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Liu X, Van Maele L, Matarazzo L, Soulard D, Alves Duarte da Silva V, de Bakker V, Dénéréaz J, Bock FP, Taschner M, Ou J, Gruber S, Nizet V, Sirard JC, Veening JW. A conserved antigen induces respiratory Th17-mediated broad serotype protection against pneumococcal superinfection. Cell Host Microbe 2024; 32:304-314.e8. [PMID: 38417443 DOI: 10.1016/j.chom.2024.02.002] [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: 01/24/2023] [Revised: 12/06/2023] [Accepted: 02/05/2024] [Indexed: 03/01/2024]
Abstract
Several vaccines targeting bacterial pathogens show reduced efficacy upon concurrent viral infection, indicating that a new vaccinology approach is required. To identify antigens for the human pathogen Streptococcus pneumoniae that are effective following influenza infection, we performed CRISPRi-seq in a murine model of superinfection and identified the conserved lafB gene as crucial for virulence. We show that LafB is a membrane-associated, intracellular protein that catalyzes the formation of galactosyl-glucosyl-diacylglycerol, a glycolipid important for cell wall homeostasis. Respiratory vaccination with recombinant LafB, in contrast to subcutaneous vaccination, was highly protective against S. pneumoniae serotypes 2, 15A, and 24F in a murine model. In contrast to standard capsule-based vaccines, protection did not require LafB-specific antibodies but was dependent on airway CD4+ T helper 17 cells. Healthy human individuals can elicit LafB-specific immune responses, indicating LafB antigenicity in humans. Collectively, these findings present a universal pneumococcal vaccine antigen that remains effective following influenza infection.
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Affiliation(s)
- Xue Liu
- Department of Pathogen Biology, Base for International Science and Technology Cooperation, Carson Cancer Stem Cell Vaccines R&D Center, International Cancer Center, Shenzhen University Medical School, Shenzhen 518060, China; Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Laurye Van Maele
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, 59000 Lille, France
| | - Laura Matarazzo
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, 59000 Lille, France
| | - Daphnée Soulard
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, 59000 Lille, France
| | - Vinicius Alves Duarte da Silva
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, 59000 Lille, France
| | - Vincent de Bakker
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Julien Dénéréaz
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Florian P Bock
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Michael Taschner
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Jinzhao Ou
- Department of Pathogen Biology, Base for International Science and Technology Cooperation, Carson Cancer Stem Cell Vaccines R&D Center, International Cancer Center, Shenzhen University Medical School, Shenzhen 518060, China
| | - Stephan Gruber
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Victor Nizet
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, USA; Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Jean-Claude Sirard
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, 59000 Lille, France.
| | - Jan-Willem Veening
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland; Department of Pediatrics, University of California, San Diego, La Jolla, CA, USA.
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2
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van Wyk N, Badura J, von Wallbrunn C, Pretorius IS. Exploring future applications of the apiculate yeast Hanseniaspora. Crit Rev Biotechnol 2024; 44:100-119. [PMID: 36823717 DOI: 10.1080/07388551.2022.2136565] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 09/16/2022] [Accepted: 09/24/2022] [Indexed: 02/25/2023]
Abstract
As a metaphor, lemons get a bad rap; however the proverb 'if life gives you lemons, make lemonade' is often used in a motivational context. The same could be said of Hanseniaspora in winemaking. Despite its predominance in vineyards and grape must, this lemon-shaped yeast is underappreciated in terms of its contribution to the overall sensory profile of fine wine. Species belonging to this apiculate yeast are known for being common isolates not just on grape berries, but on many other fruits. They play a critical role in the early stages of a fermentation and can influence the quality of the final product. Their deliberate addition within mixed-culture fermentations shows promise in adding to the complexity of a wine and thus provide sensorial benefits. Hanseniaspora species are also key participants in the fermentations of a variety of other foodstuffs ranging from chocolate to apple cider. Outside of their role in fermentation, Hanseniaspora species have attractive biotechnological possibilities as revealed through studies on biocontrol potential, use as a whole-cell biocatalyst and important interactions with Drosophila flies. The growing amount of 'omics data on Hanseniaspora is revealing interesting features of the genus that sets it apart from the other Ascomycetes. This review collates the fields of research conducted on this apiculate yeast genus.
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Affiliation(s)
- Niël van Wyk
- Department of Microbiology and Biochemistry, Hochschule Geisenheim University, Geisenheim, Germany
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia
| | - Jennifer Badura
- Department of Microbiology and Biochemistry, Hochschule Geisenheim University, Geisenheim, Germany
| | - Christian von Wallbrunn
- Department of Microbiology and Biochemistry, Hochschule Geisenheim University, Geisenheim, Germany
| | - Isak S Pretorius
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia
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3
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Zhang Y, Chen R, Zhang D, Qi S, Liu Y. Metabolite interactions between host and microbiota during health and disease: Which feeds the other? Biomed Pharmacother 2023; 160:114295. [PMID: 36709600 DOI: 10.1016/j.biopha.2023.114295] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/20/2023] [Accepted: 01/20/2023] [Indexed: 01/30/2023] Open
Abstract
Metabolites produced by the host and microbiota play a crucial role in how human bodies develop and remain healthy. Most of these metabolites are produced by microbiota and hosts in the digestive tract. Metabolites in the gut have important roles in energy metabolism, cellular communication, and host immunity, among other physiological activities. Although numerous host metabolites, such as free fatty acids, amino acids, and vitamins, are found in the intestine, metabolites generated by gut microbiota are equally vital for intestinal homeostasis. Furthermore, microbiota in the gut is the sole source of some metabolites, including short-chain fatty acids (SCFAs). Metabolites produced by microbiota, such as neurotransmitters and hormones, may modulate and significantly affect host metabolism. The gut microbiota is becoming recognized as a second endocrine system. A variety of chronic inflammatory disorders have been linked to aberrant host-microbiota interplays, but the precise mechanisms underpinning these disturbances and how they might lead to diseases remain to be fully elucidated. Microbiome-modulated metabolites are promising targets for new drug discovery due to their endocrine function in various complex disorders. In humans, metabolotherapy for the prevention or treatment of various disorders will be possible if we better understand the metabolic preferences of bacteria and the host in specific tissues and organs. Better disease treatments may be possible with the help of novel complementary therapies that target host or bacterial metabolism. The metabolites, their physiological consequences, and functional mechanisms of the host-microbiota interplays will be highlighted, summarized, and discussed in this overview.
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Affiliation(s)
- Yan Zhang
- Department of Anethesiology, China-Japan Union Hospital of Jilin University, Changchun 130033, People's Republic of China.
| | - Rui Chen
- Department of Pediatrics, China-Japan Union Hospital of Jilin University, Changchun 130033, People's Republic of China.
| | - DuoDuo Zhang
- Department of Thoracic Surgery, The First Hospital of Jilin University, Changchun, Jilin Province 130021, People's Republic of China.
| | - Shuang Qi
- Department of Anethesiology, China-Japan Union Hospital of Jilin University, Changchun 130033, People's Republic of China.
| | - Yan Liu
- Department of Hand and Foot Surgery, China-Japan Union Hospital of Jilin University, Changchun 130033, People's Republic of China.
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Li L, Ma J, Yu Z, Li M, Zhang W, Sun H. Epidemiological characteristics and antibiotic resistance mechanisms of Streptococcus pneumoniae: An updated review. Microbiol Res 2023; 266:127221. [DOI: 10.1016/j.micres.2022.127221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 09/13/2022] [Accepted: 10/03/2022] [Indexed: 11/27/2022]
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Locke AK, Zaki FR, Fitzgerald ST, Sudhir K, Monroy GL, Choi H, Won J, Mahadevan-Jansen A, Boppart SA. Differentiation of otitis media-causing bacteria and biofilms via Raman spectroscopy and optical coherence tomography. Front Cell Infect Microbiol 2022; 12:869761. [PMID: 36034696 PMCID: PMC9400059 DOI: 10.3389/fcimb.2022.869761] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 06/30/2022] [Indexed: 11/25/2022] Open
Abstract
In the management of otitis media (OM), identification of causative bacterial pathogens and knowledge of their biofilm formation can provide more targeted treatment approaches. Current clinical diagnostic methods rely on the visualization of the tympanic membrane and lack real-time assessment of the causative pathogen(s) and the nature of any biofilm that may reside behind the membrane and within the middle ear cavity. In recent years, optical coherence tomography (OCT) has been demonstrated as an improved in vivo diagnostic tool for visualization and morphological characterization of OM biofilms and middle ear effusions; but lacks specificity about the causative bacterial species. This study proposes the combination of OCT and Raman spectroscopy (RS) to examine differences in the refractive index, optical attenuation, and biochemical composition of Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, and Pseudomonas aeruginosa; four of the leading otopathogens in OM. This combination provides a dual optical approach for identifying and differentiating OM-causing bacterial species under three different in vitro growth environments (i.e., agar-grown colonies, planktonic cells from liquid cultures, and biofilms). This study showed that RS was able to identify key biochemical variations to differentiate all four OM-causing bacteria. Additionally, biochemical spectral changes (RS) and differences in the mean attenuation coefficient (OCT) were able to distinguish the growth environment for each bacterial species.
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Affiliation(s)
- Andrea K. Locke
- Vanderbilt Biophotonics Center, School of Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Chemistry, College of Arts and Science, Vanderbilt University, Nashville, TN, United States
| | - Farzana R. Zaki
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL, United States
| | - Sean T. Fitzgerald
- Vanderbilt Biophotonics Center, School of Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, TN, United States
| | - Kavya Sudhir
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL, United States
- Department of Bioengineering, The Grainger College of Engineering, University of Illinois at Urbana–Champaign, Urbana, IL, United States
| | - Guillermo L. Monroy
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL, United States
| | - Honggu Choi
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL, United States
| | - Jungeun Won
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL, United States
- Department of Bioengineering, The Grainger College of Engineering, University of Illinois at Urbana–Champaign, Urbana, IL, United States
| | - Anita Mahadevan-Jansen
- Vanderbilt Biophotonics Center, School of Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Otolaryngology - Head & Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, TN, United States
- *Correspondence: Stephen A. Boppart, ; Anita Mahadevan-Jansen,
| | - Stephen A. Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL, United States
- Department of Bioengineering, The Grainger College of Engineering, University of Illinois at Urbana–Champaign, Urbana, IL, United States
- Carle Illinois College of Medicine, University of Illinois at Urbana–Champaign, Urbana, IL, United States
- Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign, Urbana, IL, United States
- *Correspondence: Stephen A. Boppart, ; Anita Mahadevan-Jansen,
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Ulrych A, Fabrik I, Kupčík R, Vajrychová M, Doubravová L, Branny P. Cell Wall Stress Stimulates the Activity of the Protein Kinase StkP of Streptococcus pneumoniae, Leading to Multiple Phosphorylation. J Mol Biol 2021; 433:167319. [PMID: 34688688 DOI: 10.1016/j.jmb.2021.167319] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 10/06/2021] [Accepted: 10/15/2021] [Indexed: 12/28/2022]
Abstract
Streptococcus pneumoniae is an opportunistic human pathogen that encodes a single eukaryotic-type Ser/Thr protein kinase StkP and its functional counterpart, the protein phosphatase PhpP. These signaling enzymes play critical roles in coordinating cell division and growth in pneumococci. In this study, we determined the proteome and phosphoproteome profiles of relevant mutants. Comparison of those with the wild-type provided a representative dataset of novel phosphoacceptor sites and StkP-dependent substrates. StkP phosphorylates key proteins involved in cell division and cell wall biosynthesis in both the unencapsulated laboratory strain Rx1 and the encapsulated virulent strain D39. Furthermore, we show that StkP plays an important role in triggering an adaptive response induced by a cell wall-directed antibiotic. Phosphorylation of the sensor histidine kinase WalK and downregulation of proteins of the WalRK core regulon suggest crosstalk between StkP and the WalRK two-component system. Analysis of proteomic profiles led to the identification of gene clusters regulated by catabolite control mechanisms, indicating a tight coupling of carbon metabolism and cell wall homeostasis. The imbalance of steady-state protein phosphorylation in the mutants as well as after antibiotic treatment is accompanied by an accumulation of the global Spx regulator, indicating a Spx-mediated envelope stress response. In summary, StkP relays the perceived signal of cell wall status to key cell division and regulatory proteins, controlling the cell cycle and cell wall homeostasis.
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Affiliation(s)
- Aleš Ulrych
- Institute of Microbiology, v.v.i., Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic.
| | - Ivo Fabrik
- Biomedical Research Center, University Hospital Hradec Králové, Sokolská 581, 500 05 Hradec Králové, Czech Republic.
| | - Rudolf Kupčík
- Biomedical Research Center, University Hospital Hradec Králové, Sokolská 581, 500 05 Hradec Králové, Czech Republic.
| | - Marie Vajrychová
- Biomedical Research Center, University Hospital Hradec Králové, Sokolská 581, 500 05 Hradec Králové, Czech Republic.
| | - Linda Doubravová
- Institute of Microbiology, v.v.i., Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic.
| | - Pavel Branny
- Institute of Microbiology, v.v.i., Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic.
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Inactivation of Transcriptional Regulator FabT Influences Colony Phase Variation of Streptococcus pneumoniae. mBio 2021; 12:e0130421. [PMID: 34399624 PMCID: PMC8406281 DOI: 10.1128/mbio.01304-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Streptococcus pneumoniae is an opportunistic pathogen that can alter its cell surface phenotype in response to the host environment. We demonstrated that the transcriptional regulator FabT is an indirect regulator of capsular polysaccharide, an important virulence factor of Streptococcus pneumoniae. Transcriptome analysis between the wild-type D39s and D39ΔfabT mutant strains unexpectedly identified a differentially expressed gene encoding a site-specific recombinase, PsrA. PsrA catalyzes the inversion of 3 homologous hsdS genes in a type I restriction-modification (RM) system SpnD39III locus and is responsible for the reversible switch of phase variation. Our study demonstrated that upregulation of PsrA in a D39ΔfabT mutant correlated with an increased ratio of transparent (T) phase variants. Inactivation of the invertase PsrA led to uniform opaque (O) variants. Direct quantification of allelic variants of hsdS derivatives and inversions of inverted repeats indicated that the recombinase PsrA fully catalyzes the inversion mediated by IR1 and IR3, and FabT mediated the recombination of the hsdS alleles in PsrA-dependent and PsrA-independent manners. In addition, compared to D39s, the ΔfabT mutant exhibited reduced nasopharyngeal colonization and was more resistant to phagocytosis and less adhesive to epithelial cells. These results indicated that phase variation in the ΔfabT mutant also affects other cell surface components involved in host interactions.
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Peters K, Schweizer I, Hakenbeck R, Denapaite D. New Insights into Beta-Lactam Resistance of Streptococcus pneumoniae: Serine Protease HtrA Degrades Altered Penicillin-Binding Protein 2x. Microorganisms 2021; 9:microorganisms9081685. [PMID: 34442764 PMCID: PMC8400419 DOI: 10.3390/microorganisms9081685] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 08/02/2021] [Accepted: 08/04/2021] [Indexed: 11/18/2022] Open
Abstract
Reduced amounts of the essential penicillin-binding protein 2x (PBP2x) were detected in two cefotaxime-resistant Streptococcus pneumoniae laboratory mutants C405 and C606. These mutants contain two or four mutations in the penicillin-binding domain of PBP2x, respectively. The transcription of the pbp2x gene was not affected in both mutants; thus, the reduced PBP2x amounts were likely due to post-transcriptional regulation. The mutants carry a mutation in the histidine protein kinase gene ciaH, resulting in enhanced gene expression mediated by the cognate response regulator CiaR. Deletion of htrA, encoding a serine protease regulated by CiaR, or inactivation of HtrA proteolytic activity showed that HtrA is indeed responsible for PBP2x degradation in both mutants, and that this affects β-lactam resistance. Depletion of the PBP2xC405 in different genetic backgrounds confirmed that HtrA degrades PBP2xC405. A GFP-PBP2xC405 fusion protein still localized at the septum in the absence of HtrA. The complementation studies in HtrA deletion strains showed that HtrA can be overexpressed in pneumococcal cells to specific levels, depending on the genetic background. Quantitative Western blotting revealed that the PBP2x amount in C405 strain was less than 20% compared to parental strain, suggesting that PBP2x is an abundant protein in S. pneumoniae R6 strain.
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Neville SL, Sjöhamn J, Watts JA, MacDermott-Opeskin H, Fairweather SJ, Ganio K, Carey Hulyer A, McGrath AP, Hayes AJ, Malcolm TR, Davies MR, Nomura N, Iwata S, O'Mara ML, Maher MJ, McDevitt CA. The structural basis of bacterial manganese import. SCIENCE ADVANCES 2021; 7:7/32/eabg3980. [PMID: 34362732 PMCID: PMC8346216 DOI: 10.1126/sciadv.abg3980] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 06/10/2021] [Indexed: 05/23/2023]
Abstract
Metal ions are essential for all forms of life. In prokaryotes, ATP-binding cassette (ABC) permeases serve as the primary import pathway for many micronutrients including the first-row transition metal manganese. However, the structural features of ionic metal transporting ABC permeases have remained undefined. Here, we present the crystal structure of the manganese transporter PsaBC from Streptococcus pneumoniae in an open-inward conformation. The type II transporter has a tightly closed transmembrane channel due to "extracellular gating" residues that prevent water permeation or ion reflux. Below these residues, the channel contains a hitherto unreported metal coordination site, which is essential for manganese translocation. Mutagenesis of the extracellular gate perturbs manganese uptake, while coordination site mutagenesis abolishes import. These structural features are highly conserved in metal-specific ABC transporters and are represented throughout the kingdoms of life. Collectively, our results define the structure of PsaBC and reveal the features required for divalent cation transport.
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Affiliation(s)
- Stephanie L Neville
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jennie Sjöhamn
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Jacinta A Watts
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | | | - Stephen J Fairweather
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Katherine Ganio
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Alex Carey Hulyer
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Aaron P McGrath
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Andrew J Hayes
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Tess R Malcolm
- School of Chemistry and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Mark R Davies
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Norimichi Nomura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - So Iwata
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- Research Acceleration Program, Membrane Protein Crystallography Project, Japan Science and Technology Agency, Kyoto, Japan
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, Japan
| | - Megan L O'Mara
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia
| | - Megan J Maher
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia.
- School of Chemistry and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher A McDevitt
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia.
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Gisch N, Peters K, Thomsen S, Vollmer W, Schwudke D, Denapaite D. Commensal Streptococcus mitis produces two different lipoteichoic acids of type I and type IV. Glycobiology 2021; 31:1655-1669. [PMID: 34314482 DOI: 10.1093/glycob/cwab079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/16/2021] [Accepted: 07/14/2021] [Indexed: 11/14/2022] Open
Abstract
The opportunistic pathogen Streptococcus mitis possesses, like other members of the Mitis group of viridans streptococci, phosphorylcholine (P-Cho)-containing teichoic acids (TAs) in its cell wall. Bioinformatic analyses predicted the presence of TAs that are almost identical with those identified in the pathogen S. pneumoniae, but a detailed analysis of S. mitis lipoteichoic acid (LTA) was not performed to date. Here we determined the structures of LTA from two S. mitis strains, the high-level beta-lactam and multiple antibiotic resistant strain B6 and the penicillin-sensitive strain NCTC10712. In agreement with bioinformatic predictions we found that the structure of one LTA (type IV) was like pneumococcal LTA, except the exchange of a glucose moiety with a galactose within the repeating units. Further genome comparisons suggested that the majority of S. mitis strains should contain the same type IV LTA as S. pneumoniae, providing a more complete understanding of the biosynthesis of these P-Cho-containing TAs in members of the Mitis group of streptococci. Remarkably, we observed besides type IV LTA an additional polymer belonging to LTA type I in both investigated S. mitis strains. This LTA consists of β-galactofuranosyl-(1,3)-diacylglycerol as glycolipid anchor and a poly-glycerol-phosphate chain at the O-6 position of the furanosidic galactose. Hence, these bacteria are capable of synthesizing two different LTA polymers, most likely produced by distinct biosynthesis pathways. Our bioinformatics analysis revealed the prevalence of the LTA synthase LtaS, most probably responsible for the second LTA version (type I), amongst S. mitis and S. pseudopneumoniae strains.
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Affiliation(s)
- Nicolas Gisch
- Division of Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Katharina Peters
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, NE2 4AX Newcastle upon Tyne, UK
| | - Simone Thomsen
- Division of Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, NE2 4AX Newcastle upon Tyne, UK
| | - Dominik Schwudke
- Division of Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany.,German Center for Infection Research (DZIF), Thematic Translational Unit Tuberculosis, Partner Site: Hamburg-Lübeck-Borstel-Riems, 23845 Borstel, Germany.,Airway Research Center North, Member of the German Center for Lung Research (DZL), 23845 Borstel, Germany
| | - Dalia Denapaite
- Department of Microbiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
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11
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Joyce LR, Guan Z, Palmer KL. Streptococcus pneumoniae, S. pyogenes and S. agalactiae membrane phospholipid remodelling in response to human serum. MICROBIOLOGY-SGM 2021; 167. [PMID: 33983874 PMCID: PMC8290102 DOI: 10.1099/mic.0.001048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Streptococcus pneumoniae, S. pyogenes (Group A Streptococcus; GAS) and S. agalactiae (Group B Streptococcus; GBS) are major aetiological agents of diseases in humans. The cellular membrane, a crucial site in host–pathogen interactions, is poorly characterized in streptococci. Moreover, little is known about whether or how environmental conditions influence their lipid compositions. Using normal phase liquid chromatography coupled with electrospray ionization MS, we characterized the phospholipids and glycolipids of S. pneumoniae, GAS and GBS in routine undefined laboratory medium, streptococcal defined medium and, in order to mimic the host environment, defined medium supplemented with human serum. In human serum-supplemented medium, all three streptococcal species synthesize phosphatidylcholine (PC), a zwitterionic phospholipid commonly found in eukaryotes but relatively rare in bacteria. We previously reported that S. pneumoniae utilizes the glycerophosphocholine (GPC) biosynthetic pathway to synthesize PC. Through substrate tracing experiments, we confirm that GAS and GBS scavenge lysoPC, a major metabolite in human serum, thereby using an abbreviated GPC pathway for PC biosynthesis. Furthermore, we found that plasmanyl-PC is uniquely present in the GBS membrane during growth with human serum, suggesting GBS possesses unusual membrane biochemical or biophysical properties. In summary, we report cellular lipid remodelling by the major pathogenic streptococci in response to metabolites present in human serum.
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Affiliation(s)
- Luke R Joyce
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
| | - Kelli L Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
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Knaack W, Hölzl G, Gisch N. Structural Analysis of Glycosylglycerolipids Using NMR Spectroscopy. Methods Mol Biol 2021; 2295:249-272. [PMID: 34047981 DOI: 10.1007/978-1-0716-1362-7_14] [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] [Indexed: 06/12/2023]
Abstract
Glycosylglycerolipids are essential components of plant and bacterial membranes. These lipids exert central roles in physiological processes such as photosynthesis in plants or to maintain membrane stability in bacteria. They are composed of a glycerol backbone esterified with two fatty acids at the sn-1 and sn-2 positions, and carbohydrate moieties connected via a glycosidic bond at the sn-3 position. Nuclear magnetic resonance (NMR) spectroscopy is a state-of-the-art technique to determine the nature of the bound carbohydrates as well as their anomeric configurations. Here we describe the analysis of intact glycosylglycerolipids by NMR spectroscopy to determine structural details of their sugar head groups without the need of chemical derivatization.
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Affiliation(s)
- Wiebke Knaack
- Division of Bioanalytical Chemistry, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Georg Hölzl
- Institute of Molecular Physiology and Biotechnology of Plants (IMBIO), University of Bonn, Bonn, Germany
| | - Nicolas Gisch
- Division of Bioanalytical Chemistry, Research Center Borstel, Leibniz Lung Center, Borstel, Germany.
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13
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Phosphatidylcholine Biosynthesis in Mitis Group Streptococci via Host Metabolite Scavenging. J Bacteriol 2019; 201:JB.00495-19. [PMID: 31501281 PMCID: PMC6805115 DOI: 10.1128/jb.00495-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 08/29/2019] [Indexed: 01/21/2023] Open
Abstract
We lack fundamental information about the composition of the cellular membrane even for the best-studied pathogens of critical significance for human health. The mitis group streptococci are closely linked to humans in health and disease, but their membrane biology is poorly understood. Here, we demonstrate that these streptococci scavenge major human metabolites and use them to synthesize the membrane phospholipid PC. Our work is significant because it identifies a mechanism by which the major human pathogen S. pneumoniae and the primary human oral colonizers S. mitis and S. oralis remodel their membranes in response to host metabolites. The mitis group streptococci include the major human pathogen Streptococcus pneumoniae and the opportunistic pathogens Streptococcus mitis and Streptococcus oralis, which are human oral cavity colonizers and agents of bacteremia and infective endocarditis in immunocompromised patients. Bacterial membrane lipids play crucial roles in microbe-host interactions; for many pathogens, however, the composition of the membrane is poorly understood. In this study, we characterized the lipidomes of selected species of mitis group streptococci and investigated the mechanistic basis for biosynthesis of the phospholipid phosphatidylcholine (PC). PC is a major lipid in eukaryotic cellular membranes, but it is considered to be comparatively rare in bacterial taxa. Using liquid chromatography-mass spectrometry in conjunction with stable isotope tracing, we determined that mitis group streptococci synthesize PC via a rare host-metabolite-scavenging pathway, the glycerophosphocholine (GPC) pathway, which is largely uncharacterized in bacteria. Our work demonstrates that mitis group streptococci, including S. pneumoniae, remodel their membranes in response to the major human metabolites GPC and lysophosphatidylcholine. IMPORTANCE We lack fundamental information about the composition of the cellular membrane even for the best-studied pathogens of critical significance for human health. The mitis group streptococci are closely linked to humans in health and disease, but their membrane biology is poorly understood. Here, we demonstrate that these streptococci scavenge major human metabolites and use them to synthesize the membrane phospholipid PC. Our work is significant because it identifies a mechanism by which the major human pathogen S. pneumoniae and the primary human oral colonizers S. mitis and S. oralis remodel their membranes in response to host metabolites.
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Lipidomic signature of Bacillus licheniformis I89 during the different growth phases unravelled by high-resolution liquid chromatography-mass spectrometry. Arch Biochem Biophys 2019; 663:83-94. [DOI: 10.1016/j.abb.2018.12.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/04/2018] [Accepted: 12/21/2018] [Indexed: 11/19/2022]
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Spencer C, Bensing BA, Mishra NN, Sullam PM. Membrane trafficking of the bacterial adhesin GspB and the accessory Sec transport machinery. J Biol Chem 2018; 294:1502-1515. [PMID: 30514759 DOI: 10.1074/jbc.ra118.005657] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 11/14/2018] [Indexed: 12/14/2022] Open
Abstract
The serine-rich repeat (SRR) glycoproteins of Gram-positive bacteria are large, cell wall-anchored adhesins that mediate binding to many host cells and proteins and are associated with bacterial virulence. SRR glycoproteins are exported to the cell surface by the accessory Sec (aSec) system comprising SecA2, SecY2, and 3-5 additional proteins (Asp1 to Asp5) that are required for substrate export. These adhesins typically have a 90-amino acid-long signal peptide containing an elongated N-region and a hydrophobic core. Previous studies of GspB (the SRR adhesin of Streptococcus gordonii) have shown that a glycine-rich motif in its hydrophobic core is essential for selective, aSec-mediated transport. However, the role of this extended N-region in transport is poorly understood. Here, using protein-lipid co-flotation assays and site-directed mutagenesis, we report that the N-region of the GspB signal peptide interacts with anionic lipids through electrostatic forces and that this interaction is necessary for GspB preprotein trafficking to lipid membranes. Moreover, we observed that protein-lipid binding is required for engagement of GspB with SecA2 and for aSec-mediated transport. We further found that SecA2 and Asp1 to Asp3 also localize selectively to liposomes that contain anionic lipids. These findings suggest that the GspB signal peptide electrostatically binds anionic lipids at the cell membrane, where it encounters SecA2. After SecA2 engagement with the signal peptide, Asp1 to Asp3 promote SecA2 engagement with the mature domain, which activates GspB translocation.
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Affiliation(s)
- Cierra Spencer
- Division of Infectious Diseases, San Francisco Veterans Affairs Medical Center, San Francisco, California 94121; Department of Medicine, University of California, San Francisco, California 94143
| | - Barbara A Bensing
- Division of Infectious Diseases, San Francisco Veterans Affairs Medical Center, San Francisco, California 94121; Department of Medicine, University of California, San Francisco, California 94143
| | - Nagendra N Mishra
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute, Torrance, California 90502; David Geffen School of Medicine, UCLA, Los Angeles, California 90095
| | - Paul M Sullam
- Division of Infectious Diseases, San Francisco Veterans Affairs Medical Center, San Francisco, California 94121; Department of Medicine, University of California, San Francisco, California 94143.
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Tong L, Zhang M, Zhang X, Wang Y, Ou D, Zhang J, Wu Q, Ye Y. Exploration of factors in response to low acid tolerance using random mutagenesis in Cronobacter malonaticus. Food Res Int 2018; 116:994-999. [PMID: 30717032 DOI: 10.1016/j.foodres.2018.09.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 08/26/2018] [Accepted: 09/13/2018] [Indexed: 11/25/2022]
Abstract
Cronobacter species are associated with rare but severe infections in newborns, and their tolerance to environmental stress such as acid stress has been described. However, the factors involved in low acid tolerance in Cronobacter are poorly understood. Here, a transposon mutagenesis approach was used to explore the factors involved in acid tolerance in C. malonaticus. Eight mutants from mutant library (n = 215) were successfully screened through a comparison of growth with wild type (WT) strain under acid stress (pH 4.0). Eight mutating sites including glucosyltransferase MdoH, extracellular serine protease, sulfate transporter, phosphate transporter permease subunit PstC, lysine transporter, nitrogen regulation protein NR (II), D-alanine-D-alanine ligase, glucan biosynthesis protein G were successfully identified by arbitrary polymerase chain reaction and sequencing. The biomass of biofilm of eight mutants were significantly reduced using crystal violet staining (CVS) compared with that of WT. furthermore, the more compact biofilms of WT was observed than those of eight mutants through scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). Disassembly of biofilms appeared among mutants and WT strain from 48 h to 72 h through the increasing of dead cells and reduction of viable cells and exopolysaccharide. The study reveals the molecular basis involved in acid tolerance of C. malonaticus and a possible relationship between biofilm formation and acid tolerance, which provides valuable information for survival of C. malonaticus under acid stress.
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Affiliation(s)
- Liaowang Tong
- School of Food Science and Engineering, Hefei University of Technology, Hefei 230009, China; State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou 510070, China
| | - Maofeng Zhang
- School of Food Science and Engineering, Hefei University of Technology, Hefei 230009, China; State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou 510070, China
| | - Xiyan Zhang
- School of Food Science and Engineering, Hefei University of Technology, Hefei 230009, China
| | - Yaping Wang
- School of Food Science and Engineering, Hefei University of Technology, Hefei 230009, China
| | - Dexin Ou
- School of Food Science and Engineering, Hefei University of Technology, Hefei 230009, China
| | - Jumei Zhang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou 510070, China
| | - Qingping Wu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou 510070, China.
| | - Yingwang Ye
- School of Food Science and Engineering, Hefei University of Technology, Hefei 230009, China; State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou 510070, China.
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Theilacker C, Diederich AK, Otto A, Sava IG, Wobser D, Bao Y, Hese K, Broszat M, Henneke P, Becher D, Huebner J. Enterococcus faecalis Glycolipids Modulate Lipoprotein-Content of the Bacterial Cell Membrane and Host Immune Response. PLoS One 2015; 10:e0132949. [PMID: 26172831 PMCID: PMC4501811 DOI: 10.1371/journal.pone.0132949] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Accepted: 06/21/2015] [Indexed: 12/25/2022] Open
Abstract
In this study, we investigated the impact of the cell membrane composition of E. faecalis on its recognition by the host immune system. To this end, we employed an E. faecalis deletion mutant (ΔbgsA) that does not synthesize the major cell membrane glycolipid diglycosyl-diacylglycerol (DGlcDAG). Proteomic analysis revealed that 13 of a total of 21 upregulated surface-associated proteins of E. faecalis ΔbgsA were lipoproteins. This led to a total lipoprotein content in the cell membrane of 35.8% in ΔbgsA compared to only 9.4% in wild-type bacteria. Increased lipoprotein content strongly affected the recognition of ΔbgsA by mouse macrophages in vitro with an increased stimulation of TNF-α production by heat-fixed bacteria and secreted antigens. Inactivation of the prolipoprotein diacylglycerol transferase (lgt) in ΔbgsA abrogated TNF-α induction by a ΔbgsA_lgt double mutant indicating that lipoproteins mediate increased activation of mouse macrophages by ΔbgsA. Heat-fixed ΔbgsA bacteria, culture supernatant, or cell membrane lipid extract activated transfected HEK cells in a TLR2-dependent fashion; the same was not true of wild-type bacteria. In mice infected intraperitoneally with a sublethal dose of E. faecalis we observed a 70% greater mortality in mice infected with ΔbgsA compared with wild-type-infected mice. Increased mortality due to ΔbgsA infection was associated with elevated plasma levels of the inflammatory cytokines TNF-α, IL-6 and MIP-2. In summary, our results provide evidence that an E. faecalis mutant lacking its major bilayer forming glycolipid DGlcDAG upregulates lipoprotein expression leading to increased activation of the host innate immune system and virulence in vivo.
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Affiliation(s)
- Christian Theilacker
- Center for Chronic Immunodeficiency (CCI), University Medical Center Freiburg, Freiburg, Germany
- Center for Infectious Disease and Travel Medicine, University Medical Center Freiburg, Freiburg, Germany
- * E-mail:
| | - Ann-Kristin Diederich
- Center for Infectious Disease and Travel Medicine, University Medical Center Freiburg, Freiburg, Germany
- Division of Pediatric Infectious Diseases, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
- Department of Microbiology, Faculty of Biology, Albert-Ludwigs-University, Freiburg, Germany
| | - Andreas Otto
- Institute for Microbiology, Department of Microbial Physiology, Ernst-Moritz-Arndt-University, Greifswald, Germany
| | - Irina G. Sava
- Research Center for Nutrition and Food Science, Technical University Munich, Freising, Germany
| | - Dominique Wobser
- Center for Infectious Disease and Travel Medicine, University Medical Center Freiburg, Freiburg, Germany
| | - Yinyin Bao
- Center for Infectious Disease and Travel Medicine, University Medical Center Freiburg, Freiburg, Germany
| | - Katrin Hese
- Center for Chronic Immunodeficiency (CCI), University Medical Center Freiburg, Freiburg, Germany
| | - Melanie Broszat
- Center for Infectious Disease and Travel Medicine, University Medical Center Freiburg, Freiburg, Germany
| | - Philipp Henneke
- Center for Chronic Immunodeficiency (CCI), University Medical Center Freiburg, Freiburg, Germany
- Center for Paediatrics and Adolescent Medicine, University Medical Center Freiburg, Freiburg, Germany
| | - Dörte Becher
- Institute for Microbiology, Department of Microbial Physiology, Ernst-Moritz-Arndt-University, Greifswald, Germany
| | - Johannes Huebner
- Center for Infectious Disease and Travel Medicine, University Medical Center Freiburg, Freiburg, Germany
- Division of Pediatric Infectious Diseases, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
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Sohlenkamp C, Geiger O. Bacterial membrane lipids: diversity in structures and pathways. FEMS Microbiol Rev 2015; 40:133-59. [DOI: 10.1093/femsre/fuv008] [Citation(s) in RCA: 571] [Impact Index Per Article: 63.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2015] [Indexed: 12/22/2022] Open
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Delorme C, Abraham AL, Renault P, Guédon E. Genomics of Streptococcus salivarius, a major human commensal. INFECTION GENETICS AND EVOLUTION 2014; 33:381-92. [PMID: 25311532 DOI: 10.1016/j.meegid.2014.10.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 09/30/2014] [Accepted: 10/02/2014] [Indexed: 10/24/2022]
Abstract
The salivarius group of streptococci is of particular importance for humans. This group consists of three genetically similar species, Streptococcus salivarius, Streptococcus vestibularis and Streptococcus thermophilus. S. salivarius and S. vestibularis are commensal organisms that may occasionally cause opportunistic infections in humans, whereas S. thermophilus is a food bacterium widely used in dairy production. We developed Multilocus sequence typing (MLST) and comparative genomic analysis to confirm the clear separation of these three species. These analyses also identified a subgroup of four strains, with a core genome diverging by about 10%, in terms of its nucleotide sequence, from that of S. salivarius sensu stricto. S. thermophilus species displays a low level of nucleotide variability, due to its recent emergence with the development of agriculture. By contrast, nucleotide variability is high in the other two species of the salivarius group, reflecting their long-standing association with humans. The species of the salivarius group have genome sizes ranging from the smallest (∼ 1.7 Mb for S. thermophilus) to the largest (∼ 2.3 Mb for S. salivarius) among streptococci, reflecting genome reduction linked to a narrow, nutritionally rich environment for S. thermophilus, and natural, more competitive niches for the other two species. Analyses of genomic content have indicated that the core genes of S. salivarius account for about two thirds of the genome, indicating considerable variability of gene content and differences in potential adaptive features. Furthermore, we showed that the genome of this species is exceptionally rich in genes encoding surface factors, glycosyltransferases and response regulators. Evidence of widespread genetic exchanges was obtained, probably involving a natural competence system and the presence of diverse mobile elements. However, although the S. salivarius strains studied were isolated from several human body-related sites (all levels of the digestive tract, skin, breast milk, and body fluids) and included clinical strains, no genetic or genomic niche-specific features could be identified to discriminate specific group.
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Affiliation(s)
- Christine Delorme
- INRA, UMR 1319 Micalis, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR MICALIS, Jouy-en-Josas, France
| | - Anne-Laure Abraham
- INRA, UMR 1319 Micalis, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR MICALIS, Jouy-en-Josas, France
| | - Pierre Renault
- INRA, UMR 1319 Micalis, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR MICALIS, Jouy-en-Josas, France
| | - Eric Guédon
- INRA, UMR 1319 Micalis, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR MICALIS, Jouy-en-Josas, France.
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