; 9:pathogens9030184. [PMID: 32143312 PMCID: PMC7157236 DOI: 10.3390/pathogens9030184] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/01/2020] [Accepted: 03/03/2020] [Indexed: 12/12/2022] Open
Abstract
Morphological variability is one of the phenotypic features related to adaptation of microorganisms to stressful environmental conditions and increased tolerance to antimicrobial substances. Helicobacter pylori, a gastric mucosal pathogen, is characterized by a high heterogeneity and an ability to transform from a spiral to a coccoid form. The presence of the coccoid form is associated with the capacity to avoid immune system detection and to promote therapeutic failures. For this reason, it seems that the investigation for new, alternative methods combating H. pylori should include research of coccoid forms of this pathogen. The current review aimed at collecting information about the activity of antibacterial substances against H. pylori in the context of the morphological variability of this bacterium. The collected data was discussed in terms of the type of substances used, applied research techniques, and interpretation of results. The review was extended by a polemic on the limitations in determining the viability of coccoid H. pylori forms. Finally, recommendations which can help in future research aiming to find new compounds with a potential to eradicate H. pylori have been formulated.
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Affiliation(s)
- Paweł Krzyżek
- Department of Microbiology, Faculty of Medicine, Wroclaw Medical University, 50-368 Wroclaw, Poland
- Correspondence:
| | - Rossella Grande
- Center for Aging Science and Translational Medicine (CeSI-MeT), Via Luigi Polacchi, 11, 66100 Chieti, Italy;
- Department of Pharmacy, University “G. d’Annunzio” of Chieti-Pescara, Via dei Vestini, 31, 66100 Chieti, Italy
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11
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Tiwari P, Gosain TP, Singh M, Sankhe GD, Arora G, Kidwai S, Agarwal S, Chugh S, Saini DK, Singh R. Inorganic polyphosphate accumulation suppresses the dormancy response and virulence in Mycobacterium tuberculosis. J Biol Chem 2019; 294:10819-10832. [PMID: 31113860 DOI: 10.1074/jbc.ra119.008370] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/07/2019] [Indexed: 11/06/2022] Open
Abstract
Stringent response pathways involving inorganic polyphosphate (PolyP) play an essential role in bacterial stress adaptation and virulence. The intracellular levels of PolyP are modulated by the activities of polyphosphate kinase-1 (PPK1), polyphosphate kinase-2 (PPK2), and exopolyphosphatases (PPXs). The genome of Mycobacterium tuberculosis encodes two functional PPXs, and simultaneous deletion of ppx1 and ppx2 results in a defect in biofilm formation. We demonstrate here that these PPXs cumulatively contribute to the ability of M. tuberculosis to survive in nutrient-limiting, low-oxygen growth conditions and also in macrophages. Characterization of single (Δppx2) and double knockout (dkppx) strains of M. tuberculosis indicated that PPX-mediated PolyP degradation is essential for establishing bacterial infection in guinea pigs. RNA-Seq-based transcriptional profiling revealed that relative to the parental strain, the expression levels of DosR regulon-regulated dormancy genes were significantly reduced in the dkppx mutant strain. In concordance, we also provide evidence that PolyP inhibits the autophosphorylation activities associated with DosT and DosS sensor kinases. The results in this study uncover that enzymes involved in PolyP homeostasis play a critical role in M. tuberculosis physiology and virulence and are attractive targets for developing more effective therapeutic interventions.
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Affiliation(s)
- Prabhakar Tiwari
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, Haryana 121001, India and
| | - Tannu Priya Gosain
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, Haryana 121001, India and
| | - Mamta Singh
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, Haryana 121001, India and
| | | | - Garima Arora
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, Haryana 121001, India and
| | - Saqib Kidwai
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, Haryana 121001, India and
| | - Sakshi Agarwal
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, Haryana 121001, India and
| | - Saurabh Chugh
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, Haryana 121001, India and
| | - Deepak K Saini
- Centre for BioSystems Science and Engineering and; Department of Molecular Reproduction, Development, and Genetics, Biological Sciences Building, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Ramandeep Singh
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, Haryana 121001, India and.
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12
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Wang Z, Cumming BM, Mao C, Zhu Y, Lu P, Steyn AJC, Chen S, Hu Y. RbpA and σ B association regulates polyphosphate levels to modulate mycobacterial isoniazid-tolerance. Mol Microbiol 2018; 108:627-640. [PMID: 29575247 DOI: 10.1111/mmi.13952] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2018] [Indexed: 12/13/2022]
Abstract
To facilitate survival under drug stresses, a small population of Mycobacterium tuberculosis can tolerate bactericidal concentrations of drugs without genetic mutations. These drug-tolerant mycobacteria can be induced by environmental stresses and contribute to recalcitrant infections. However, mechanisms underlying the development of drug-tolerant mycobacteria remain obscure. Herein, we characterized a regulatory pathway which is important for the tolerance to isoniazid (INH) in Mycobacterium smegmatis. We found that the RNA polymerase binding protein RbpA associates with the stress response sigma factor σB , to activate the transcription of ppk1, the gene encoding polyphosphate kinase. Subsequently, intracellular levels of inorganic polyphosphate increase to promote INH-tolerant mycobacteria. Interestingly, σB and ppk1 expression varied proportionately in mycobacterial populations and positively correlated with tolerance to INH in individual mycobacteria. Moreover, sigB and ppk1 transcription are both induced upon nutrient depletion, a condition that stimulates the formation of INH-tolerant mycobacteria. Over-expression of ppk1 in rbpA knockdown or sigB deleted strains successfully restored the number of INH-tolerant mycobacteria under both normal growth and nutrient starved conditions. These data suggest that RbpA and σB regulate ppk1 expression to control drug tolerance both during the logarithmic growth phase and under the nutrition starved conditions.
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Affiliation(s)
- Zhongwei Wang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | | | - Chunyou Mao
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yan Zhu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Pei Lu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Adrie J C Steyn
- Africa Health Research Institute, Durban, South Africa.,Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yangbo Hu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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13
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Poursina F, Fagri J, Mirzaei N, Safaei HG. Overexpression of spoT gene in coccoid forms of clinical Helicobacter pylori isolates. Folia Microbiol (Praha) 2018; 63:459-465. [PMID: 29327293 DOI: 10.1007/s12223-017-0557-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 10/05/2017] [Indexed: 12/31/2022]
Abstract
Helicobacter pylori (H. pylori) can convert to coccoid form in unfavorable conditions or as a result of antibiotic treatment. In order to adapt to harsh environments, H. pylori requires a stringent response which, encoded by the spoT gene, has a bifunctional enzyme possessing both (p)ppGpp synthetic and degrading activity. Our goal in this study was to compare spoT gene expression in spiral and induced coccoid forms of H. pylori with use of amoxicillin. First, clinical isolate coccoid forms were induced with amoxicillin; then, the viability test was analyzed by flow cytometer. After RNA extraction, cDNA synthesis and designing a specific primer for spoT gene, evaluation of the desired gene expression in both forms were studied. Bacterial isolates exposed to amoxicillin at MIC and 1/2 MIC induced morphological conversion better and faster than other MIC concentration. The expression of spoT gene was significantly downregulated in spiral forms of H. pylori, while the gene expression was upregulated and + 30.3-fold changes was seen in coccoid forms of bacterium. To summarize, spoT gene is one of the key factors for antibiotic resistance and its enhanced expression in coccoid form can be a valuable diagnostic marker for recognition of H. pylori during morphological conversion.
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Affiliation(s)
- Farkhondeh Poursina
- Department of Microbiology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Jamshid Fagri
- Department of Microbiology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Nasrin Mirzaei
- Department of Microbiology, Tonekabon Branch, Islamic Azad University, Tonekabon, Iran
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Polyphosphate Kinase Antagonizes Virulence Gene Expression in Francisella tularensis. J Bacteriol 2018; 200:JB.00460-17. [PMID: 29158241 DOI: 10.1128/jb.00460-17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/02/2017] [Indexed: 12/31/2022] Open
Abstract
The alarmone ppGpp is a critical regulator of virulence gene expression in Francisella tularensis In this intracellular pathogen, ppGpp is thought to work in concert with the putative DNA-binding protein PigR and the SspA protein family members MglA and SspA to control a common set of genes. MglA and SspA form a complex that interacts with RNA polymerase (RNAP), and PigR functions by interacting with the RNAP-associated MglA-SspA complex. Prior work suggested that ppGpp indirectly exerts its regulatory effects in F. tularensis by promoting the accumulation of polyphosphate in the cell, which in turn was required for formation of the MglA-SspA complex. Here we show that in Escherichia coli, neither polyphosphate nor ppGpp is required for formation of the MglA-SspA complex but that ppGpp promotes the interaction between PigR and the MglA-SspA complex. Moreover, we show that polyphosphate kinase, the enzyme responsible for the synthesis of polyphosphate, antagonizes virulence gene expression in F. tularensis, a finding that is inconsistent with the notion that polyphosphate accumulation promotes virulence gene expression in this organism. Our findings identify polyphosphate kinase as a novel negative regulator of virulence gene expression in F. tularensis and support a model in which ppGpp exerts its positive regulatory effects by promoting the interaction between PigR and the MglA-SspA complex.IMPORTANCE In Francisella tularensis, MglA and SspA form a complex that associates with RNA polymerase to positively control the expression of key virulence genes. The MglA-SspA complex works together with the putative DNA-binding protein PigR and the alarmone ppGpp. PigR functions by interacting directly with the MglA-SspA complex, but how ppGpp exerts its effects was unclear. Prior work indicated that ppGpp acts by promoting the accumulation of polyphosphate, which is required for MglA and SspA to interact. Here we show that formation of the MglA-SspA complex does not require polyphosphate. Furthermore, we find that polyphosphate antagonizes the expression of virulence genes in F. tularensis Thus, ppGpp does not promote virulence gene expression in this organism through an effect on polyphosphate.
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15
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Chandrashekhar K, Kassem II, Nislow C, Gangaiah D, Candelero-Rueda RA, Rajashekara G. Transcriptome analysis of Campylobacter jejuni polyphosphate kinase (ppk1 and ppk2) mutants. Virulence 2015; 6:814-8. [PMID: 26537695 DOI: 10.1080/21505594.2015.1104449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Kshipra Chandrashekhar
- a Food Animal Health Research Program; Ohio Agricultural Research and Development Center; Department of Veterinary Preventive Medicine ; The Ohio State University ; Wooster , OH , USA
| | - Issmat I Kassem
- a Food Animal Health Research Program; Ohio Agricultural Research and Development Center; Department of Veterinary Preventive Medicine ; The Ohio State University ; Wooster , OH , USA
| | - Corey Nislow
- b Department of Pharmaceutical Sciences ; University of British Columbia ; Vancouver , BC Canada
| | - Dharanesh Gangaiah
- a Food Animal Health Research Program; Ohio Agricultural Research and Development Center; Department of Veterinary Preventive Medicine ; The Ohio State University ; Wooster , OH , USA
| | - Rosario A Candelero-Rueda
- a Food Animal Health Research Program; Ohio Agricultural Research and Development Center; Department of Veterinary Preventive Medicine ; The Ohio State University ; Wooster , OH , USA
| | - Gireesh Rajashekara
- a Food Animal Health Research Program; Ohio Agricultural Research and Development Center; Department of Veterinary Preventive Medicine ; The Ohio State University ; Wooster , OH , USA
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Positively-charged semi-tunnel is a structural and surface characteristic of polyphosphate-binding proteins: an in-silico study. PLoS One 2015; 10:e0123713. [PMID: 25879219 PMCID: PMC4400040 DOI: 10.1371/journal.pone.0123713] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 03/06/2015] [Indexed: 12/20/2022] Open
Abstract
Phosphate is essential for all major life processes, especially energy metabolism and signal transduction. A linear phosphate polymer, polyphosphate (polyP), linked by high-energy phosphoanhydride bonds, can interact with various proteins, playing important roles as an energy source and regulatory factor. However, polyP-binding structures are largely unknown. Here we proposed a putative polyP binding site, a positively-charged semi-tunnel (PCST), identified by surface electrostatics analyses in polyP kinases (PPKs) and many other polyP-related proteins. We found that the PCSTs in varied proteins were folded in different secondary structure compositions. Molecular docking calculations revealed a significant value for binding affinity to polyP in PCST-containing proteins. Utilizing the PCST identified in the β subunit of PPK3, we predicted the potential polyP-binding domain of PPK3. The discovery of this feature facilitates future searches for polyP-binding proteins and discovery of the mechanisms for polyP-binding activities. This should greatly enhance the understanding of the many physiological functions of protein-bound polyP and the involvement of polyP and polyP-binding proteins in various human diseases.
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17
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Norris V, Reusch RN, Igarashi K, Root-Bernstein R. Molecular complementarity between simple, universal molecules and ions limited phenotype space in the precursors of cells. Biol Direct 2014; 10:28. [PMID: 25470982 PMCID: PMC4264330 DOI: 10.1186/s13062-014-0028-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 11/24/2014] [Indexed: 01/29/2023] Open
Abstract
Background Fundamental problems faced by the protocells and their modern descendants include how to go from one phenotypic state to another; escape from a basin of attraction in the space of phenotypes; reconcile conflicting growth and survival strategies (and thereby live on ‘the scales of equilibria’); and create a coherent, reproducible phenotype from a multitude of constituents. Presentation of the hypothesis The solutions to these problems are likely to be found with the organic and inorganic molecules and inorganic ions that constituted protocells, which we term SUMIs for Simple Universal Molecules and Ions. These SUMIs probably included polyphosphate (PolyP) as a source of energy and of phosphate; poly-(R)-3-hydroxybutyrate (PHB) as a source of carbon and as a transporter in association with PolyP; polyamines as a source of nitrogen; lipids as precursors of membranes; as well as peptides, nucleic acids, and calcium. Here, we explore the hypothesis that the direct interactions between PHB, PolyP, polyamines and lipids – modulated by calcium – played a central role in solving the fundamental problems faced by early and modern cells. Testing the hypothesis We review evidence that SUMIs (1) were abundant and available to protocells; (2) are widespread in modern cells; (3) interact with one another and other cellular constituents to create structures with new functions surprisingly similar to those of proteins and RNA; (4) are essential to creating coherent phenotypes in modern bacteria. SUMIs are therefore natural candidates for reducing the immensity of phenotype space and making the transition from a “primordial soup” to living cells. Implications of the hypothesis We discuss the relevance of the SUMIs and their interactions to the ideas of molecular complementarity, composomes (molecular aggregates with hereditary properties based on molecular complementarity), and a prebiotic ecology of co-evolving populations of composomes. In particular, we propose that SUMIs might limit the initial phenotype space of composomes in a coherent way. As examples, we propose that acidocalcisomes arose from interactions and self-selection among SUMIs and that the phosphorylation of proteins in modern cells had its origin in the covalent modification of proteins by PHB. Reviewers This article was reviewed by Doron Lancet and Kepa Ruiz-Mirazo.
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18
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Borin BN, Tang W, Krezel AM. Helicobacter pylori RNA polymerase α-subunit C-terminal domain shows features unique to ɛ-proteobacteria and binds NikR/DNA complexes. Protein Sci 2014; 23:454-63. [PMID: 24442709 DOI: 10.1002/pro.2427] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 01/13/2014] [Accepted: 01/14/2014] [Indexed: 01/03/2023]
Abstract
Bacterial RNA polymerase is a large, multi-subunit enzyme responsible for transcription of genomic information. The C-terminal domain of the α subunit of RNA polymerase (αCTD) functions as a DNA and protein recognition element localizing the polymerase on certain promoter sequences and is essential in all bacteria. Although αCTD is part of RNA polymerase, it is thought to have once been a separate transcription factor, and its primary role is the recruitment of RNA polymerase to various promoters. Despite the conservation of the subunits of RNA polymerase among bacteria, the mechanisms of regulation of transcription vary significantly. We have determined the tertiary structure of Helicobacter pylori αCTD. It is larger than other structurally determined αCTDs due to an extra, highly amphipathic helix near the C-terminal end. Residues within this helix are highly conserved among ɛ-proteobacteria. The surface of the domain that binds A/T rich DNA sequences is conserved and showed binding to DNA similar to αCTDs of other bacteria. Using several NikR dependent promoter sequences, we observed cooperative binding of H. pylori αCTD to NikR:DNA complexes. We also produced αCTD lacking the 19 C-terminal residues, which showed greatly decreased stability, but maintained the core domain structure and binding affinity to NikR:DNA at low temperatures. The modeling of H. pylori αCTD into the context of transcriptional complexes suggests that the additional amphipathic helix mediates interactions with transcriptional regulators.
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Affiliation(s)
- Brendan N Borin
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, 37232
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19
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Wrench AP, Gardner CL, Siegel SD, Pagliai FA, Malekiha M, Gonzalez CF, Lorca GL. MglA/SspA complex interactions are modulated by inorganic polyphosphate. PLoS One 2013; 8:e76428. [PMID: 24116108 PMCID: PMC3792966 DOI: 10.1371/journal.pone.0076428] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 08/29/2013] [Indexed: 12/17/2022] Open
Abstract
The transcription factors MglA and SspA of Francisella tularensis form a heterodimer complex and interact with the RNA polymerase to regulate the expression of the Francisella pathogenicity island (FPI) genes. These genes are essential for this pathogen's virulence and survival within host cells. Our goal was to determine if an intracellular metabolite modulate these protein/protein interactions. In this study, we identified inorganic polyphosphate (polyP) as a signal molecule that promotes the interaction of MglA and SspA from F. tularensis SCHU S4. Analysis of the Mgla/SspA interaction was carried out using a two-hybrid system. The Escherichia coli reporter strain contained a deletion on the ppK-ppX operon, inhibiting polyP synthesis. The interaction between MglA and SspA was significantly impaired, as was the interaction between the MglA/SspA complex and the regulatory protein, FevR, indicating the stabilizing effect of polyP. In F. tularensis, chromatin immune precipitation studies revealed that in the absence of polyP, binding of the MglA/SspA complex to the promoter region of the pdpD, iglA, fevR and ppK genes is decreased. Isothermal titration calorimetry (ITC) indicated that polyP binds directly to the MglA/SspA complex with high affinity (KD = 0.3 µM). These observations directly correlated with results obtained from calorimetric scans (DSC), where a strong shift in the mid-transition temperature (Tm) of the MglA/SspA complex was observed in the presence of polyP.
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Affiliation(s)
- Algevis P. Wrench
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Christopher L. Gardner
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Sara D. Siegel
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Fernando A. Pagliai
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Mahsa Malekiha
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Claudio F. Gonzalez
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Graciela L. Lorca
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
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20
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Polyphosphate deficiency in Mycobacterium tuberculosis is associated with enhanced drug susceptibility and impaired growth in guinea pigs. J Bacteriol 2013; 195:2839-51. [PMID: 23585537 DOI: 10.1128/jb.00038-13] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Inorganic polyphosphate (polyP), a linear polymer of hundreds of phosphate residues linked by ATP-like phosphoanhydride bonds, is found in all organisms and performs a wide variety of functions. This study shows that polyP accumulation occurs in Mycobacterium tuberculosis upon exposure to various stress conditions. M. tuberculosis possesses a single homolog of ppk-1, and we have disrupted ppk-1 in the M. tuberculosis genome by allelic replacement. The mutant strain exhibited negligible levels of intracellular polyP, decreased expression of sigF and phoP, and reduced growth in the stationary phase and displayed a survival defect in response to nitrosative stress and in THP-1 macrophages compared to the wild-type strain. We report that reduction in polyP levels is associated with increased susceptibility of M. tuberculosis to certain TB drugs and impairs its ability to cause disease in guinea pigs. These results suggest that polyP contributes to persistence of M. tuberculosis in vitro and plays an important role in the physiology of bacteria residing within guinea pigs.
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21
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Fluorometric quantification of polyphosphate in environmental plankton samples: extraction protocols, matrix effects, and nucleic acid interference. Appl Environ Microbiol 2012; 79:273-81. [PMID: 23104409 DOI: 10.1128/aem.02592-12] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polyphosphate (polyP) is a ubiquitous biochemical with many cellular functions and comprises an important environmental phosphorus pool. However, methodological challenges have hampered routine quantification of polyP in environmental samples. We tested 15 protocols to extract inorganic polyphosphate from natural marine samples and cultured cyanobacteria for fluorometric quantification with 4',6-diamidino-2-phenylindole (DAPI) without prior purification. A combination of brief boiling and digestion with proteinase K was superior to all other protocols, including other enzymatic digestions and neutral or alkaline leaches. However, three successive extractions were required to extract all polyP. Standard addition revealed matrix effects that differed between sample types, causing polyP to be over- or underestimated by up to 50% in the samples tested here. Although previous studies judged that the presence of DNA would not complicate fluorometric quantification of polyP with DAPI, we show that RNA can cause significant interference at the wavelengths used to measure polyP. Importantly, treating samples with DNase and RNase before proteinase K digestion reduced fluorescence by up to 57%. We measured particulate polyP along a North Pacific coastal-to-open ocean transect and show that particulate polyP concentrations increased toward the open ocean. While our final method is optimized for marine particulate matter, different environmental sample types may need to be assessed for matrix effects, extraction efficiency, and nucleic acid interference.
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22
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Decker KB, James TD, Stibitz S, Hinton DM. The Bordetella pertussis model of exquisite gene control by the global transcription factor BvgA. MICROBIOLOGY-SGM 2012; 158:1665-1676. [PMID: 22628479 DOI: 10.1099/mic.0.058941-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bordetella pertussis causes whooping cough, an infectious disease that is reemerging despite widespread vaccination. A more complete understanding of B. pertussis pathogenic mechanisms will involve unravelling the regulation of its impressive arsenal of virulence factors. Here we review the action of the B. pertussis response regulator BvgA in the context of what is known about bacterial RNA polymerase and various modes of transcription activation. At most virulence gene promoters, multiple dimers of phosphorylated BvgA (BvgA~P) bind upstream of the core promoter sequence, using a combination of high- and low-affinity sites that fill through cooperativity. Activation by BvgA~P is typically mediated by a novel form of class I/II mechanisms, but two virulence genes, fim2 and fim3, which encode serologically distinct fimbrial subunits, are regulated using a previously unrecognized RNA polymerase/activator architecture. In addition, the fim genes undergo phase variation because of an extended cytosine (C) tract within the promoter sequences that is subject to slipped-strand mispairing during replication. These sophisticated systems of regulation demonstrate one aspect whereby B. pertussis, which is highly clonal and lacks the extensive genetic diversity observed in many other bacterial pathogens, has been highly successful as an obligate human pathogen.
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Affiliation(s)
- Kimberly B Decker
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tamara D James
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Scott Stibitz
- Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA
| | - Deborah M Hinton
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Yang ZX, Lu CY, Yang B, Xia N, Dou KF. PPK knockout attenuates evasion of immune elimination of Helicobacter pylori by macrophages. Shijie Huaren Xiaohua Zazhi 2012; 20:22-26. [DOI: 10.11569/wcjd.v20.i1.22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To evaluate the impact of knockout of the polyphosphate kinase gene in Helicobacter pylori (H. pylori) on bacterial evasion of immune elimination by macrophages.
METHODS: A PPK null mutant of H. pylori was constructed by gene homologous recombination. The polyphosphate was extracted from the PPK null mutant and wild type bacteria to compare the amount of polyphosphate by conversion into ATP. PPK null mutant H. pylori or wild type bacteria were co-cultured with murine macrophage cell line Raw 264.1 to compare the bacterial survival in macrophages at 24 h.
RESULTS: A PPK null mutant H. pylori strain was successfully constructed. The amount of polyphosphate in PPK null mutant bacteria was significantly lower than that in wild type bacteria (0.46 nmol Pi/mg Protein ± 0.25 nmol Pi/mg Protein vs 175.33 nmol Pi/mg Protein ± 21.22 nmol Pi/mg Protein, P < 0.01). Compared to wild type H. pylori, the survival rate of PPK null mutant bacteria in macrophages was similar at 2 h but was significantly reduced at 24 h.
CONCLUSION: PPK plays a critical role in synthesizing polyphosphate in H. pylori. PPK knockout in H. pylori significantly impaired their ability to synthesize polyphosphate and to evade immune elimination by macrophages.
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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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Parker H, Keenan JI. Composition and function of Helicobacter pylori outer membrane vesicles. Microbes Infect 2011; 14:9-16. [PMID: 21911076 DOI: 10.1016/j.micinf.2011.08.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 08/07/2011] [Accepted: 08/09/2011] [Indexed: 01/26/2023]
Abstract
The gastric pathogen Helicobacter pylori sheds outer membrane vesicles (OMV) that possess many of the surface elements of the bacterium. Here we review current knowledge on the composition of H. pylori OMV and discuss evidence for their potential roles in bacterial survival and pathogenesis.
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Affiliation(s)
- Heather Parker
- Department of Pathology, University of Otago, PO Box 4345, Christchurch, New Zealand
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26
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Abstract
Growth rate regulation in bacteria has been an important issue in bacterial physiology for the past 50 years. This review, using Escherichia coli as a paradigm, summarizes the mechanisms for the regulation of rRNA synthesis in the context of systems biology, particularly, in the context of genome-wide competition for limited RNA polymerase (RNAP) in the cell under different growth conditions including nutrient starvation. The specific location of the seven rrn operons in the chromosome and the unique properties of the rrn promoters contribute to growth rate regulation. The length of the rrn transcripts, coupled with gene dosage effects, influence the distribution of RNAP on the chromosome in response to growth rate. Regulation of rRNA synthesis depends on multiple factors that affect the structure of the nucleoid and the allocation of RNAP for global gene expression. The magic spot ppGpp, which acts with DksA synergistically, is a key effector in both the growth rate regulation and the stringent response induced by nutrient starvation, mainly because the ppGpp level changes in response to environmental cues. It regulates rRNA synthesis via a cascade of events including both transcription initiation and elongation, and can be explained by an RNAP redistribution (allocation) model.
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Affiliation(s)
- Ding Jun Jin
- Transcription Control Section, Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute-Frederick, National Institutes of Health, Frederick, MD, USA.
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