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Chamlagain M, Hu J, Sionov RV, Steinberg D. Anti-bacterial and anti-biofilm activities of arachidonic acid against the cariogenic bacterium Streptococcus mutans. Front Microbiol 2024; 15:1333274. [PMID: 38596377 PMCID: PMC11002910 DOI: 10.3389/fmicb.2024.1333274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 02/16/2024] [Indexed: 04/11/2024] Open
Abstract
Streptococcus mutans is a Gram-positive, facultative anaerobic bacterium, which causes dental caries after forming biofilms on the tooth surface while producing organic acids that demineralize enamel and dentin. We observed that the polyunsaturated arachidonic acid (AA) (ω-6; 20:4) had an anti-bacterial activity against S. mutans, which prompted us to investigate its mechanism of action. The minimum inhibitory concentration (MIC) of AA on S. mutans was 25 μg/ml in the presence of 5% CO2, while it was reduced to 6.25-12.5 μg/ml in the absence of CO2 supplementation. The anti-bacterial action was due to a combination of bactericidal and bacteriostatic effects. The minimum biofilm inhibitory concentration (MBIC) was the same as the MIC, suggesting that part of the anti-biofilm effect was due to the anti-bacterial activity. Gene expression studies showed decreased expression of biofilm-related genes, suggesting that AA also has a specific anti-biofilm effect. Flow cytometric analyses using potentiometric DiOC2(3) dye, fluorescent efflux pump substrates, and live/dead SYTO 9/propidium iodide staining showed that AA leads to immediate membrane hyperpolarization, altered membrane transport and efflux pump activities, and increased membrane permeability with subsequent membrane perforation. High-resolution scanning electron microscopy (HR-SEM) showed remnants of burst bacteria. Furthermore, flow cytometric analysis using the redox probe 2',7'-dichlorofluorescein diacetate (DCFHDA) showed that AA acts as an antioxidant in a dose-dependent manner. α-Tocopherol, an antioxidant that terminates the radical chain, counteracted the anti-bacterial activity of AA, suggesting that oxidation of AA in bacteria leads to the production of cytotoxic radicals that contribute to bacterial growth arrest and death. Importantly, AA was not toxic to normal Vero epithelial cells even at 100 μg/ml, and it did not cause hemolysis of erythrocytes. In conclusion, our study shows that AA is a potentially safe drug that can be used to reduce the bacterial burden of cariogenic S. mutans.
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Affiliation(s)
- Manoj Chamlagain
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Jieni Hu
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ronit Vogt Sionov
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Doron Steinberg
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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2
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Goncheva MI, Chin D, Heinrichs DE. Nucleotide biosynthesis: the base of bacterial pathogenesis. Trends Microbiol 2022; 30:793-804. [PMID: 35074276 DOI: 10.1016/j.tim.2021.12.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 01/08/2023]
Abstract
Most free-living organisms require the synthesis and/or acquisition of purines and pyrimidines, which form the basis of nucleotides, to survive. In most bacteria, the nucleotides are synthesized de novo and the products are used in many cell functions, including DNA replication, energy storage, and as signaling molecules. Due to their central role in the metabolism of bacteria, both nucleotide biosynthesis pathways have strong links with the virulence of opportunistic and bona fide bacterial pathogens. Recent findings have established a new, shared link in the control of nucleotide biosynthesis and the production of virulence factors. Furthermore, targeting of these pathways forms the basis of interspecies competition and can provide an open source for new antimicrobial compounds. Here, we highlight the contribution of nucleotide biosynthesis to bacterial pathogenesis in a plethora of different diseases and speculate on how they can be targeted by intervention strategies.
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Affiliation(s)
- Mariya I Goncheva
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1
| | - Denny Chin
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1
| | - David E Heinrichs
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1.
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Thornburg ZR, Bianchi DM, Brier TA, Gilbert BR, Earnest TM, Melo MC, Safronova N, Sáenz JP, Cook AT, Wise KS, Hutchison CA, Smith HO, Glass JI, Luthey-Schulten Z. Fundamental behaviors emerge from simulations of a living minimal cell. Cell 2022; 185:345-360.e28. [PMID: 35063075 PMCID: PMC9985924 DOI: 10.1016/j.cell.2021.12.025] [Citation(s) in RCA: 60] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/01/2021] [Accepted: 12/17/2021] [Indexed: 01/18/2023]
Abstract
We present a whole-cell fully dynamical kinetic model (WCM) of JCVI-syn3A, a minimal cell with a reduced genome of 493 genes that has retained few regulatory proteins or small RNAs. Cryo-electron tomograms provide the cell geometry and ribosome distributions. Time-dependent behaviors of concentrations and reaction fluxes from stochastic-deterministic simulations over a cell cycle reveal how the cell balances demands of its metabolism, genetic information processes, and growth, and offer insight into the principles of life for this minimal cell. The energy economy of each process including active transport of amino acids, nucleosides, and ions is analyzed. WCM reveals how emergent imbalances lead to slowdowns in the rates of transcription and translation. Integration of experimental data is critical in building a kinetic model from which emerges a genome-wide distribution of mRNA half-lives, multiple DNA replication events that can be compared to qPCR results, and the experimentally observed doubling behavior.
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Affiliation(s)
- Zane R. Thornburg
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - David M. Bianchi
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Troy A. Brier
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Benjamin R. Gilbert
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Tyler M. Earnest
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Marcelo C.R. Melo
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Nataliya Safronova
- Technische Universität Dresden, B CUBE Center for Molecular Bioengineering, 01307 Dresden, Germany
| | - James P. Sáenz
- Technische Universität Dresden, B CUBE Center for Molecular Bioengineering, 01307 Dresden, Germany
| | | | - Kim S. Wise
- J. Craig Venter Institute, La Jolla, CA 92037, USA
| | | | | | | | - Zaida Luthey-Schulten
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; NSF Center for the Physics of Living Cells, Urbana, IL 61801, USA; NIH Center for Macromolecular Modeling and Bioinformatics, Urbana, IL 61801, USA.
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Puccio T, Misra BB, Kitten T. Time-course analysis of Streptococcus sanguinis after manganese depletion reveals changes in glycolytic and nucleic acid metabolites. Metabolomics 2021; 17:44. [PMID: 33893555 PMCID: PMC8064989 DOI: 10.1007/s11306-021-01795-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 04/13/2021] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Manganese is important for the endocarditis pathogen Streptococcus sanguinis. Little is known about why manganese is required for virulence or how it impacts the metabolome of streptococci. OBJECTIVES We applied untargeted metabolomics to cells and media to understand temporal changes resulting from manganese depletion. METHODS EDTA was added to a S. sanguinis manganese-transporter mutant in aerobic fermentor conditions. Cell and media samples were collected pre- and post-EDTA treatment. Metabolomics data were generated using positive and negative modes of data acquisition on an LC-MS/MS system. Data were subjected to statistical processing using MetaboAnalyst and time-course analysis using Short Time series Expression Miner (STEM). Recombinant enzymes were assayed for metal dependence. RESULTS We observed quantitative changes in 534 and 422 metabolites in cells and media, respectively, after EDTA addition. The 173 cellular metabolites identified as significantly different indicated enrichment of purine and pyrimidine metabolism. Further multivariate analysis revealed that the top 15 cellular metabolites belonged primarily to lipids and redox metabolites. The STEM analysis revealed global changes in cells and media in comparable metabolic pathways. Glycolytic intermediates such as fructose-1,6-bisphosphate increased, suggesting that enzymes that utilize them require manganese for activity or expression. Recombinant enzymes were confirmed to utilize manganese in vitro. Nucleosides accumulated, possibly due to a blockage in conversion to nucleobases resulting from manganese-dependent regulation. CONCLUSION Differential analysis of metabolites revealed the activation of a number of metabolic pathways in response to manganese depletion, many of which are connected to carbon catabolite repression.
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Affiliation(s)
- Tanya Puccio
- Philips Institute for Oral Health Research, Virginia Commonwealth University School of Dentistry, Richmond, VA, 23298, USA
| | - Biswapriya B Misra
- Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, 27157, USA
| | - Todd Kitten
- Philips Institute for Oral Health Research, Virginia Commonwealth University School of Dentistry, Richmond, VA, 23298, USA.
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Abdullah MR, Batuecas MT, Jennert F, Voß F, Westhoff P, Kohler TP, Molina R, Hirschmann S, Lalk M, Hermoso JA, Hammerschmidt S. Crystal Structure and Pathophysiological Role of the Pneumococcal Nucleoside-binding Protein PnrA. J Mol Biol 2020; 433:166723. [PMID: 33242497 DOI: 10.1016/j.jmb.2020.11.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/15/2020] [Accepted: 11/18/2020] [Indexed: 10/22/2022]
Abstract
Nucleotides are important for RNA and DNA synthesis and, despite a de novo synthesis by bacteria, uptake systems are crucial. Streptococcus pneumoniae, a facultative human pathogen, produces a surface-exposed nucleoside-binding protein, PnrA, as part of an ABC transporter system. Here we demonstrate the binding affinity of PnrA to nucleosides adenosine, guanosine, cytidine, thymidine and uridine by microscale thermophoresis and indicate the consumption of adenosine and guanosine by 1H NMR spectroscopy. In a series of five crystal structures we revealed the PnrA structure and provide insights into how PnrA can bind purine and pyrimidine ribonucleosides but with preference for purine ribonucleosides. Crystal structures of PnrA:nucleoside complexes unveil a clear pattern of interactions in which both the N- and C- domains of PnrA contribute. The ribose moiety is strongly recognized through a conserved network of H-bond interactions, while plasticity in loop 27-36 is essential to bind purine- or pyrimidine-based nucleosides. Further, we deciphered the role of PnrA in pneumococcal fitness in infection experiments. Phagocytosis experiments did not show a clear difference in phagocytosis between PnrA-deficient and wild-type pneumococci. In the acute pneumonia infection model the deficiency of PnrA attenuated moderately virulence of the mutant, which is indicated by a delay in the development of severe lung infections. Importantly, we confirmed the loss of fitness in co-infections, where the wild-type out-competed the pnrA-mutant. In conclusion, we present the PnrA structure in complex with individual nucleosides and show that the consumption of adenosine and guanosine under infection conditions is required for virulence.
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Affiliation(s)
- Mohammed R Abdullah
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Center for Functional Genomics of Microbes, University of Greifswald, D-17487 Greifswald, Germany; Present Address: Institut für Klinische Chemie und Laboratoriumsmedizin, Universitätsmedizin Greifswald, Germany
| | - María T Batuecas
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry "Rocasolano", CSIC, 28006 Madrid, Spain
| | - Franziska Jennert
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Center for Functional Genomics of Microbes, University of Greifswald, D-17487 Greifswald, Germany; Present Address: Institute for Microbiology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Franziska Voß
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Center for Functional Genomics of Microbes, University of Greifswald, D-17487 Greifswald, Germany
| | - Philipp Westhoff
- Cellular Metabolism/Metabolomics, Institute of Biochemistry, University of Greifswald, D-17487 Greifswald, Germany; Present Address: Biochemie der Pflanzen, Heinrich-Heine-Universität Düsseldorf, Germany
| | - Thomas P Kohler
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Center for Functional Genomics of Microbes, University of Greifswald, D-17487 Greifswald, Germany
| | - Rafael Molina
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry "Rocasolano", CSIC, 28006 Madrid, Spain; Present Address: Structural Molecular Biology Group, Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences University of Copenhagen, Blegdamsvej 3-B, Copenhagen, 2200, Denmark
| | - Stephanie Hirschmann
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Center for Functional Genomics of Microbes, University of Greifswald, D-17487 Greifswald, Germany
| | - Michael Lalk
- Cellular Metabolism/Metabolomics, Institute of Biochemistry, University of Greifswald, D-17487 Greifswald, Germany
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry "Rocasolano", CSIC, 28006 Madrid, Spain.
| | - Sven Hammerschmidt
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Center for Functional Genomics of Microbes, University of Greifswald, D-17487 Greifswald, Germany.
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Chandravanshi M, Sharma A, Dasgupta P, Mandal SK, Kanaujia SP. Identification and characterization of ABC transporters for carbohydrate uptake in Thermus thermophilus HB8. Gene 2019; 696:135-148. [DOI: 10.1016/j.gene.2019.02.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 02/01/2019] [Indexed: 02/06/2023]
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7
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Breuer M, Earnest TM, Merryman C, Wise KS, Sun L, Lynott MR, Hutchison CA, Smith HO, Lapek JD, Gonzalez DJ, de Crécy-Lagard V, Haas D, Hanson AD, Labhsetwar P, Glass JI, Luthey-Schulten Z. Essential metabolism for a minimal cell. eLife 2019; 8:36842. [PMID: 30657448 PMCID: PMC6609329 DOI: 10.7554/elife.36842] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 01/17/2019] [Indexed: 11/29/2022] Open
Abstract
JCVI-syn3A, a robust minimal cell with a 543 kbp genome and 493 genes, provides a versatile platform to study the basics of life. Using the vast amount of experimental information available on its precursor, Mycoplasma mycoides capri, we assembled a near-complete metabolic network with 98% of enzymatic reactions supported by annotation or experiment. The model agrees well with genome-scale in vivo transposon mutagenesis experiments, showing a Matthews correlation coefficient of 0.59. The genes in the reconstruction have a high in vivo essentiality or quasi-essentiality of 92% (68% essential), compared to 79% in silico essentiality. This coherent model of the minimal metabolism in JCVI-syn3A at the same time also points toward specific open questions regarding the minimal genome of JCVI-syn3A, which still contains many genes of generic or completely unclear function. In particular, the model, its comparison to in vivo essentiality and proteomics data yield specific hypotheses on gene functions and metabolic capabilities; and provide suggestions for several further gene removals. In this way, the model and its accompanying data guide future investigations of the minimal cell. Finally, the identification of 30 essential genes with unclear function will motivate the search for new biological mechanisms beyond metabolism. One way that researchers can test whether they understand a biological system is to see if they can accurately recreate it as a computer model. The more they learn about living things, the more the researchers can improve their models and the closer the models become to simulating the original. In this approach, it is best to start by trying to model a simple system. Biologists have previously succeeded in creating ‘minimal bacterial cells’. These synthetic cells contain fewer genes than almost all other living things and they are believed to be among the simplest possible forms of life that can grow on their own. The minimal cells can produce all the chemicals that they need to survive – in other words, they have a metabolism. Accurately recreating one of these cells in a computer is a key first step towards simulating a complete living system. Breuer et al. have developed a computer model to simulate the network of the biochemical reactions going on inside a minimal cell with just 493 genes. By altering the parameters of their model and comparing the results to experimental data, Breuer et al. explored the accuracy of their model. Overall, the model reproduces experimental results, but it is not yet perfect. The differences between the model and the experiments suggest new questions and tests that could advance our understanding of biology. In particular, Breuer et al. identified 30 genes that are essential for life in these cells but that currently have no known purpose. Continuing to develop and expand models like these to reproduce more complex living systems provides a tool to test current knowledge of biology. These models may become so advanced that they could predict how living things will respond to changing situations. This would allow scientists to test ideas sooner and make much faster progress in understanding life on Earth. Ultimately, these models could one day help to accelerate medical and industrial processes to save lives and enhance productivity.
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Affiliation(s)
- Marian Breuer
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Tyler M Earnest
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, United States
| | | | - Kim S Wise
- J Craig Venter Institute, La Jolla, United States
| | - Lijie Sun
- J Craig Venter Institute, La Jolla, United States
| | | | | | | | - John D Lapek
- Department of Pharmacology and School of Pharmacy, University of California at San Diego, La Jolla, United States
| | - David J Gonzalez
- Department of Pharmacology and School of Pharmacy, University of California at San Diego, La Jolla, United States
| | - Valérie de Crécy-Lagard
- Department of Microbiology and Cell Science, University of Florida, Gainesville, United States
| | - Drago Haas
- Department of Microbiology and Cell Science, University of Florida, Gainesville, United States
| | - Andrew D Hanson
- Horticultural Sciences Department, University of Florida, Gainesville, United States
| | - Piyush Labhsetwar
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, United States
| | - John I Glass
- J Craig Venter Institute, La Jolla, United States
| | - Zaida Luthey-Schulten
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, United States
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8
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Functional metagenomics identifies novel genes ABCTPP, TMSRP1 and TLSRP1 among human gut enterotypes. Sci Rep 2018; 8:1397. [PMID: 29362424 PMCID: PMC5780487 DOI: 10.1038/s41598-018-19862-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 01/09/2018] [Indexed: 01/08/2023] Open
Abstract
Every niche in the biosphere is touched by the seemingly endless capacity of microbes to transform the world around them by adapting swiftly and flexibly to the environmental changes, likewise the gastrointestinal tract is no exception. The ability to cope with rapid changes in external osmolarity is an important aspect of gut microbes for their survival and colonization. Identification of these survival mechanisms is a pivotal step towards understanding genomic suitability of a symbiont for successful human gut colonization. Here we highlight our recent work applying functional metagenomics to study human gut microbiome to identify candidate genes responsible for the salt stress tolerance. A plasmid borne metagenomic library of Bacteroidetes enriched human fecal metagenomic DNA led to identification of unique salt osmotolerance clones SR6 and SR7. Subsequent gene analysis combined with functional studies revealed that TLSRP1 within pSR7 and TMSRP1 and ABCTPP of pSR6 are the active loci responsible for osmotolerance through an energy dependent mechanism. Our study elucidates the novel genetic machinery involved in bestowing osmotolerance in Prevotella and Bacteroidetes, the predominant microbial groups in a North Indian population. This study unravels an alternative method for imparting ionic stress tolerance, which may be prevalent in the human gut microbiome.
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Kohler S, Voß F, Gómez Mejia A, Brown JS, Hammerschmidt S. Pneumococcal lipoproteins involved in bacterial fitness, virulence, and immune evasion. FEBS Lett 2016; 590:3820-3839. [DOI: 10.1002/1873-3468.12352] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 08/01/2016] [Accepted: 08/05/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Sylvia Kohler
- Department Genetics of Microorganisms; Interfaculty Institute for Genetics and Functional Genomics; University of Greifswald; Germany
| | - Franziska Voß
- Department Genetics of Microorganisms; Interfaculty Institute for Genetics and Functional Genomics; University of Greifswald; Germany
| | - Alejandro Gómez Mejia
- Department Genetics of Microorganisms; Interfaculty Institute for Genetics and Functional Genomics; University of Greifswald; Germany
| | - Jeremy S. Brown
- Department of Medicine; Centre for Inflammation and Tissue Repair; University College Medical School; London UK
| | - Sven Hammerschmidt
- Department Genetics of Microorganisms; Interfaculty Institute for Genetics and Functional Genomics; University of Greifswald; Germany
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Karlskås IL, Eijsink VGH, Saleihan Z, Holo H, Mathiesen G. EF0176 and EF0177 from Enterococcus faecalis V583 are substrate-binding lipoproteins involved in ABC transporter mediated ribonucleoside uptake. Microbiology (Reading) 2015; 161:754-64. [DOI: 10.1099/mic.0.000045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 01/26/2015] [Indexed: 12/12/2022] Open
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11
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Saxena S, Khan N, Dehinwal R, Kumar A, Sehgal D. Conserved surface accessible nucleoside ABC transporter component SP0845 is essential for pneumococcal virulence and confers protection in vivo. PLoS One 2015; 10:e0118154. [PMID: 25689507 PMCID: PMC4331430 DOI: 10.1371/journal.pone.0118154] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 01/05/2015] [Indexed: 11/30/2022] Open
Abstract
Streptococcus pneumoniae is a leading cause of bacterial pneumonia, sepsis and meningitis. Surface accessible proteins of S. pneumoniae are being explored for the development of a protein-based vaccine in order to overcome the limitations of existing polysaccharide-based pneumococcal vaccines. To identify a potential vaccine candidate, we resolved surface-associated proteins of S. pneumoniae TIGR4 strain using two-dimensional gel electrophoresis followed by immunoblotting with antisera generated against whole heat-killed TIGR4. Ten immunoreactive spots were identified by mass spectrometric analysis that included a putative lipoprotein SP0845. Analysis of the inferred amino acid sequence of sp0845 homologues from 36 pneumococcal strains indicated that SP0845 was highly conserved (>98% identity) and showed less than 11% identity with any human protein. Our bioinformatic and functional analyses demonstrated that SP0845 is the substrate-binding protein of an ATP-binding cassette (ABC) transporter that is involved in nucleoside uptake with cytidine, uridine, guanosine and inosine as the preferred substrates. Deletion of the gene encoding SP0845 renders pneumococci avirulent suggesting that it is essential for virulence. Immunoblot analysis suggested that SP0845 is expressed in in vitro grown pneumococci and during mice infection. Immunofluorescence microscopy and flow cytometry data indicated that SP0845 is surface exposed in encapsulated strains and accessible to antibodies. Subcutaneous immunization with recombinant SP0845 induced high titer antibodies in mice. Hyperimmune sera raised against SP0845 promoted killing of encapsulated pneumococcal strains in a blood bactericidal assay. Immunization with SP0845 protected mice from intraperitoneal challenge with heterologous pneumococcal serotypes. Based on its surface accessibility, role in virulence and ability to elicit protective immunity, we propose that SP0845 may be a potential candidate for a protein-based pneumococcal vaccine.
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Affiliation(s)
- Sneha Saxena
- Molecular Immunology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Naeem Khan
- Molecular Immunology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Ruchika Dehinwal
- Molecular Immunology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Ajay Kumar
- Molecular Immunology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Devinder Sehgal
- Molecular Immunology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
- * E-mail:
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Li F, Liang J, Wang W, Zhou X, Deng Z, Wang Z. Two nucleoside receptors from Streptomyces coelicolor: expression of the genes and characterization of the recombinant proteins. Protein Expr Purif 2015; 109:40-6. [PMID: 25680770 DOI: 10.1016/j.pep.2015.02.004] [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: 10/28/2014] [Revised: 01/06/2015] [Accepted: 02/03/2015] [Indexed: 11/19/2022]
Abstract
Streptomyces coelicolor is a soil-dwelling bacterium that undergoes an intricate, saprophytic lifecycle. The bacterium takes up exogenous nucleosides for nucleic acid synthesis or use as carbon and energy sources. However, nucleosides must pass through the membrane with the help of transporters. In the present work, the SCO4884 and SCO4885 genes were cloned into pCOLADuet-1 and overexpressed in Escherichia coli BL21. Each protein was monomeric. Using isothermal titration calorimetry, we determined that SCO4884 and SCO4885 are likely nucleoside receptors with affinity for adenosine and pyrimidine nucleosides. On the basis of bioinformatics analysis and the transporter classification system, we speculate that SCO4884-SCO4888 is an ABC-like transporter responsible for the uptake of adenosine and pyrimidine nucleosides.
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Affiliation(s)
- Fuhou Li
- State Key Laboratory of Microbial Metabolism, School of Life Science & Biotechnology, Shanghai Jiaotong University, Shanghai 200030, People's Republic of China; School of Marine Science and Technology, Jiangsu Marine Resources Development Research Institute, Huaihai Institute of Technology, Lianyungang, Jiangsu Province 222005, People's Republic of China
| | - Jingdan Liang
- State Key Laboratory of Microbial Metabolism, School of Life Science & Biotechnology, Shanghai Jiaotong University, Shanghai 200030, People's Republic of China
| | - Weixia Wang
- School of Marine Science and Technology, Jiangsu Marine Resources Development Research Institute, Huaihai Institute of Technology, Lianyungang, Jiangsu Province 222005, People's Republic of China
| | - Xiufen Zhou
- State Key Laboratory of Microbial Metabolism, School of Life Science & Biotechnology, Shanghai Jiaotong University, Shanghai 200030, People's Republic of China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, School of Life Science & Biotechnology, Shanghai Jiaotong University, Shanghai 200030, People's Republic of China.
| | - Zhijun Wang
- State Key Laboratory of Microbial Metabolism, School of Life Science & Biotechnology, Shanghai Jiaotong University, Shanghai 200030, People's Republic of China.
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Bidossi A, Mulas L, Decorosi F, Colomba L, Ricci S, Pozzi G, Deutscher J, Viti C, Oggioni MR. A functional genomics approach to establish the complement of carbohydrate transporters in Streptococcus pneumoniae. PLoS One 2012; 7:e33320. [PMID: 22428019 PMCID: PMC3302838 DOI: 10.1371/journal.pone.0033320] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 02/10/2012] [Indexed: 01/02/2023] Open
Abstract
The aerotolerant anaerobe Streptococcus pneumoniae is part of the normal nasopharyngeal microbiota of humans and one of the most important invasive pathogens. A genomic survey allowed establishing the occurrence of twenty-one phosphotransferase systems, seven carbohydrate uptake ABC transporters, one sodium:solute symporter and a permease, underlining an exceptionally high capacity for uptake of carbohydrate substrates. Despite high genomic variability, combined phenotypic and genomic analysis of twenty sequenced strains did assign the substrate specificity only to two uptake systems. Systematic analysis of mutants for most carbohydrate transporters enabled us to assign a phenotype and substrate specificity to twenty-three transport systems. For five putative transporters for galactose, pentoses, ribonucleosides and sulphated glycans activity was inferred, but not experimentally confirmed and only one transport system remains with an unknown substrate and lack of any functional annotation. Using a metabolic approach, 80% of the thirty-two fermentable carbon substrates were assigned to the corresponding transporter. The complexity and robustness of sugar uptake is underlined by the finding that many transporters have multiple substrates, and many sugars are transported by more than one system. The present work permits to draw a functional map of the complete arsenal of carbohydrate utilisation proteins of pneumococci, allows re-annotation of genomic data and might serve as a reference for related species. These data provide tools for specific investigation of the roles of the different carbon substrates on pneumococcal physiology in the host during carriage and invasive infection.
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Affiliation(s)
- Alessandro Bidossi
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Laura Mulas
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Francesca Decorosi
- Sezione Microbiologia, Dip. Biotecnologie Agrarie, Università degli Studi di Firenze, Firenze, Italy
| | - Leonarda Colomba
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Susanna Ricci
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Gianni Pozzi
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
- UOC Batteriologia, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | | | - Carlo Viti
- Sezione Microbiologia, Dip. Biotecnologie Agrarie, Università degli Studi di Firenze, Firenze, Italy
| | - Marco Rinaldo Oggioni
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
- UOC Batteriologia, Azienda Ospedaliera Universitaria Senese, Siena, Italy
- * E-mail:
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Hicks MA, Barber AE, Giddings LA, Caldwell J, O’Connor SE, Babbitt PC. The evolution of function in strictosidine synthase-like proteins. Proteins 2011; 79:3082-98. [PMID: 21948213 PMCID: PMC3561908 DOI: 10.1002/prot.23135] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 06/22/2011] [Accepted: 07/07/2011] [Indexed: 01/23/2023]
Abstract
The exponential growth of sequence data provides abundant information for the discovery of new enzyme reactions. Correctly annotating the functions of highly diverse proteins can be difficult, however, hindering use of this information. Global analysis of large superfamilies of related proteins is a powerful strategy for understanding the evolution of reactions by identifying catalytic commonalities and differences in reaction and substrate specificity, even when only a few members have been biochemically or structurally characterized. A comparison of >2500 sequences sharing the six-bladed β-propeller fold establishes sequence, structural, and functional links among the three subgroups of the functionally diverse N6P superfamily: the arylesterase-like and senescence marker protein-30/gluconolactonase/luciferin-regenerating enzyme-like (SGL) subgroups, representing enzymes that catalyze lactonase and related hydrolytic reactions, and the so-called strictosidine synthase-like (SSL) subgroup. Metal-coordinating residues were identified as broadly conserved in the active sites of all three subgroups except for a few proteins from the SSL subgroup, which have been experimentally determined to catalyze the quite different strictosidine synthase (SS) reaction, a metal-independent condensation reaction. Despite these differences, comparison of conserved catalytic features of the arylesterase-like and SGL enzymes with the SSs identified similar structural and mechanistic attributes between the hydrolytic reactions catalyzed by the former and the condensation reaction catalyzed by SS. The results also suggest that despite their annotations, the great majority of these >500 SSL sequences do not catalyze the SS reaction; rather, they likely catalyze hydrolytic reactions typical of the other two subgroups instead. This prediction was confirmed experimentally for one of these proteins.
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Affiliation(s)
- Michael A. Hicks
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, Box 2550, 1700 Fourth Street, San Francisco, California 94158
| | - Alan E. Barber
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, Box 2550, 1700 Fourth Street, San Francisco, California 94158
| | - Lesley-Ann Giddings
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Jenna Caldwell
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Sarah E. O’Connor
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Patricia C. Babbitt
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, Box 2550, 1700 Fourth Street, San Francisco, California 94158
- Department of Pharmaceutical Chemistry, UCSF
- California Institute for Quantitative Biosciences, UCSF
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Surface lipoprotein PpiA of Streptococcus mutans suppresses scavenger receptor MARCO-dependent phagocytosis by macrophages. Infect Immun 2011; 79:4933-40. [PMID: 21986627 DOI: 10.1128/iai.05693-11] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Streptococcus mutans is associated with the initiation and progression of human dental caries and is occasionally isolated from the blood of patients with bacteremia and infective endocarditis. For the pathogen to survive in the infected host, surface lipoproteins of S. mutans are likely to play important roles in interactions with the innate immune system. To clarify the role that a putative lipoprotein, peptidyl-prolyl cis/trans-isomerase (PpiA), of S. mutans plays in the macrophage response, we investigated the response of THP-1-derived macrophages to S. mutans challenge. The deletion of the gene encoding Lgt eliminated PpiA on the cell surface of S. mutans, which implies that PpiA is a lipoprotein that is lipid anchored in the cell membrane by Lgt. Human and murine peritoneal macrophages both showed higher phagocytic activities for the ppiA and lgt mutants than the wild type, which indicates that the presence of PpiA reduces S. mutans phagocytosis. In addition, infection with S. mutans markedly induced mRNAs of macrophage receptor with collagenous structure (MARCO) and scavenger receptor A (SR-A) in human macrophages. In particular, transcriptional and translational levels of MARCO in human macrophages infected with the ppiA mutant were higher than those in macrophages infected with the wild type. Phagocytosis of S. mutans by human macrophages markedly decreased after treatment with anti-MARCO IgG. These results demonstrate that the S. mutans lipoprotein PpiA contributes to suppression of MARCO-mediated phagocytosis of this bacterium by macrophages.
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Abstract
CodY is a global transcriptional regulator known to control expression of more than 100 genes and operons in Bacillus subtilis. Some of the most strongly repressed targets of CodY, the nupNOPQ (formerly, yufNOPQ) genes, were found to encode a guanosine transporter. Using DNase I footprinting experiments, we identified two high-affinity CodY-binding sites in the regulatory region of the nupN gene. The two sites are located 50 bp upstream and 163 bp downstream of the transcription start site. The downstream site was responsible for 6- to 8-fold nupN repression in the absence of the upstream site. When the upstream site was intact, however, only a minor contribution of the downstream site to nupN regulation could be detected under the conditions tested. Both sites contained 15-bp CodY-binding motifs with two mismatches each with respect to the consensus sequence, AATTTTCWGTTTTAA. However, the experimentally determined binding sites included additional sequences flanking the 15-bp CodY-binding motifs. An additional version of the 15-bp CodY-binding motif, with 5 mismatches with respect to the consensus but essential for efficient regulation by CodY, was found within the upstream site. The presence of multiple 15-bp motifs may be a common feature of CodY-binding sites.
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Eitinger T, Rodionov DA, Grote M, Schneider E. Canonical and ECF-type ATP-binding cassette importers in prokaryotes: diversity in modular organization and cellular functions. FEMS Microbiol Rev 2011; 35:3-67. [PMID: 20497229 DOI: 10.1111/j.1574-6976.2010.00230.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Affiliation(s)
- Thomas Eitinger
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
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18
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Martinussen J, Sørensen C, Jendresen CB, Kilstrup M. Two nucleoside transporters in Lactococcus lactis with different substrate specificities. MICROBIOLOGY-SGM 2010; 156:3148-3157. [PMID: 20595258 DOI: 10.1099/mic.0.039818-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In an alternative to biosynthesis of nucleotides, most organisms are capable of exploiting exogenous nucleotide sources. In order to do so, the nucleotide precursors must pass the membrane, which requires the presence of transporters. Normally, phosphorylated compounds are not subject to transport, and the utilization of nucleotides is dependent on exogenous phosphatases. The composition of transporters with specificity for purine and pyrimidine nucleosides and nucleobases is subject to variation. The ability of Lactococcus lactis to transport different nucleosides across the cell membrane was characterized at both genetic and physiological level, using mutagenesis and by measuring the growth and uptake of nucleosides in the different mutants supplemented with different nucleosides. Two high affinity transporters were identified: BmpA-NupABC was shown to be an ABC transporter with the ability to actively transport all common nucleosides, whereas UriP was shown to be responsible for the uptake of only uridine and deoxyuridine. Interestingly, the four genes encoding the ABC transporter were found at different positions on the chromosome. The bmpA gene was separated from the nupABC operon by 60 kb. Moreover, bmpA was subject to regulation by purine availability, whereas the nupABC operon was constitutively expressed.
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Affiliation(s)
- Jan Martinussen
- Center for Systems Microbiology, DTU-Systems Biology, Building 301, Technical University of Denmark, DK-2800 Kgs Lyngby, Denmark
| | - Claus Sørensen
- Center for Systems Microbiology, DTU-Systems Biology, Building 301, Technical University of Denmark, DK-2800 Kgs Lyngby, Denmark
| | - Christian Bille Jendresen
- Center for Systems Microbiology, DTU-Systems Biology, Building 301, Technical University of Denmark, DK-2800 Kgs Lyngby, Denmark
| | - Mogens Kilstrup
- Center for Systems Microbiology, DTU-Systems Biology, Building 301, Technical University of Denmark, DK-2800 Kgs Lyngby, Denmark
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Anderson IJ, Dharmarajan L, Rodriguez J, Hooper S, Porat I, Ulrich LE, Elkins JG, Mavromatis K, Sun H, Land M, Lapidus A, Lucas S, Barry K, Huber H, Zhulin IB, Whitman WB, Mukhopadhyay B, Woese C, Bristow J, Kyrpides N. The complete genome sequence of Staphylothermus marinus reveals differences in sulfur metabolism among heterotrophic Crenarchaeota. BMC Genomics 2009; 10:145. [PMID: 19341479 PMCID: PMC2678158 DOI: 10.1186/1471-2164-10-145] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Accepted: 04/02/2009] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Staphylothermus marinus is an anaerobic, sulfur-reducing peptide fermenter of the archaeal phylum Crenarchaeota. It is the third heterotrophic, obligate sulfur reducing crenarchaeote to be sequenced and provides an opportunity for comparative analysis of the three genomes. RESULTS The 1.57 Mbp genome of the hyperthermophilic crenarchaeote Staphylothermus marinus has been completely sequenced. The main energy generating pathways likely involve 2-oxoacid:ferredoxin oxidoreductases and ADP-forming acetyl-CoA synthases. S. marinus possesses several enzymes not present in other crenarchaeotes including a sodium ion-translocating decarboxylase likely to be involved in amino acid degradation. S. marinus lacks sulfur-reducing enzymes present in the other two sulfur-reducing crenarchaeotes that have been sequenced -- Thermofilum pendens and Hyperthermus butylicus. Instead it has three operons similar to the mbh and mbx operons of Pyrococcus furiosus, which may play a role in sulfur reduction and/or hydrogen production. The two marine organisms, S. marinus and H. butylicus, possess more sodium-dependent transporters than T. pendens and use symporters for potassium uptake while T. pendens uses an ATP-dependent potassium transporter. T. pendens has adapted to a nutrient-rich environment while H. butylicus is adapted to a nutrient-poor environment, and S. marinus lies between these two extremes. CONCLUSION The three heterotrophic sulfur-reducing crenarchaeotes have adapted to their habitats, terrestrial vs. marine, via their transporter content, and they have also adapted to environments with differing levels of nutrients. Despite the fact that they all use sulfur as an electron acceptor, they are likely to have different pathways for sulfur reduction.
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Affiliation(s)
- Iain J Anderson
- Genome Biology Program, Joint Genome Institute, Walnut Creek, USA.
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Arimoto T, Igarashi T. Role of prolipoprotein diacylglyceryl transferase (Lgt) and lipoprotein-specific signal peptidase II (LspA) in localization and physiological function of lipoprotein MsmE inStreptococcus mutans. ACTA ACUST UNITED AC 2008; 23:515-9. [DOI: 10.1111/j.1399-302x.2008.00455.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Two closely related ABC transporters in Streptococcus mutans are involved in disaccharide and/or oligosaccharide uptake. J Bacteriol 2007; 190:168-78. [PMID: 17965163 DOI: 10.1128/jb.01509-07] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus mutans has a large number of transporters apparently involved in the uptake of carbohydrates. At least two of these, the multiple sugar metabolism transporter, MsmEFGK, and the previously uncharacterized MalXFGK, are members of the ATP-binding cassette (ABC) superfamily. Mutation analysis revealed that the MsmEFGK and MalXFGK transporters are principally involved in the uptake of distinct disaccharides and/or oligosaccharides. Furthermore, the data also indicated an unusual protein interaction between the components of these two related transporters. Strains lacking msmE (which encodes a solute binding protein) can no longer utilize raffinose or stachyose but grow normally on maltodextrins in the absence of MalT, a previously characterized EII(mal) phosphotransferase system component. In contrast, a mutant of malX (which encodes a solute binding protein) cannot utilize maltodextrins but grows normally on raffinose or stachyose. Radioactive uptake assays confirmed that MalX, but not MsmE, is required for uptake of [U-14C]maltotriose and that MalXFGK is principally involved in the uptake of maltodextrins with as many as 7 glucose units. Surprisingly, inactivation of the corresponding ATPase components did not result in an equivalent abolition of growth: the malK mutant can grow on maltotetraose as a sole carbon source, and the msmK mutant can utilize raffinose. We propose that the ATPase domains of these ABC transporters can interact with either their own or the alternative transporter complex. Such unexpected interaction of ATPase subunits with distinct membrane components to form complete multiple ABC transporters may be widespread in bacteria.
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Ajdić D, Pham VTT. Global transcriptional analysis of Streptococcus mutans sugar transporters using microarrays. J Bacteriol 2007; 189:5049-59. [PMID: 17496079 PMCID: PMC1951856 DOI: 10.1128/jb.00338-07] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transport of carbohydrates by Streptococcus mutans is accomplished by the phosphoenolpyruvate-phosphotransferase system (PTS) and ATP-binding cassette (ABC) transporters. To undertake a global transcriptional analysis of all S. mutans sugar transporters simultaneously, we used a whole-genome expression microarray. Global transcription profiles of S. mutans UA159 were determined for several monosaccharides (glucose, fructose, galactose, and mannose), disaccharides (sucrose, lactose, maltose, and trehalose), a beta-glucoside (cellobiose), oligosaccharides (raffinose, stachyose, and maltotriose), and a sugar alcohol (mannitol). The results revealed that PTSs were responsible for transport of monosaccharides, disaccharides, beta-glucosides, and sugar alcohol. Six PTSs were transcribed only if a specific sugar was present in the growth medium; thus, they were regulated at the transcriptional level. These included transporters for fructose, lactose, cellobiose, and trehalose and two transporters for mannitol. Three PTSs were repressed under all conditions tested. Interestingly, five PTSs were always highly expressed regardless of the sugar source used, presumably suggesting their availability for immediate uptake of most common dietary sugars (glucose, fructose, maltose, and sucrose). The ABC transporters were found to be specific for oligosaccharides, raffinose, stachyose, and isomaltosaccharides. Compared to the PTSs, the ABC transporters showed higher transcription under several tested conditions, suggesting that they might be transporting multiple substrates.
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Affiliation(s)
- Dragana Ajdić
- University of Oklahoma Health Sciences Center, Department of Microbiology and Immunology, 940 S. L. Young Blvd., Oklahoma City, OK 73104, USA.
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Webb AJ, Homer KA, Hosie AHF. A phosphoenolpyruvate-dependent phosphotransferase system is the principal maltose transporter in Streptococcus mutans. J Bacteriol 2007; 189:3322-7. [PMID: 17277067 PMCID: PMC1855833 DOI: 10.1128/jb.01633-06] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report that a phosphoenolpyruvate-dependent phosphotransferase system, MalT, is the principal maltose transporter for Streptococcus mutans. MalT also contributes to maltotriose uptake. Since maltose and maltodextrins are products of starch degradation found in saliva, the ability to take up and ferment these carbohydrates may contribute to dental caries.
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Affiliation(s)
- Alexander J Webb
- Microbiology, King's College London Dental Institute, Floor 28, Guy's Tower, King's College London, Guy's Campus, London SE1 9RT, United Kingdom
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