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Michel AM, Borrero-de Acuña JM, Molinari G, Ünal CM, Will S, Derksen E, Barthels S, Bartram W, Schrader M, Rohde M, Zhang H, Hoffmann T, Neumann-Schaal M, Bremer E, Jahn D. Cellular adaptation of Clostridioides difficile to high salinity encompasses a compatible solute-responsive change in cell morphology. Environ Microbiol 2022; 24:1499-1517. [PMID: 35106888 DOI: 10.1111/1462-2920.15925] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 11/27/2022]
Abstract
Infections by the pathogenic gut bacterium Clostridioides difficile cause severe diarrheas up to a toxic megacolon and are currently among the major causes of lethal bacterial infections. Successful bacterial propagation in the gut is strongly associated with the adaptation to changing nutrition-caused environmental conditions; e.g. environmental salt stresses. Concentrations of 350 mM NaCl, the prevailing salinity in the colon, led to significantly reduced growth of C. difficile. Metabolomics of salt- stressed bacteria revealed a major reduction of the central energy generation pathways, including the Stickland-fermentation reactions. No obvious synthesis of compatible solutes was observed up to 24 h of growth. The ensuing limited tolerance to high salinity and absence of compatible solute synthesis might result from an evolutionary adaptation to the exclusive life of C. difficile in the mammalian gut. Addition of the compatible solutes carnitine, glycine-betaine, γ-butyrobetaine, crotonobetaine, homobetaine, proline-betaine and dimethylsulfoniopropionate (DMSP) restored growth (choline and proline failed) under conditions of high salinity. A bioinformatically-identified OpuF-type ABC-transporter imported most of the used compatible solutes. A long-term adaptation after 48 h included a shift of the Stickland fermentation-based energy metabolism from the utilization to the accumulation of L-proline and resulted in restored growth. Surprisingly, salt stress resulted in the formation of coccoid C. difficile cells instead of the typical rod-shaped cells, a process reverted by the addition of several compatible solutes. Hence, compatible solute import via OpuF is the major immediate adaptation strategy of C. difficile to high salinity-incurred cellular stress. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Annika-Marisa Michel
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.,Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
| | - José Manuel Borrero-de Acuña
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.,Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany.,Universidad de Sevilla, Facultad de Biología, Departamento de Microbiología, Av. de la Reina Mercedes, n° 6, CP, 41012, Sevilla, Spain
| | - Gabriella Molinari
- Central Facility for Microscopy, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Can Murat Ünal
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Sabine Will
- Leibniz-Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Elisabeth Derksen
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Stefan Barthels
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.,Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
| | - Wiebke Bartram
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.,Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
| | - Michel Schrader
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Hao Zhang
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.,School of Life Science and Technology, Changchun University of Science and Technology, No. 7186 Weixing Road, 130022, Changchun, China
| | - Tamara Hoffmann
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany
| | - Meina Neumann-Schaal
- Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany.,Leibniz-Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany
| | - Dieter Jahn
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.,Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
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An antimicrobial Staphylococcus sciuri with broad temperature and salt spectrum isolated from the surface of the African social spider, Stegodyphus dumicola. Antonie Van Leeuwenhoek 2021; 114:325-335. [PMID: 33543432 DOI: 10.1007/s10482-021-01526-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 01/22/2021] [Indexed: 10/22/2022]
Abstract
Some social arthropods engage in mutualistic symbiosis with antimicrobial compound-producing microorganisms that provide protection against pathogens. Social spiders live in communal nests and contain specific endosymbionts with unknown function. Bacteria are also found on the spiders' surface, including prevalent staphylococci, which may have protective potential. Here we present the genomic and phenotypic characterization of strain i1, isolated from the surface of the social spider Stegodyphus dumicola. Phylogenomic analysis identified i1 as novel strain of Staphylococcus sciuri within subgroup 2 of three newly defined genomic subgroups. Further phenotypic investigations showed that S. sciuri i1 is an extremophile that can grow at a broad range of temperatures (4 °C-45 °C), high salt concentrations (up to 27%), and has antimicrobial activity against closely related species. We identified a lactococcin 972-like bacteriocin gene cluster, likely responsible for the antimicrobial activity, and found it conserved in two of the three subgroups of S. sciuri. These features indicate that S. sciuri i1, though not a specific symbiont, is well-adapted to survive on the surface of social spiders and may gain a competitive advantage by inhibiting closely related species.
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Lazrak A, Mandi L, Djeni TN, Neffa M, Ouazzani N. Assessing biomass diversity and performance of an activated sludge process treating saline table olive processing wastewater. ENVIRONMENTAL TECHNOLOGY 2019; 40:2608-2619. [PMID: 29493426 DOI: 10.1080/09593330.2018.1447603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 02/27/2018] [Indexed: 06/08/2023]
Abstract
This study aimed to determine the effects of salinity on the biomass behavior and its diversity in activated sludge process (ASP) treating the table olive processing wastewater (TOPW), and to evaluate ASP performances under increased TOPW concentration feeding, the numerical abundance, diversity and activity of the biomass, removal efficiencies of chemical oxygen demand (COD), phenolic compounds, nitrogen and phosphorus were evaluated. Results showed that biomass growth is very high and became faster according to an increase in the percentage of TOPW feeding and reached 5.2 gMLVSS l-1. The specific oxygen uptake rate (SOUR) analysis revealed that salinity up to 10 g l-1 provides an increase in biomass activity. SOUR reached a maximum of 20.3 gO2 gMLVSS-1 h-1. The increasing percentages of TOPW induce actually an evolution of microorganism's biodiversity; the microorganism communities were characterized by the abundance of halotolerant, Pseudomonas and Yeast genus that became the most abundant in the bioreactor as adaptation response against salinity. Furthermore, COD, phenolic compounds, nitrogen and phosphorus removal efficiencies attained 92.3%, 84.5%, 80% and 60%, respectively. A satisfactory release of extracellular polymeric substances is found to occur in the reactor with regard to increased saline TOPW, providing significant removal efficiencies and best settling of sludge.
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Affiliation(s)
- Asma Lazrak
- a Laboratory of Hydrobiology, Ecotoxicology and Sanitation (LHEA, URAC 33), BP/2390 , Marrakech , Morocco
- b National Center for Studies and Research on Water and Energy (CNEREE), BP/511, University Cadi Ayyad , Marrakech , Morocco
| | - Laila Mandi
- a Laboratory of Hydrobiology, Ecotoxicology and Sanitation (LHEA, URAC 33), BP/2390 , Marrakech , Morocco
- b National Center for Studies and Research on Water and Energy (CNEREE), BP/511, University Cadi Ayyad , Marrakech , Morocco
| | - Theodore N Djeni
- c Laboratory of Biotechnology and Food microbiology, University Nangui Abrogoua , Abidjan , Côte d'Ivoire
| | - Mounsef Neffa
- a Laboratory of Hydrobiology, Ecotoxicology and Sanitation (LHEA, URAC 33), BP/2390 , Marrakech , Morocco
- b National Center for Studies and Research on Water and Energy (CNEREE), BP/511, University Cadi Ayyad , Marrakech , Morocco
| | - Naaila Ouazzani
- a Laboratory of Hydrobiology, Ecotoxicology and Sanitation (LHEA, URAC 33), BP/2390 , Marrakech , Morocco
- b National Center for Studies and Research on Water and Energy (CNEREE), BP/511, University Cadi Ayyad , Marrakech , Morocco
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Ray SS, Misra S. A supervised weighted similarity measure for gene expressions using biological knowledge. Gene 2016; 595:150-160. [PMID: 27688070 DOI: 10.1016/j.gene.2016.09.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 08/18/2016] [Accepted: 09/22/2016] [Indexed: 11/17/2022]
Abstract
A supervised similarity measure for Saccharomyces cerevisiae gene expressions is developed which can capture the gene similarity when multiple types of experimental conditions like cell cycle, heat shock are available for all the genes. The measure is called Weighted Pearson correlation (WPC), where the weights are systematically determined for each type of experiment by maximizing the positive predictive value for gene pairs having Pearson correlation greater than 0.80. The positive predictive value is computed by using the annotation information available from yeast GO-Slim process annotations in Saccharomyces Genome Database (SGD). Genes are then clustered by k-medoid algorithm using the newly computed WPC, and functions of 135 unclassified genes are predicted with a p-value cutoff 10-5 using Munich Information for Protein Sequences (MIPS) annotations. Out of these genes, functional categories of 55 gene are predicted with p-value cutoff greater than 10-10 and reported in this investigation. The superiority of WPC as compared to some existing similarity measures like Pearson correlation and Euclidean distance is demonstrated using positive predictive (PPV) values of gene pairs for different Saccharomyces cerevisiae data sets. The related code is available at http://www.sampa.droppages.com/WPC.html.
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Affiliation(s)
- Shubhra Sankar Ray
- Machine Intelligence Unit, Indian Statistical Institute, Kolkata 700108, India; Center for Soft Computing Research, Indian Statistical Institute, Kolkata 700108, India.
| | - Sampa Misra
- Machine Intelligence Unit, Indian Statistical Institute, Kolkata 700108, India.
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6
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Abstract
Non-directed mutagenesis of the staphylococcal genome is a global approach that can be used to identify the genetic basis for phenotypes of interest as well as for identifying regulators of gene expression. One such approach that has been widely used in the study of S. aureus and S. epidermidis is transposon Tn917 mutagenesis to generate random libraries of mutants. This chapter describes the use of plasmid pLTV1 (containing Tn917-lac) to generate Tn917 transposon mutants. Through the use of temperature manipulation and antibiotic selection, staphylococcal strains harboring this plasmid can be effectively mutagenized to create random libraries amenable to subsequent phenotypic screening and identification of transposon insertion sites.
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Affiliation(s)
- Kelly C Rice
- Department of Microbiology and Cell Science, IFAS, University of Florida, Gainesville, FL, 32611-0700, USA.
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Cebrián G, Arroyo C, Condón S, Mañas P. Osmotolerance provided by the alternative sigma factors σB and rpoS to Staphylococcus aureus and Escherichia coli is solute dependent and does not result in an increased growth fitness in NaCl containing media. Int J Food Microbiol 2015; 214:83-90. [PMID: 26256716 DOI: 10.1016/j.ijfoodmicro.2015.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 06/24/2015] [Accepted: 07/03/2015] [Indexed: 12/22/2022]
Abstract
The aim of this work was to examine the role of the alternative general stress sigma factors σ(B) and rpoS on the ability of Staphylococcus aureus and Escherichia coli, respectively, to grow in liquid and solid media of different osmolarity. For this purpose, S. aureus strain Newman and its isogenic ΔsigB mutant IK84 and E. coli strain BJ4 and its isogenic ΔrpoS mutant BJ4L1 were grown in media (TSBYE) with different concentrations of NaCl. Growth parameters (lag phase duration, growth rate and maximum number of microorganisms) and limiting growth concentrations (Maximum Non-Inhibitory Concentration - MNIC - and Minimum Inhibitory Concentration - MIC-) were determined. The mechanisms underlying the differences observed between parental and mutant strains were also explored. The absence of the sigma factors σ(B) and rpoS led to a decrease in the MNICs and MICs calculated for S. aureus and E. coli, respectively. Conversely, neither σ(B) nor rpoS provided with increased growth fitness to S. aureus and E. coli cells at NaCl concentrations up to 1.36M and 1M, respectively. The decreased osmotolerance of the σ(B) and rpoS deficient strains, as compared to their parental strains, was compensated by the addition of glycine-betaine (1mM) to the growth medium. It was also observed that the decreased tolerance to NaCl of the mutant strains was coincident with a decreased tolerance to sucrose, KCl, and LiCl but not to glycerol, MgCl2, and CaCl2. Results obtained also demonstrate that the increased osmotolerance of stationary growth phase E. coli cells, as compared to exponential growth phase ones, would be due to the activation of both rpoS-independent and rpoS-dependent mechanisms. This work will help to understand the mechanisms of bacterial resistance to osmotic stress and the role of the alternative sigma factors σ(B) and rpoS in this process.
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Affiliation(s)
- G Cebrián
- Tecnología de los Alimentos, Facultad de Veterinaria de Zaragoza, Universidad de Zaragoza, C/ Miguel Servet, 177, 50013 Zaragoza, Spain.
| | - C Arroyo
- Tecnología de los Alimentos, Facultad de Veterinaria de Zaragoza, Universidad de Zaragoza, C/ Miguel Servet, 177, 50013 Zaragoza, Spain
| | - S Condón
- Tecnología de los Alimentos, Facultad de Veterinaria de Zaragoza, Universidad de Zaragoza, C/ Miguel Servet, 177, 50013 Zaragoza, Spain
| | - P Mañas
- Tecnología de los Alimentos, Facultad de Veterinaria de Zaragoza, Universidad de Zaragoza, C/ Miguel Servet, 177, 50013 Zaragoza, Spain
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Role of BrnQ1 and BrnQ2 in branched-chain amino acid transport and virulence in Staphylococcus aureus. Infect Immun 2014; 83:1019-29. [PMID: 25547798 DOI: 10.1128/iai.02542-14] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The branched-chain amino acids (BCAAs; Ile, Leu, and Val) not only are important nutrients for the growth of Staphylococcus aureus but also are corepressors for CodY, which regulates virulence gene expression, implicating BCAAs as an important link between the metabolic state of the cell and virulence. BCAAs are either synthesized intracellularly or acquired from the environment. S. aureus encodes three putative BCAA transporters, designated BrnQ1, BrnQ2, and BrnQ3; their functions have not yet been formally tested. In this study, we mutated all three brnQ paralogs so as to characterize their substrate specificities and their roles in growth in vitro and in vivo. We demonstrated that in the community-associated, methicillin-resistant S. aureus (CA-MRSA) strain USA300, BrnQ1 is involved in uptake of all three BCAAs, BrnQ2 transports Ile, and BrnQ3 does not have a significant role in BCAA transport under the conditions tested. Of the three, only BrnQ1 is essential for USA300 to grow in a chemically defined medium that is limited for Leu or Val. Interestingly, we observed that a brnQ2 mutant grew better than USA300 in media limited for Leu and Val, owing to the fact that this mutation leads to overexpression of brnQ1. In a murine infection model, the brnQ1 mutant was attenuated, but in contrast, brnQ2 mutants had significantly increased virulence compared to that of USA300, a phenotype we suggest is at least partially linked to enhanced in vivo scavenging of Leu and Val through BrnQ1. These data uncover a hitherto-undiscovered connection between nutrient acquisition and virulence in CA-MRSA.
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Price-Whelan A, Poon CK, Benson MA, Eidem TT, Roux CM, Boyd JM, Dunman PM, Torres VJ, Krulwich TA. Transcriptional profiling of Staphylococcus aureus during growth in 2 M NaCl leads to clarification of physiological roles for Kdp and Ktr K+ uptake systems. mBio 2013; 4:e00407-13. [PMID: 23963175 PMCID: PMC3747578 DOI: 10.1128/mbio.00407-13] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/24/2013] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Staphylococcus aureus exhibits an unusually high level of osmotolerance and Na(+) tolerance, properties that support survival in various host niches and in preserved foods. The genetic basis of these traits is not well understood. We compared the transcriptional profiles of S. aureus grown in complex medium with and without 2 M NaCl. The stimulon for growth in high-osmolality media and Na(+) included genes involved in uptake of K(+), other compatible solutes, sialic acid, and sugars; capsule biosynthesis; and amino acid and central metabolism. Quantitative PCR analysis revealed that the loci responded differently from each other to high osmolality imposed by elevated NaCl versus sucrose. High-affinity K(+) uptake (kdp) genes and capsule biosynthesis (cap5) genes required the two-component system KdpDE for full induction by osmotic stress, with kdpA induced more by NaCl and cap5B induced more by sucrose. Focusing on K(+) importers, we identified three S. aureus genes belonging to the lower-affinity Trk/Ktr family that encode two membrane proteins (KtrB and KtrD) and one accessory protein (KtrC). In the absence of osmotic stress, the ktr gene transcripts were much more abundant than the kdpA transcript. Disruption of S. aureus kdpA caused a growth defect under low-K(+) conditions, disruption of ktrC resulted in a significant defect in 2 M NaCl, and a ΔktrC ΔkdpA double mutant exhibited both phenotypes. Protective effects of S. aureus Ktr transporters at elevated NaCl are consistent with previous indications that both Na(+) and osmolality challenges are mitigated by the maintenance of a high cytoplasmic K(+) concentration. IMPORTANCE There is general agreement that the osmotolerance and Na(+) tolerance of Staphylococcus aureus are unusually high for a nonhalophile and support its capacity for human colonization, pathogenesis, and growth in food. Nonetheless, the molecular basis for these properties is not well defined. The genome-wide response of S. aureus to a high concentration, 2 M, of NaCl revealed the upregulation of expected genes, such as those for transporters of compatible solutes that are widely implicated in supporting osmotolerance. A high-affinity potassium uptake system, KdpFABC, was upregulated, although it generally plays a physiological role under very low K(+) conditions. At higher K(+) concentrations, a lower-affinity and more highly expressed type of K(+) transporter system, Ktr transporters, was shown to play a significant role in high Na(+) tolerance. This study illustrates the importance of the K(+) status of the cell for tolerance of Na(+) by S. aureus and underscores the importance of monovalent cation cycles in this pathogen.
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Affiliation(s)
- Alexa Price-Whelan
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Chun Kit Poon
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Meredith A. Benson
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Tess T. Eidem
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA
| | - Christelle M. Roux
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA
| | - Jeffrey M. Boyd
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Terry A. Krulwich
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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The essential yhcSR two-component signal transduction system directly regulates the lac and opuCABCD operons of Staphylococcus aureus. PLoS One 2012; 7:e50608. [PMID: 23226327 PMCID: PMC3511567 DOI: 10.1371/journal.pone.0050608] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 10/26/2012] [Indexed: 01/27/2023] Open
Abstract
Our previous studies suggested that the essential two-component signal transduction system, YhcSR, regulates the opuCABCD operon at the transcriptional level, and the Pspac-driven opuCABCD partially complements the lethal effects of yhcS antisense RNA expression in Staphylococcus aureus. However, the reason why yhcSR regulon is required for growth is still unclear. In this report, we present that the lac and opuC operons are directly transcriptionally regulated by YhcSR. Using real-time RT-PCR we showed that the down-regulation of yhcSR expression affected the transcription of lacA encoding galactose-6-phosphotase isomerase subunit LacA, and opuCA encoding a subunit of a glycine betaine/carnitine/choline ABC transporter. Promoter-lux reporter fusion studies further confirmed the transcriptional regulation of lac by YhcSR. Gel shift assays revealed that YhcR binds to the promoter regions of the lac and opuC operons. Moreover, the Pspac-driven lacABC expression in trans was able to partially complement the lethal effect of induced yhcS antisense RNA. Likewise, the Pspac-driven opuCABCD expression in trans complemented the growth defect of S. aureus in a high osmotic strength medium during the depletion of YhcSR. Taken together, the above data indicate that the yhcSR system directly regulates the expression of lac and opuC operons, which, in turn, may be partially associated with the essentiality of yhcSR in S. aureus. These results provide a new insight into the biological functions of the yhcSR, a global regulator.
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Wetzel KJ, Bjorge D, Schwan WR. Mutational and transcriptional analyses of the Staphylococcus aureus low-affinity proline transporter OpuD during in vitro growth and infection of murine tissues. ACTA ACUST UNITED AC 2011; 61:346-55. [PMID: 21231964 DOI: 10.1111/j.1574-695x.2011.00781.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Staphylococcus aureus continues to be a major health problem. This species' requirement for proline and proline transport from the extracellular environment is not well understood. Here, we identify a S. aureus low-affinity proline transport gene (opuD) with homology to the OpuD protein of Bacillus subtilis. Mutation of the opuD gene caused a significant decline in proline uptake under low-affinity conditions as compared with wild type, but the opuD mutant strain showed no significant attenuation in a murine abscess model of infection. The S. aureus opuD gene was transcriptionally activated during growth in moderate osmolarity media with high levels of proline or glycine betaine independent of SigB. In murine abscesses, the opuD gene was activated at a later time point, whereas the opuD expression dropped over the course of an 18-h period within murine urinary tracts. Transcriptional regulation of opuD in S. aureus appears to be coordinated within this species when grown in moderate to high NaCl environments, but the level of extracellular proline had a marked effect on expression of this proline transport gene. The differential regulation of proline transport genes in S. aureus may be an adaptation for life in a variety of environments, including survival within the human body.
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Affiliation(s)
- Keith J Wetzel
- Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI, USA
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12
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Chaibenjawong P, Foster SJ. Desiccation tolerance in Staphylococcus aureus. Arch Microbiol 2010; 193:125-35. [PMID: 21088825 DOI: 10.1007/s00203-010-0653-x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 10/22/2010] [Accepted: 11/05/2010] [Indexed: 12/20/2022]
Abstract
Staphylococcus aureus is a multidrug-resistant pathogen that not only causes a diverse array of human diseases, but also is able to survive in potentially dry and stressful environments, such as the human nose, on skin and on inanimate surfaces such as clothing and surfaces. This study investigated parameters governing desiccation tolerance of S. aureus and identified several components involved in the process. Initially, the role of environmental parameters such as temperature, growth phase, cell density, desiccation time and protectants in desiccation tolerance were determined. This established a robust model of desiccation tolerance in which S. aureus has the ability to survive on dry plastic surfaces for more than 1,097 days. Using a combination of a random screen and defined mutants, clpX, sigB and yjbH were identified as being required for desiccation tolerance. ClpX is a part of the ATP-dependent ClpXP protease, important for protein turnover, and YjbH has a proposed linked function. SigB is an accessory sigma factor with a role in generalized stress resistance. Understanding the molecular mechanisms that govern desiccation tolerance may determine the break points to be exploited to prevent the spread of this dangerous pathogen in hospitals and communities.
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Affiliation(s)
- Plykaeow Chaibenjawong
- Department of Molecular Biology and Biotechnology, Krebs Institute, University of Sheffield, Sheffield S10 2TN, UK
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Co-ordinate expression of glycine betaine synthesis genes linked by the FMDV 2A region in a single open reading frame in Pichia pastoris. Appl Microbiol Biotechnol 2007; 77:891-9. [DOI: 10.1007/s00253-007-1222-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 09/19/2007] [Accepted: 09/21/2007] [Indexed: 11/30/2022]
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14
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Nagarajan T, Vanderleyden J, Tripathi AK. Identification of salt stress inducible genes that control cell envelope related functions in Azospirillum brasilense Sp7. Mol Genet Genomics 2007; 278:43-51. [PMID: 17340145 DOI: 10.1007/s00438-007-0224-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2007] [Accepted: 02/14/2007] [Indexed: 11/26/2022]
Abstract
Plant growth promoting rhizobacteria such as Azospirillum brasilense are agronomically important as they are frequently used for crop inoculation. But adverse factors such as increasing soil salinity limit their survival, multiplication and phytostimulatory effect. In order to understand the role of the genes involved in the adaptation of A. brasilense Sp7 to salt stress, a mutant library (6,800 mutants) was constructed after random integration of a mini-Transposon Tn5 derivative containing a promoterless gusA and oriV. The library was screened for salt stress inducible Gus activity on minimal malate agar medium containing NaCl and 5-bromo-4-chloro-3-indolyl-beta-D: -glucuronide. Salt stress responsiveness of the promoters was estimated by quantifying GusA activity in the presence and absence of NaCl stress using p-nitrophenyl-beta-D: -glucuronide as a substrate. In 11 mutants showing high levels of gusA expression in the presence of salt-stress, the partial nucleotide sequence of the DNA region flanking the site of Tn5 insertion was determined and analysed using the NCBI-BLAST programs. Similarity searches revealed that 10 out of the 11 genes sequenced showed notable similarity with genes involved in functions related to modulation in the composition of exopolysaccharides, capsular polysaccharides, lipopolysaccharides, peptidoglycan and lipid bilayer of the cell envelope. Induction of cell envelope related genes in response to salt stress and salt sensitive phenotype of several mutants in A. brasilense indicate a prominent role of cell envelope in salt-stress adaptation.
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Affiliation(s)
- Thirunavukkarasu Nagarajan
- Bacterial Genetics Laboratory, School of Biotechnology, Faculty of Science, Banaras Hindu University, Varanasi, 221005, India
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15
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Swartz TH, Ito M, Ohira T, Natsui S, Hicks DB, Krulwich TA. Catalytic properties of Staphylococcus aureus and Bacillus members of the secondary cation/proton antiporter-3 (Mrp) family are revealed by an optimized assay in an Escherichia coli host. J Bacteriol 2007; 189:3081-90. [PMID: 17293423 PMCID: PMC1855852 DOI: 10.1128/jb.00021-07] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Monovalent cation proton antiporter-3 (Mrp) family antiporters are widely distributed and physiologically important in prokaryotes. Unlike other antiporters, they require six or seven hydrophobic gene products for full activity. Standard fluorescence-based assays of Mrp antiport in membrane vesicles from Escherichia coli transformants have not yielded strong enough signals for characterization of antiport kinetics. Here, an optimized assay protocol for vesicles of antiporter-deficient E. coli EP432 transformants produced higher levels of secondary Na(+)(Li(+))/H(+) antiport than previously reported. Assays were conducted on Mrps from alkaliphilic Bacillus pseudofirmus OF4 and Bacillus subtilis and the homologous antiporter of Staphylococcus aureus (Mnh), all of which exhibited Na(+)(Li(+))/H(+) antiport. A second paralogue of S. aureus (Mnh2) did not. K(+), Ca(2+), and Mg(2+) did not support significant antiport by any of the test antiporters. All three Na(+)(Li(+))/H(+) Mrp antiporters had alkaline pH optima and apparent K(m) values for Na(+) that are among the lowest reported for bacterial Na(+)/H(+) antiporters. Using a fluorescent probe of the transmembrane electrical potential (DeltaPsi), Mrp Na(+)/H(+) antiport was shown to be DeltaPsi consuming, from which it is inferred to be electrogenic. These assays also showed that membranes from E. coli EP432 expressing Mrp antiporters generated higher DeltaPsi levels than control membranes, as did membranes from E. coli EP432 expressing plasmid-borne NhaA, the well-characterized electrogenic E. coli antiporter. Assays of respiratory chain components in membranes from Mrp and control E. coli transformants led to a hypothesis explaining how activity of secondary, DeltaPsi-consuming antiporters can elicit increased capacity for DeltaPsi generation in a bacterial host.
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Affiliation(s)
- Talia H Swartz
- Department of Pharmacology and Biological Chemistry, Box 1603, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, NY 10029, USA
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16
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Ohnishi N, Murata N. Glycinebetaine counteracts the inhibitory effects of salt stress on the degradation and synthesis of D1 protein during photoinhibition in Synechococcus sp. PCC 7942. PLANT PHYSIOLOGY 2006; 141:758-65. [PMID: 16632587 PMCID: PMC1475447 DOI: 10.1104/pp.106.076976] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Glycinebetaine (hereafter referred to as betaine) is a compatible solute that accumulates in certain plants and microorganisms in response to various types of stress. We demonstrated previously that when the cyanobacterium Synechococcus sp. PCC 7942 (hereafter Synechococcus) is transformed with the codA gene for choline oxidase, it can synthesize betaine from exogenously supplied choline, exhibiting enhanced tolerance to salt and cold stress. In this study, we examined the effects of salt stress and betaine synthesis on the photoinhibition of photosystem II (PSII). Salt stress due to 220 mm NaCl enhanced photoinhibition of PSII and betaine protected PSII against photoinhibition under these conditions. However, neither salt stress nor betaine synthesis affected photodamage to PSII. By contrast, salt stress inhibited repair of photodamaged PSII and betaine reversed this inhibitory effect of salt stress. Pulse-chase-labeling experiments revealed that salt stress inhibited degradation of D1 protein in photodamaged PSII and de novo synthesis of D1. By contrast, betaine protected the machinery required for degradation and synthesis of D1 under salt stress. Neither salt stress nor betaine affected levels of psbA transcripts. These observations suggest that betaine counteracts the inhibitory effects of salt stress, with resultant accelerated repair of photodamaged PSII.
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Affiliation(s)
- Norikazu Ohnishi
- National Institute for Basic Biology, Myodaiji, Okazaki 444-8585, Japan
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17
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Stewart CM, Cole MB, Legan JD, Slade L, Schaffner DW. Solute-specific effects of osmotic stress on Staphylococcus aureus. J Appl Microbiol 2005; 98:193-202. [PMID: 15610432 DOI: 10.1111/j.1365-2672.2004.02445.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM To determine if cell death from osmotic stress is because of lack of sufficient energy to maintain cell metabolism. Additionally, the solute-specific effect of five humectants on bacterial osmoregulation and cell survival was examined. METHODS AND RESULTS Staphylococcus aureus was placed into 84% relative humidity (RH) broth (five humectants used individually). ATP, ADP and cell viability measurements were determined over time. The results indicate that ATP is not the limiting factor for cell survival under excessive osmotic stress. Although the same RH was achieved with various humectants, the rates of cell death varied greatly as did the sensitivities of the cell populations to osmotic stress. CONCLUSIONS The results from this study provide strong evidence that mechanisms of osmotic inactivation depend on the solute. The molecular mobility of the system may be an important means to explain these differences. SIGNIFICANCE AND IMPACT OF THE STUDY By bringing together an understanding of solute-specific effects, microbial physiology and genetics, the mechanisms of inactivation of micro-organisms by solute-specific osmotic stress may be elucidated, and this knowledge may then be exploited to ensure the production of high quality, safe foods.
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18
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Swartz TH, Ikewada S, Ishikawa O, Ito M, Krulwich TA. The Mrp system: a giant among monovalent cation/proton antiporters? Extremophiles 2005; 9:345-54. [PMID: 15980940 DOI: 10.1007/s00792-005-0451-6] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Accepted: 04/08/2005] [Indexed: 10/25/2022]
Abstract
Mrp systems are a novel and broadly distributed type of monovalent cation/proton antiporter of bacteria and archaea. Monovalent cation/proton antiporters are membrane transport proteins that catalyze efflux of cytoplasmic sodium, potassium or lithium ions in exchange for external hydrogen ions (protons). Other known monovalent cation antiporters are single gene products, whereas Mrp systems have been proposed to function as hetero-oligomers. A mrp operon typically has six or seven genes encoding hydrophobic proteins all of which are required for optimal Mrp-dependent sodium-resistance. There is little sequence similarity of Mrp proteins to other antiporters but three of these proteins have significant sequence similarity to membrane embedded subunits of ion-translocating electron transport complexes. Mrp antiporters have essential roles in the physiology of alkaliphilic and neutralophilic Bacillus species, nitrogen-fixing Sinorhizobium meliloti and in the pathogen Staphylococcus aureus, although these bacteria contain multiple monovalent cation/proton antiporters. The wide distribution of Mrp systems leads to the anticipation of important roles in an even wider variety of pathogens, extremophiles and environmentally important organisms. Here, the distribution, established physiological roles and catalytic activities of Mrp systems are reviewed, hypotheses regarding their complexity are discussed and major open questions about their function are highlighted.
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Affiliation(s)
- Talia H Swartz
- Department of Pharmacology & Biological Chemistry, Mount Sinai School of Medicine, New York, NY 10029, USA
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19
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Frees D, Chastanet A, Qazi S, Sørensen K, Hill P, Msadek T, Ingmer H. Clp ATPases are required for stress tolerance, intracellular replication and biofilm formation in Staphylococcus aureus. Mol Microbiol 2005; 54:1445-62. [PMID: 15554981 DOI: 10.1111/j.1365-2958.2004.04368.x] [Citation(s) in RCA: 236] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Hsp100/Clp ATPases constitute a family of closely related proteins of which some members function solely as chaperones whereas others additionally can associate with the unrelated ClpP peptidase forming a Clp proteolytic complex. We have investigated the role of four Clp ATPases in the versatile pathogen, Staphylococcus aureus. Previously, we showed that ClpX is required for expression of major virulence factors and for virulence of S. aureus, but not for survival during heat shock. In the present study, we have inactivated clpC, clpB and clpL and, while none of these mutations affected toxin production, both ClpC and ClpB and to a minor extent ClpL were required for intracellular multiplication within bovine mammary epithelial cells. These defects were paralleled by an inability of the clpC mutant to grow at high temperature and of the clpB mutant to induce thermotolerance indicating that the protective functions of these proteins are required both at high temperature and during infection. By primer extension analysis and footprint studies, we show that expression of clpC and clpB is controlled by the negative heat-shock regulator, CtsR, and that ClpC is required for its repressor activity. Thus, ClpC is a likely sensor of stress encountered during both environmental stress and infection. In addition to virulence factor production the ability to form biofilms is of importance to S. aureus as a nosocomial pathogen. Interestingly, biofilm formation was reduced in the absence of ClpX or ClpC whereas it was enhanced in the absence of ClpP. Thus, our data show that Clp proteolytic complexes and the Clp ATPases control several key processes of importance to the success of S. aureus as a pathogen.
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Affiliation(s)
- Dorte Frees
- Department of Veterinary Pathobiology, Royal Veterinary and Agricultural University (KVL), Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark
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20
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Brown JS, Gilliland SM, Basavanna S, Holden DW. phgABC, a three-gene operon required for growth of Streptococcus pneumoniae in hyperosmotic medium and in vivo. Infect Immun 2004; 72:4579-88. [PMID: 15271918 PMCID: PMC470583 DOI: 10.1128/iai.72.8.4579-4588.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
To cause disease, bacterial pathogens need to be able to adapt to the physiological conditions found within the host, including an osmolality of approximately 290 mosmol kg(-1). While investigating Streptococcus pneumoniae genes contained within pneumococcal pathogenicity island 1, we identified a three-gene operon of unknown function termed phgABC. PhgC has a domain with similarity to diacylglycerol kinases of eukaryotes and is the first described member of a family of related proteins found in many gram-positive bacteria. phgA and phgC mutant strains were constructed by insertional duplication mutagenesis and found to have impaired growth under conditions of high osmotic and oxidative stress. The compatible solutes proline and glycine betaine improved growth of the wild-type and the phgA mutant strains in hyperosmolar medium, and when analyzed by electron microscopy, the cellular morphology of the phgA mutant strain was unaffected by osmotic stress. The phgA and phgC mutant strains were reduced in virulence in models of both systemic and pulmonary infection. As the virulence of the phgA mutant strain was not restored in gp91phox(-/-) mice and the phgA and phgC mutant strains had reduced growth in both blood and serum, the reduced virulence of these strains is unlikely to be due to increased sensitivity to the respiratory burst of phagocytes but is, instead, due to impaired growth at physiological osmolality.
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Affiliation(s)
- Jeremy S Brown
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, 5 University Street, London WC1E 6JJ, United Kingdom.
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21
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Scybert S, Pechous R, Sitthisak S, Nadakavukaren MJ, Wilkinson BJ, Jayaswal RK. NaCl-sensitive mutant of Staphylococcus aureus has a Tn917-lacZ insertion in its ars operon. FEMS Microbiol Lett 2003; 222:171-6. [PMID: 12770703 DOI: 10.1016/s0378-1097(03)00312-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Staphylococcus aureus is a Gram-positive bacterium that is extremely halotolerant. To investigate the molecular mechanisms by which S. aureus can cope with osmotic stress, Tn917-lacZ-induced NaCl-sensitive mutants were isolated. An NaCl-sensitive mutant showed a longer lag period, slower growth rate, and lower final culture turbidity than the parent strain in liquid medium containing 1.5 M NaCl. Electron microscopic observation of the NaCl-sensitive mutant under NaCl stress conditions revealed large, pseudo-multicellular cells. Addition of exogenous osmoprotectants, such as glycine betaine, choline, L-proline, and proline betaine, did not relieve the NaCl sensitivity of the mutant. The region flanking the transposon insertion site in the NaCl-sensitive S. aureus chromosome was sequenced. The mutated gene was 99% identical to arsR, the arsenic operon regulatory protein present on the pI258 plasmid of S. aureus. The ars operon from pI258 was subcloned into the shuttle vector pLI50 and transferred into the NaCl-sensitive mutant. The ars operon in trans restored NaCl tolerance in the mutant, suggesting that NaCl sensitivity is due to the mutation in arsR.
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Affiliation(s)
- Sarah Scybert
- Microbiology Group, Department of Biological Sciences, Illinois State University, Normal, IL 61790-4120, USA
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22
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Ferjani A, Mustardy L, Sulpice R, Marin K, Suzuki I, Hagemann M, Murata N. Glucosylglycerol, a compatible solute, sustains cell division under salt stress. PLANT PHYSIOLOGY 2003; 131:1628-37. [PMID: 12692322 PMCID: PMC166919 DOI: 10.1104/pp.102.017277] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2002] [Revised: 12/10/2002] [Accepted: 12/20/2002] [Indexed: 05/20/2023]
Abstract
The cyanobacterium Synechocystis sp. PCC 6803 accumulates the compatible solute glucosylglycerol (GG) and sucrose under salt stress. Although the molecular mechanisms for GG synthesis including regulation of the GG-phosphate synthase (ggpS) gene, which encodes GgpS, has been intensively investigated, the role of GG in protection against salt stress remains poorly understood. In our study of the role of GG in the tolerance to salt stress, we found that salt stress due to 450 mM NaCl inhibited cell division and significantly increased cell size in DeltaggpS mutant cells, whereas the inhibition of cell division and increase in cell size were observed in wild-type cells at high concentrations of NaCl, such as 800 mM. Electron microscopy revealed that, in DeltaggpS cells, separation of daughter cells was incomplete, and aborted division could be recognized by the presence of a structure that resembled a division ring. The addition of GG to the culture medium protected DeltaggpS cells against salt stress and reversed the adverse effects of NaCl on cell division and cell size. These observations suggest that GG is important for salt tolerance and thus for the proper division of cells under salt stress conditions.
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Affiliation(s)
- Ali Ferjani
- Department of Regulation Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
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23
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Vilhelmsson O, Miller KJ. Synthesis of pyruvate dehydrogenase in Staphylococcus aureus is stimulated by osmotic stress. Appl Environ Microbiol 2002; 68:2353-8. [PMID: 11976108 PMCID: PMC127531 DOI: 10.1128/aem.68.5.2353-2358.2002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2001] [Accepted: 02/14/2002] [Indexed: 11/20/2022] Open
Abstract
The pyruvate dehydrogenase multienzyme complex (PDHC) was found to be upregulated by osmotic stress in the osmotolerant pathogen Staphylococcus aureus. Upregulation was detectable in the levels of both activity and protein and was judged to be about fourfold when sodium chloride was used to adjust the water activity (a(w)) of the growth medium to 0.94. The upregulation of the PDHC was also found to be humectant dependent and was greatest when impermeant, nonmetabolizable humectants were used to adjust a(w). Further experiments provided evidence that in addition to osmotic upregulation, the PDHC complex is also subject to catabolite repression, thus providing a possible explanation for the observation that high concentrations of carbohydrates are generally more inhibitory to the growth of this bacterial pathogen than are high concentrations of salts.
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Affiliation(s)
- Oddur Vilhelmsson
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
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24
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Singh VK, Jayaswal RK, Wilkinson BJ. Cell wall-active antibiotic induced proteins of Staphylococcus aureus identified using a proteomic approach. FEMS Microbiol Lett 2001; 199:79-84. [PMID: 11356571 DOI: 10.1111/j.1574-6968.2001.tb10654.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Proteins produced in elevated amounts in response to oxacillin challenge of Staphylococcus aureus strain RN450, were studied by comparing Coomassie blue stained two-dimensional gels of cellular proteins. At least nine proteins were produced in elevated amounts following exposure to growth inhibitory concentrations of oxacillin. N-terminal sequences were obtained for five of the proteins and the databases were searched to tentatively identify them. The proteins were identified as homologs of (i) methionine sulfoxide reductase (MsrA); (ii) a signal transduction protein (TRAP) involved in regulating RNAIII production encoded by the agr locus; (iii) transcription elongation factor GreA; (iv) the heat shock protein GroES; and (v) the enzyme IIA component of the phosphoenolpyruvate:sugar phosphotransferase system. A similar induction response was observed with the other cell wall-active antibiotics, but not with antibiotics that affect other cellular targets. Increased transcription of the msrA and groEL genes in response to cell wall-active antibiotics was also demonstrated. Although net protein synthesis is inhibited subsequent to inhibition of peptidoglycan biosynthesis by cell wall-active antibiotics, some proteins are induced in S. aureus, presumably in an attempt by the cell to counter the inhibitory effects of these agents.
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Affiliation(s)
- V K Singh
- Microbiology Group, Department of Biological Sciences, Illinois State University, Normal, IL 61790-4120, USA
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25
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Cabrera G, Xiong A, Uebel M, Singh VK, Jayaswal RK. Molecular characterization of the iron-hydroxamate uptake system in Staphylococcus aureus. Appl Environ Microbiol 2001; 67:1001-3. [PMID: 11157278 PMCID: PMC92682 DOI: 10.1128/aem.67.2.1001-1003.2001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To investigate iron uptake, a chromosomal locus containing three consecutive open reading frames, designated fhuC, fhuB, and fhuD, was identified in Staphylococcus aureus. Whereas the fhuC gene encodes an ATP-binding protein, fhuB and fhuD code for ferrichrome permeases and thus resemble an ATP-binding cassette transporter. A fhuB knockout mutant showed impaired uptake of iron bound to the siderophores but not of ferric chloride, suggesting that this operon is specific for siderophore-mediated iron uptake.
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Affiliation(s)
- G Cabrera
- Microbiology Group, Department of Biological Sciences, Illinois State University, Normal, Illinois 61790-4120, USA
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26
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Shebuski JR, Vilhelmsson O, Miller KJ. Effects of growth at low water activity on the thermal tolerance of Staphylococcus aureus. J Food Prot 2000; 63:1277-81. [PMID: 10983806 DOI: 10.4315/0362-028x-63.9.1277] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Staphylococcus aureus is the most osmotolerant foodborne pathogen, and outbreaks of staphylococcal food poisoning are often linked to foods of reduced water activity (a(w)) values. While it is generally known that the thermal tolerance of microorganisms increases as the a(w) of the heating menstruum is decreased, surprisingly little research has examined the influence of growth medium a(w) on microbial thermal tolerance. In the present study, we show that growth of S. aureus at an a(w) value of 0.94 leads to the development of dramatically enhanced thermal tolerance (i.e., less than 1 log reduction after heating for 20 min at 60 degrees C). We further show that the identity of the accumulated compatible solute within cells grown at low a(w) can also influence the overall level of thermal tolerance of S. aureus. Finally, we provide evidence that the synthesis of general stress and/or osmotic stress proteins is required for the development of enhanced thermal tolerance of S. aureus at low a(w).
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Affiliation(s)
- J R Shebuski
- Department of Food Science, The Pennsylvania State University, University Park 16802, USA
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27
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Chalker AF, Ingraham KA, Lunsford RD, Bryant AP, Bryant J, Wallis NG, Broskey JP, Pearson SC, Holmes DJ. The bacA gene, which determines bacitracin susceptibility in Streptococcus pneumoniae and Staphylococcus aureus, is also required for virulence. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 7):1547-1553. [PMID: 10878119 DOI: 10.1099/00221287-146-7-1547] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Homologues of Escherichia coli bacA, encoding extremely hydrophobic proteins, were identified in the genomes of Staphylococcus aureus and Streptococcus pneumoniae. Allelic replacement mutagenesis demonstrated that the gene is not essential for in vitro growth in either organism, and the mutants showed no significant changes in growth rate or morphology. The Staph. aureus bacA mutant showed slightly reduced virulence in a mouse model of infection and an eightfold increase in bacitracin susceptibility. However, a Strep. pneumoniae bacA mutant was highly attenuated in a mouse model of infection, and demonstrated an increase in susceptibility to bacitracin of up to 160000-fold. These observations are consistent with the previously proposed role of BacA protein as undecaprenol kinase.
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Affiliation(s)
- Alison F Chalker
- Anti-Infective Research (UP1345), SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, PO Box 5089, Collegeville, PA19426-0989, USA1
| | - Karen A Ingraham
- Anti-Infective Research (UP1345), SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, PO Box 5089, Collegeville, PA19426-0989, USA1
| | - R Dwayne Lunsford
- Anti-Infective Research (UP1345), SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, PO Box 5089, Collegeville, PA19426-0989, USA1
| | - Alexander P Bryant
- Anti-Infective Research (UP1345), SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, PO Box 5089, Collegeville, PA19426-0989, USA1
| | - Joanna Bryant
- Anti-Infective Research (UP1345), SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, PO Box 5089, Collegeville, PA19426-0989, USA1
| | - Nicola G Wallis
- Anti-Infective Research (UP1345), SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, PO Box 5089, Collegeville, PA19426-0989, USA1
| | - John P Broskey
- Anti-Infective Research (UP1345), SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, PO Box 5089, Collegeville, PA19426-0989, USA1
| | - Stewart C Pearson
- Anti-Infective Research (UP1345), SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, PO Box 5089, Collegeville, PA19426-0989, USA1
| | - David J Holmes
- Anti-Infective Research (UP1345), SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, PO Box 5089, Collegeville, PA19426-0989, USA1
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28
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Abstract
Listeria monocytogenes is a foodborne pathogen that can grow in high osmotic strength environments and at refrigeration temperatures. Glycine betaine, proline betaine, acetylcarnitine, carnitine, gamma-butyrobetaine and 3-dimethylsulphoniopropionate all acted as osmoprotectants, as evidenced by an increase in growth rate of L. monocytogenes 10403S and Scott A when provided with these compounds, while being stressed in defined medium containing 0.7 M NaCl. These same compounds exhibited cryoprotective activity, as evidenced by increasing the growth rate of L. monocytogenes at 5 degrees C. Ectoine, hydroxy ectoine, pipecolic acid and proline were ineffective as osmoprotectants or cryoprotectants under these conditions. The presence of osmoprotectants and cryoprotectants in foods may provide compounds assisting L. monocytogenes to overcome the barriers of high osmotic strength and low temperature that otherwise control microbial growth.
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Affiliation(s)
- D O Bayles
- Microbial Food Safety Research Unit, Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, Wyndmoor, PA, USA
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29
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Abstract
Bacteria can survive dramatic osmotic shifts. Osmoregulatory responses mitigate the passive adjustments in cell structure and the growth inhibition that may ensue. The levels of certain cytoplasmic solutes rise and fall in response to increases and decreases, respectively, in extracellular osmolality. Certain organic compounds are favored over ions as osmoregulatory solutes, although K+ fluxes are intrinsic to the osmoregulatory response for at least some organisms. Osmosensors must undergo transitions between "off" and "on" conformations in response to changes in extracellular water activity (direct osmosensing) or resulting changes in cell structure (indirect osmosensing). Those located in the cytoplasmic membranes and nucleoids of bacteria are positioned for indirect osmosensing. Cytoplasmic membrane-based osmosensors may detect changes in the periplasmic and/or cytoplasmic solvent by experiencing changes in preferential interactions with particular solvent constituents, cosolvent-induced hydration changes, and/or macromolecular crowding. Alternatively, the membrane may act as an antenna and osmosensors may detect changes in membrane structure. Cosolvents may modulate intrinsic biomembrane strain and/or topologically closed membrane systems may experience changes in mechanical strain in response to imposed osmotic shifts. The osmosensory mechanisms controlling membrane-based K+ transporters, transcriptional regulators, osmoprotectant transporters, and mechanosensitive channels intrinsic to the cytoplasmic membrane of Escherichia coli are under intensive investigation. The osmoprotectant transporter ProP and channel MscL act as osmosensors after purification and reconstitution in proteoliposomes. Evidence that sensor kinase KdpD receives multiple sensory inputs is consistent with the effects of K+ fluxes on nucleoid structure, cellular energetics, cytoplasmic ionic strength, and ion composition as well as on cytoplasmic osmolality. Thus, osmoregulatory responses accommodate and exploit the effects of individual cosolvents on cell structure and function as well as the collective contribution of cosolvents to intracellular osmolality.
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Affiliation(s)
- J M Wood
- Department of Microbiology and Guelph-Waterloo Centre for Graduate Work in Chemistry, University of Guelph, Guelph, Ontario, Canada N1G
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30
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Synthesis of glycine betaine from exogenous choline in the moderately halophilic bacterium halomonas elongata. Appl Environ Microbiol 1998; 64:4095-7. [PMID: 9758852 PMCID: PMC106611 DOI: 10.1128/aem.64.10.4095-4097.1998] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The role of choline in osmoprotection in the moderate halophile Halomonas elongata has been examined. Transport and conversion of choline to betaine began immediately after addition of choline to the growth medium. Intracellular accumulation of betaine synthesized from choline was salt dependent up to 2.5 M NaCl. Oxidation of choline was enhanced at 2.0 M NaCl in the presence or absence of externally provided betaine. This indicates that the NaCl concentration in the growth medium has major effects on the choline-betaine pathway of H. elongata.
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31
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Vijaranakul U, Xiong A, Lockwood K, Jayaswal RK. Cloning and nucleotide sequencing of a Staphylococcus aureus gene encoding a branched-chain-amino-acid transporter. Appl Environ Microbiol 1998; 64:763-7. [PMID: 9464420 PMCID: PMC106115 DOI: 10.1128/aem.64.2.763-767.1998] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We recently characterized a transposon-induced NaCl-sensitive mutant of Staphylococcus aureus (U. Vijaranakul, M. J. Nadakavukaren, D. O. Bayles, B. J. Wilkinson, and R. K. Jayaswal, Appl. Environ. Microbiol. 63:1889-1897, 1997). To further characterize this mutant, we determined the nucleotide sequence at the insertion site of the transposon on the S. aureus chromosome. Nucleotide sequencing revealed a 1,326-bp open reading frame (ORF442) encoding a hydrophobic 442-amino-acid polypeptide with a calculated molecular mass of 49,058 Da. The hydrophilicity profile of the gene product revealed the existence of 12 hydrophobic domains predicted to form membrane-associated alpha-helices. Comparison of the amino acid sequence of ORF442 with amino acid sequences in the GenBank database showed extensive homology with the branched-chain-amino-acid transport genes of gram-positive and gram-negative bacteria. This is the first brnQ gene in staphylococci to be described.
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Affiliation(s)
- U Vijaranakul
- Department of Biological Sciences, Illinois State University, Normal 61790-4120, USA
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