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Oles RE, Carrillo Terrazas M, Loomis LR, Hsu CY, Tribelhorn C, Belda-Ferre P, Ea AC, Bryant M, Young JA, Carrow HC, Sandborn WJ, Dulai PS, Sivagnanam M, Pride D, Knight R, Chu H. Pangenome comparison of Bacteroides fragilis genomospecies unveils genetic diversity and ecological insights. mSystems 2024; 9:e0051624. [PMID: 38934546 PMCID: PMC11265264 DOI: 10.1128/msystems.00516-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024] Open
Abstract
Bacteroides fragilis is a Gram-negative commensal bacterium commonly found in the human colon, which differentiates into two genomospecies termed divisions I and II. Through a comprehensive collection of 694 B. fragilis whole genome sequences, we identify novel features distinguishing these divisions. Our study reveals a distinct geographic distribution with division I strains predominantly found in North America and division II strains in Asia. Additionally, division II strains are more frequently associated with bloodstream infections, suggesting a distinct pathogenic potential. We report differences between the two divisions in gene abundance related to metabolism, virulence, stress response, and colonization strategies. Notably, division II strains harbor more antimicrobial resistance (AMR) genes than division I strains. These findings offer new insights into the functional roles of division I and II strains, indicating specialized niches within the intestine and potential pathogenic roles in extraintestinal sites. IMPORTANCE Understanding the distinct functions of microbial species in the gut microbiome is crucial for deciphering their impact on human health. Classifying division II strains as Bacteroides fragilis can lead to erroneous associations, as researchers may mistakenly attribute characteristics observed in division II strains to the more extensively studied division I B. fragilis. Our findings underscore the necessity of recognizing these divisions as separate species with distinct functions. We unveil new findings of differential gene prevalence between division I and II strains in genes associated with intestinal colonization and survival strategies, potentially influencing their role as gut commensals and their pathogenicity in extraintestinal sites. Despite the significant niche overlap and colonization patterns between these groups, our study highlights the complex dynamics that govern strain distribution and behavior, emphasizing the need for a nuanced understanding of these microorganisms.
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Affiliation(s)
- Renee E. Oles
- Department of Pathology, University of California, San Diego, California, USA
- Department of Pediatrics, School of Medicine, University of California, San Diego, California, USA
| | | | - Luke R. Loomis
- Department of Pathology, University of California, San Diego, California, USA
| | - Chia-Yun Hsu
- Department of Pathology, University of California, San Diego, California, USA
| | - Caitlin Tribelhorn
- Department of Pediatrics, School of Medicine, University of California, San Diego, California, USA
| | - Pedro Belda-Ferre
- Department of Pediatrics, School of Medicine, University of California, San Diego, California, USA
| | - Allison C. Ea
- Department of Pathology, University of California, San Diego, California, USA
| | - MacKenzie Bryant
- Department of Pediatrics, School of Medicine, University of California, San Diego, California, USA
| | - Jocelyn A. Young
- Department of Pediatrics, School of Medicine, University of California, San Diego, California, USA
- Rady Children’s Hospital, San Diego, California, USA
| | - Hannah C. Carrow
- Department of Pathology, University of California, San Diego, California, USA
| | - William J. Sandborn
- Division of Gastroenterology, University of California, San Diego, California, USA
- Center for Microbiome Innovation, University of California, San Diego, California, USA
| | - Parambir S. Dulai
- Division of Gastroenterology, University of California, San Diego, California, USA
- Division of Gastroenterology, Northwestern University, Chicago, Illinois, USA
| | - Mamata Sivagnanam
- Department of Pediatrics, School of Medicine, University of California, San Diego, California, USA
- Rady Children’s Hospital, San Diego, California, USA
| | - David Pride
- Department of Pathology, University of California, San Diego, California, USA
- Center for Microbiome Innovation, University of California, San Diego, California, USA
- Center for Innovative Phage Applications and Therapeutics (IPATH), University of California, San Diego, California, USA
- Center of Advanced Laboratory Medicine (CALM), University of California, San Diego, California, USA
| | - Rob Knight
- Department of Pediatrics, School of Medicine, University of California, San Diego, California, USA
- Center for Microbiome Innovation, University of California, San Diego, California, USA
- Shu Chien-Gene Lay Department of Bioengineering, University of California, San Diego, California, USA
- Department of Computer Science & Engineering, University of California, San Diego, California, USA
- Halıcıoğlu Data Science Institute, University of California, San Diego, California, USA
| | - Hiutung Chu
- Department of Pathology, University of California, San Diego, California, USA
- Center for Microbiome Innovation, University of California, San Diego, California, USA
- Chiba University-UC San Diego Center for Mucosal Immunology, Allergy and Vaccines (cMAV), University of California, San Diego, California, USA
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2
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Oles RE, Terrazas MC, Loomis LR, Hsu CY, Tribelhorn C, Ferre PB, Ea A, Bryant M, Young J, Carrow HC, Sandborn WJ, Dulai P, Sivagnanam M, Pride D, Knight R, Chu H. Pangenome comparison of Bacteroides fragilis genomospecies unveil genetic diversity and ecological insights. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.20.572674. [PMID: 38187556 PMCID: PMC10769428 DOI: 10.1101/2023.12.20.572674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Bacteroides fragilis is a Gram-negative commensal bacterium commonly found in the human colon that differentiates into two genomospecies termed division I and II. We leverage a comprehensive collection of 694 B. fragilis whole genome sequences and report differential gene abundance to further support the recent proposal that divisions I and II represent separate species. In division I strains, we identify an increased abundance of genes related to complex carbohydrate degradation, colonization, and host niche occupancy, confirming the role of division I strains as gut commensals. In contrast, division II strains display an increased prevalence of plant cell wall degradation genes and exhibit a distinct geographic distribution, primarily originating from Asian countries, suggesting dietary influences. Notably, division II strains have an increased abundance of genes linked to virulence, survival in toxic conditions, and antimicrobial resistance, consistent with a higher incidence of these strains in bloodstream infections. This study provides new evidence supporting a recent proposal for classifying divisions I and II B. fragilis strains as distinct species, and our comparative genomic analysis reveals their niche-specific roles.
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Affiliation(s)
- Renee E Oles
- Department of Pathology, University of California, San Diego, La Jolla, CA
- Department of Pediatrics, School of Medicine, University of California, La Jolla, CA
| | | | - Luke R Loomis
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Chia-Yun Hsu
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Caitlin Tribelhorn
- Department of Pediatrics, School of Medicine, University of California, La Jolla, CA
| | - Pedro Belda Ferre
- Department of Pediatrics, School of Medicine, University of California, La Jolla, CA
| | - Allison Ea
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - MacKenzie Bryant
- Department of Pediatrics, School of Medicine, University of California, La Jolla, CA
| | - Jocelyn Young
- Department of Pediatrics, School of Medicine, University of California, La Jolla, CA
- Rady Children's Hospital, San Diego, CA, United States
| | - Hannah C Carrow
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - William J Sandborn
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
| | - Parambir Dulai
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA
- Division of Gastroenterology, Northwestern University, Chicago, Illinois
| | - Mamata Sivagnanam
- Department of Pediatrics, School of Medicine, University of California, La Jolla, CA
- Rady Children's Hospital, San Diego, CA, United States
| | - David Pride
- Department of Pathology, University of California, San Diego, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
- Center for Innovative Phage Applications and Therapeutics (IPATH), University of California, San Diego, La Jolla, CA
- Center of Advanced Laboratory Medicine (CALM), University of California, San Diego, La Jolla, CA
| | - Rob Knight
- Department of Pediatrics, School of Medicine, University of California, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA
- Department of Computer Science & Engineering, University of California, San Diego, La Jolla, CA
- Halıcıoğlu Data Science Institute, University of California, San Diego, La Jolla, CA
| | - Hiutung Chu
- Department of Pathology, University of California, San Diego, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
- Chiba University-UC San Diego Center for Mucosal Immunology, Allergy and Vaccines (cMAV), University of California, San Diego, La Jolla, CA
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3
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Patrick S. A tale of two habitats: Bacteroides fragilis, a lethal pathogen and resident in the human gastrointestinal microbiome. Microbiology (Reading) 2022; 168. [DOI: 10.1099/mic.0.001156] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Bacteroides fragilis
is an obligately anaerobic Gram-negative bacterium and a major colonizer of the human large colon where
Bacteroides
is a predominant genus. During the growth of an individual clonal population, an astonishing number of reversible DNA inversion events occur, driving within-strain diversity. Additionally, the
B. fragilis
pan-genome contains a large pool of diverse polysaccharide biosynthesis loci, DNA restriction/modification systems and polysaccharide utilization loci, which generates remarkable between-strain diversity. Diversity clearly contributes to the success of
B. fragilis
within its normal habitat of the gastrointestinal (GI) tract and during infection in the extra-intestinal host environment. Within the GI tract,
B. fragilis
is usually symbiotic, for example providing localized nutrients for the gut epithelium, but
B. fragilis
within the GI tract may not always be benign. Metalloprotease toxin production is strongly associated with colorectal cancer.
B. fragilis
is unique amongst bacteria; some strains export a protein >99 % structurally similar to human ubiquitin and antigenically cross-reactive, which suggests a link to autoimmune diseases.
B. fragilis
is not a primary invasive enteric pathogen; however, if colonic contents contaminate the extra-intestinal host environment, it successfully adapts to this new habitat and causes infection; classically peritoneal infection arising from rupture of an inflamed appendix or GI surgery, which if untreated, can progress to bacteraemia and death. In this review selected aspects of
B. fragilis
adaptation to the different habitats of the GI tract and the extra-intestinal host environment are considered, along with the considerable challenges faced when studying this highly variable bacterium.
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Affiliation(s)
- Sheila Patrick
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences Queen’s University Belfast, 97 Lisburn Rd, Belfast BT9 7BL, UK
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Valguarnera E, Wardenburg JB. Good Gone Bad: One Toxin Away From Disease for Bacteroides fragilis. J Mol Biol 2019; 432:765-785. [PMID: 31857085 DOI: 10.1016/j.jmb.2019.12.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 11/27/2019] [Accepted: 12/05/2019] [Indexed: 02/06/2023]
Abstract
The human gut is colonized by hundreds of trillions of microorganisms whose acquisition begins during early infancy. Species from the Bacteroides genus are ubiquitous commensals, comprising about thirty percent of the human gut microbiota. Bacteroides fragilis is one of the least abundant Bacteroides species, yet is the most common anaerobe isolated from extraintestinal infections in humans. A subset of B. fragilis strains carry a genetic element that encodes a metalloprotease enterotoxin named Bacteroides fragilis toxin, or BFT. Toxin-bearing strains, or Enterotoxigenic B. fragilis (ETBF) cause acute and chronic intestinal disease in children and adults. Despite this association with disease, around twenty percent of the human population appear to be asymptomatic carriers of ETBF. BFT damages the colonic epithelial barrier by inducing cleavage of the zonula adherens protein E-cadherin and initiating a cell signaling response characterized by inflammation and c-Myc-dependent pro-oncogenic hyperproliferation. As a consequence, mice harboring genetic mutations that predispose to colonic inflammation or tumor formation are uniquely susceptible to toxin-mediated injury. The recent observation of ETBF-bearing biofilms in colon biopsies from humans with colon cancer susceptibility loci strongly suggests that ETBF is a driver of colorectal cancer. This article will address ETBF biology from a host-pathobiont perspective, including clinical data, analysis of molecular mechanisms of disease, and the complex ecological context of the human gut.
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Affiliation(s)
- Ezequiel Valguarnera
- Department of Pediatrics, Washington University School of Medicine, 660 S. Euclid Ave. Box 8208, St. Louis, MO 63110
| | - Juliane Bubeck Wardenburg
- Department of Pediatrics, Washington University School of Medicine, 660 S. Euclid Ave. Box 8208, St. Louis, MO 63110.
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5
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Desialylation by Edwardsiella tarda is the initial step in the regulation of its invasiveness. Biochem J 2019; 476:3183-3196. [DOI: 10.1042/bcj20190367] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 10/03/2019] [Accepted: 10/14/2019] [Indexed: 01/15/2023]
Abstract
AbstractEdwardsiella tarda is a gram-negative bacterium causing significant economic losses to aquaculture. E. tarda possesses NanA sialidase which removes sialic acids from α2–3 sialo-glycoprotein of host cells. However, the relationship between NanA sialidase activity and E. tarda invasiveness remains poorly understood. Furthermore, the pathway of sialic acid metabolism in E. tarda remains to be elucidated. We studied sialidase activity in several E. tarda strains and found that the pathogenic strains exhibited higher sialidase activity and greater up-regulation of the NanA mRNA level than non-pathogenic strain. Pathogenic strains also showed higher rates of infection in GAKS cells, and the infection was drastically suppressed by sialidase inhibitor. Additionally, NanA gene overexpression significantly increased infection and treatment of E. tarda with free sialic acid enhanced the rate of infection in GAKS cells. Sialic acid treatment enhanced mRNA levels of two N-acetylneuraminate lyases and one N-acetylneuraminate cytidylyltransferase. E. tarda uses sialic acid as a carbon source for growth via N-acetylneuraminate lyases. The strains with high N-acetylneuraminate cytidylyltransferase level showed greater sialylation of the lipopolysaccharides and glycoproteins. Our study establishes the significance of desialylation by E. tarda sialidase in the regulation of its invasiveness.
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6
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Pathogenicity and Virulence of Trueperella pyogenes: A Review. Int J Mol Sci 2019; 20:ijms20112737. [PMID: 31167367 PMCID: PMC6600626 DOI: 10.3390/ijms20112737] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 05/31/2019] [Accepted: 05/31/2019] [Indexed: 12/19/2022] Open
Abstract
Bacteria from the species Trueperella pyogenes are a part of the biota of skin and mucous membranes of the upper respiratory, gastrointestinal, or urogenital tracts of animals, but also, opportunistic pathogens. T. pyogenes causes a variety of purulent infections, such as metritis, mastitis, pneumonia, and abscesses, which, in livestock breeding, generate significant economic losses. Although this species has been known for a long time, many questions concerning the mechanisms of infection pathogenesis, as well as reservoirs and routes of transmission of bacteria, remain poorly understood. Pyolysin is a major known virulence factor of T. pyogenes that belongs to the family of cholesterol-dependent cytolysins. Its cytolytic activity is associated with transmembrane pore formation. Other putative virulence factors, including neuraminidases, extracellular matrix-binding proteins, fimbriae, and biofilm formation ability, contribute to the adhesion and colonization of the host tissues. However, data about the pathogen–host interactions that may be involved in the development of T. pyogenes infection are still limited. The aim of this review is to present the current knowledge about the pathogenic potential and virulence of T. pyogenes.
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7
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Yamamoto T, Ugai H, Nakayama-Imaohji H, Tada A, Elahi M, Houchi H, Kuwahara T. Characterization of a recombinant Bacteroides fragilis sialidase expressed in Escherichia coli. Anaerobe 2018; 50:69-75. [PMID: 29432848 DOI: 10.1016/j.anaerobe.2018.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 01/09/2018] [Accepted: 02/06/2018] [Indexed: 12/17/2022]
Abstract
The human gut commensal Bacteroides fragilis produces sialidases that remove a terminal sialic acid from host-derived polysaccharides. Sialidase is considered to be involved in B. fragilis infection pathology. A native B. fragilis sialidase has been purified and characterized, and was shown to be post-translationally modified by glycosylation. However, the biochemical properties of recombinant B. fragilis sialidase expressed in a heterologous host remain uncharacterized. In this study, we examined the enzymatic properties of the 60-kDa sialidase NanH1 of B. fragilis YCH46, which was prepared as a recombinant protein (rNanH1) in Escherichia coli. In E. coli rNanH1 was expressed as inclusion bodies, which were separated from soluble proteins to allow solubilization of insoluble rNanH1 in a buffer containing 8 M urea and renaturation in refolding buffer containing 100 mM CaCl2 and 50 mM L-arginine. The specific activity of renatured rNanH1 measured using 4-methylumberiferyl-α-D-N-acetyl neuraminic acid as a substrate was 6.16 μmol/min/mg. The optimal pH of rNanH1 ranged from 5.0 to 5.5. The specific activity of rNanH1 was enhanced in the presence of calcium ions. rNanH1 preferentially hydrolyzed the sialyl α2,8 linkage and cleaved sialic acids from mucin and serum proteins (e.g., fetuin and transferrin) but not from α1-acid glycoprotein, which is similar to the previously observed biochemical properties for a native sialidase purified from B. fragilis SBT3182. The results and methods described in this study will be useful for preparing and characterizing recombinant proteins for other B. fragilis sialidase isoenzymes.
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Affiliation(s)
- Takaaki Yamamoto
- Department of Pharmacy, Kagawa University Hospital, 1750-1 Miki, Kagawa, 761-0793, Japan
| | - Hideyo Ugai
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750-1 Miki, Kagawa, 761-0793, Japan
| | - Haruyuki Nakayama-Imaohji
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750-1 Miki, Kagawa, 761-0793, Japan
| | - Ayano Tada
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750-1 Miki, Kagawa, 761-0793, Japan
| | - Miad Elahi
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750-1 Miki, Kagawa, 761-0793, Japan
| | - Hitoshi Houchi
- Department of Pharmacy, Kagawa University Hospital, 1750-1 Miki, Kagawa, 761-0793, Japan
| | - Tomomi Kuwahara
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750-1 Miki, Kagawa, 761-0793, Japan.
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8
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Abstract
Sialidases are a large group of enzymes, the majority of which catalyses the cleavage of terminal sialic acids from complex carbohydrates on glycoproteins or glycolipids. In the gastrointestinal (GI) tract, sialic acid residues are mostly found in terminal location of mucins via α2-3/6 glycosidic linkages. Many enteric commensal and pathogenic bacteria can utilize sialic acids as a nutrient source, but not all express the sialidases that are required to release free sialic acid. Sialidases encoded by gut bacteria vary in terms of their substrate specificity and their enzymatic reaction. Most are hydrolytic sialidases, which release free sialic acid from sialylated substrates. However, there are also examples with transglycosylation activities. Recently, a third class of sialidases, intramolecular trans-sialidase (IT-sialidase), has been discovered in gut microbiota, releasing (2,7-anhydro-Neu5Ac) 2,7-anydro-N-acetylneuraminic acid instead of sialic acid. Reaction specificity varies, with hydrolytic sialidases demonstrating broad activity against α2,3-, α2,6- and α2,8-linked substrates, whereas IT-sialidases tend to be specific for α2,3-linked substrates. In this mini-review, we summarize the current knowledge on the structural and biochemical properties of sialidases involved in the interaction between gut bacteria and epithelial surfaces.
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9
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Efficient utilization of complex N-linked glycans is a selective advantage for Bacteroides fragilis in extraintestinal infections. Proc Natl Acad Sci U S A 2014; 111:12901-6. [PMID: 25139987 DOI: 10.1073/pnas.1407344111] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Bacteroides fragilis is the most common anaerobe isolated from clinical infections, and in this report we demonstrate a characteristic of the species that is critical to their success as an opportunistic pathogen. Among the Bacteroides spp. in the gut, B. fragilis has the unique ability of efficiently harvesting complex N-linked glycans from the glycoproteins common to serum and serous fluid. This activity is mediated by an outer membrane protein complex designated as Don. Using the abundant serum glycoprotein transferrin as a model, it has been shown that B. fragilis alone can rapidly and efficiently deglycosylate this protein in vitro and that transferrin glycans can provide the sole source of carbon and energy for growth in defined media. We then showed that transferrin deglycosylation occurs in vivo when B. fragilis is propagated in the rat tissue cage model of extraintestinal growth, and that this ability provides a competitive advantage in vivo over strains lacking the don locus.
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10
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Unified theory of bacterial sialometabolism: how and why bacteria metabolize host sialic acids. ISRN MICROBIOLOGY 2013; 2013:816713. [PMID: 23724337 PMCID: PMC3658417 DOI: 10.1155/2013/816713] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 09/27/2012] [Indexed: 11/18/2022]
Abstract
Sialic acids are structurally diverse nine-carbon ketosugars found mostly in humans and other animals as the terminal units on carbohydrate chains linked to proteins or lipids. The sialic acids function in cell-cell and cell-molecule interactions necessary for organismic development and homeostasis. They not only pose a barrier to microorganisms inhabiting or invading an animal mucosal surface, but also present a source of potential carbon, nitrogen, and cell wall metabolites necessary for bacterial colonization, persistence, growth, and, occasionally, disease. The explosion of microbial genomic sequencing projects reveals remarkable diversity in bacterial sialic acid metabolic potential. How bacteria exploit host sialic acids includes a surprisingly complex array of metabolic and regulatory capabilities that is just now entering a mature research stage. This paper attempts to describe the variety of bacterial sialometabolic systems by focusing on recent advances at the molecular and host-microbe-interaction levels. The hope is that this focus will provide a framework for further research that holds promise for better understanding of the metabolic interplay between bacterial growth and the host environment. An ability to modify or block this interplay has already yielded important new insights into potentially new therapeutic approaches for modifying or blocking bacterial colonization or infection.
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11
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Nakayama-Imaohji H, Ichimura M, Iwasa T, Okada N, Ohnishi Y, Kuwahara T. Characterization of a gene cluster for sialoglycoconjugate utilization in Bacteroides fragilis. THE JOURNAL OF MEDICAL INVESTIGATION 2012; 59:79-94. [PMID: 22449996 DOI: 10.2152/jmi.59.79] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Recent analysis of the whole genome sequence of Bacteroides fragilis revealed extensive duplication of polysaccharide utilization genes in this anaerobe. Here we analyzed a unique 27-kb gene cluster (sgu) comprised of the 13 sialoglycoconjugates-utilization genes, which include the sialidase gene (nanH1) in B. fragilis strain YCH46. The genes were tightly organized and transcribed polycistronically. Comparative PCR scanning demonstrated that the sgu locus was conserved among the Bacteroides strains tested. Based on the transcriptional profiles generated by reverse transcriptase PCR, the sgu locus can be classified into at least three regulatory units: 1) sialic acid- or sialooligosaccharide-inducible genes, 2) constitutively expressed genes that can be down-regulated by catabolite repression, and 3) constitutively expressed genes. In vitro comparison of the growth of a sgu locus deletion mutant (SGUM172941) with a wild type strain indicates that this locus is necessary for B. fragilis to efficiently utilize mucin as a carbon source. Furthermore, SGUM172941 was defective in colonization of the intestines of germ-free mice under competitive conditions. These data indicate that the sgu locus in B. fragilis plays a crucial role in the utilization of host-derived sialoglycoconjugates and the stable colonization of this anaerobe in the human gut.
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Affiliation(s)
- Haruyuki Nakayama-Imaohji
- Department of Immunology and Parasitology, Institute of Health Biosciences, the University of Tokushima Graduate School, Tokushima, Japan
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12
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Park CW, Kang IC, Choi Y. Activity-based screening system for the discovery of neuraminidase inhibitors using protein chip technology. BIOCHIP JOURNAL 2012. [DOI: 10.1007/s13206-012-6205-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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13
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Lewis AL, Lewis WG. Host sialoglycans and bacterial sialidases: a mucosal perspective. Cell Microbiol 2012; 14:1174-82. [PMID: 22519819 DOI: 10.1111/j.1462-5822.2012.01807.x] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 04/09/2012] [Accepted: 04/17/2012] [Indexed: 12/20/2022]
Abstract
Sialic acids are nine-carbon-backbone sugars that occupy outermost positions on vertebrate cells and secreted sialoglycoproteins. These negatively charged hydrophilic carbohydrates have a variety of biological, biophysical and immunological functions. Mucosal surfaces and secretions of the mouth, airway, gut and vagina are especially sialoglycan-rich. Given their prominent positions and important functions, a variety of microbial strategies have targeted host sialic acids for adherence, mimicry and/or degradation. Here we review the roles of bacterial sialidases (neuraminidases) during colonization and pathogenesis of mammalian mucosal surfaces. Evidence is presented to support the myriad roles of mucosal sialoglycans in protecting the host from bacterial infection. In opposition, many bacteria hydrolyse sialic acids during associations with the gastrointestinal, oral, respiratory and reproductive tracts. Sialidases promote bacterial survival in mucosal niche environments in several ways, including: (i) nutritional benefits of sialic acid catabolism, (ii) unmasking of cryptic host ligands used for adherence, (iii) participation in biofilm formation and (iv) modulation of immune function. Bacterial sialidases are among the best-studied enzymes involved in pathogenesis and may also drive commensal and/or symbiotic host associations. Future studies should continue to define host substrates of bacterial sialidases and the mechanisms of their pathologic, commensal and symbiotic interactions with the mammalian host.
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Affiliation(s)
- Amanda L Lewis
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA.
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14
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Stafford G, Roy S, Honma K, Sharma A. Sialic acid, periodontal pathogens and Tannerella forsythia: stick around and enjoy the feast! Mol Oral Microbiol 2012; 27:11-22. [PMID: 22230462 PMCID: PMC4049603 DOI: 10.1111/j.2041-1014.2011.00630.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Periodontal pathogens, like any other human commensal or pathogenic bacterium, must possess both the ability to acquire the necessary growth factors and the means to adhere to surfaces or reside and survive in their environmental niche. Recent evidence has suggested that sialic acid containing host molecules may provide both of these requirements in vivo for several periodontal pathogens but most notably for the red complex organism Tannerella forsythia. Several other periodontal pathogens also possess sialic acid scavenging enzymes - sialidases, which can also expose adhesive epitopes, but might also act as adhesins in their own right. In addition, recent experimental work coupled with the release of several genome sequences has revealed that periodontal bacteria have a range of sialic acid uptake and utilization systems while others may also use sialic acid as a cloaking device on their surface to mimic host and avoid immune recognition. This review will focus on these systems in a range of periodontal bacteria with a focus on Ta. forsythia.
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Affiliation(s)
- G Stafford
- Oral and Maxillofacial Pathology, School of Clinical Dentistry, University of Sheffield, Sheffield, UK.
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15
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Meehan BM, Malamy MH. Fumarate reductase is a major contributor to the generation of reactive oxygen species in the anaerobe Bacteroides fragilis. MICROBIOLOGY-SGM 2011; 158:539-546. [PMID: 22075026 DOI: 10.1099/mic.0.054403-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Despite the detrimental role that endogenously generated reactive oxygen species (ROS) may play in bacteria exposed to aerobic environments, very few sources of ROS have been identified in vivo. Such studies are often precluded by the presence of efficient ROS-scavenging pathways, like those found in the aerotolerant anaerobe Bacteroides fragilis. Here we demonstrate that deletion of the genes encoding catalase (Kat), alkylhydroperoxide reductase (AhpC) and thioredoxin-dependent peroxidase (Tpx) strongly inhibits H(2)O(2) detoxification in B. fragilis, thereby allowing for the quantification of ROS production. Exogenous fumarate significantly reduced H(2)O(2) production in a ΔahpCΔkatΔtpx B. fragilis strain, as did deletion of fumarate reductase subunit c (frdC). Deletion of frdC also increased the aerotolerance of a strain lacking superoxide dismutase, indicating that fumarate reductase is a major contributor to ROS formation in B. fragilis exposed to oxygen.
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Affiliation(s)
- Brian M Meehan
- Department of Molecular Biology and Microbiology, Tufts University Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA
| | - Michael H Malamy
- Department of Molecular Biology and Microbiology, Tufts University Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA
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16
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Almagro-Moreno S, Boyd EF. Bacterial catabolism of nonulosonic (sialic) acid and fitness in the gut. Gut Microbes 2010; 1:45-50. [PMID: 21327116 PMCID: PMC3035139 DOI: 10.4161/gmic.1.1.10386] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 10/22/2009] [Indexed: 02/03/2023] Open
Abstract
The term nonulosonic acid or sialic acid encompasses a varied group of nine-carbon amino sugars widely distributed among mammals and higher metazoans. Among bacteria, the ability to synthesize sialic acid was first examined in a small number of human pathogenic species that deposit sialic acid on their outer surface. New phylogenomic data suggest that the ability to synthesize sialic acid and sialic acid-like compounds is not a novel bacterial innovation but a much more widespread ancient trait. In contrast, the genes required for the catabolism of sialic acid are found only among pathogenic and commensal bacterial species. This ability to utilize sialic acid as a carbon source is correlated with bacterial virulence, especially, in the sialic acid rich environment of the gut. In this article, we present the most recent findings in sialobiology with a focus on sialic acid catabolism.
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Macfarlane, M. J. Hopkins, G. T. Ma S. Bacterial Growth and Metabolism on Surfaces in the Large Intestine. MICROBIAL ECOLOGY IN HEALTH AND DISEASE 2009. [DOI: 10.1080/089106000750060314] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Sialic acid (N-acetyl neuraminic acid) utilization by Bacteroides fragilis requires a novel N-acetyl mannosamine epimerase. J Bacteriol 2009; 191:3629-38. [PMID: 19304853 DOI: 10.1128/jb.00811-08] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We characterized the nanLET operon in Bacteroides fragilis, whose products are required for the utilization of the sialic acid N-acetyl neuraminic acid (NANA) as a carbon and energy source. The first gene of the operon is nanL, which codes for an aldolase that cleaves NANA into N-acetyl mannosamine (manNAc) and pyruvate. The next gene, nanE, codes for a manNAc/N-acetylglucosamine (NAG) epimerase, which, intriguingly, possesses more similarity to eukaryotic renin binding proteins than to other bacterial NanE epimerase proteins. Unphosphorylated manNAc is the substrate of NanE, while ATP is a cofactor in the epimerase reaction. The third gene of the operon is nanT, which shows similarity to the major transporter facilitator superfamily and is most likely to be a NANA transporter. Deletion of any of these genes eliminates the ability of B. fragilis to grow on NANA. Although B. fragilis does not normally grow with manNAc as the sole carbon source, we isolated a B. fragilis mutant strain that can grow on this substrate, likely due to a mutation in a NAG transporter; both manNAc transport and NAG transport are affected in this strain. Deletion of the nanE epimerase gene or the rokA hexokinase gene, whose product phosphorylates NAG, in the manNAc-enabled strain abolishes growth on manNAc. Thus, B. fragilis possesses a new pathway of NANA utilization, which we show is also found in other Bacteroides species.
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An orthologue of Bacteroides fragilis NanH is the principal sialidase in Tannerella forsythia. J Bacteriol 2009; 191:3623-8. [PMID: 19304852 DOI: 10.1128/jb.01618-08] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sialidase activity is a putative virulence factor of the anaerobic periodontal pathogen Tannerella forsythia, but it is uncertain which genes encode this activity. Characterization of a putative sialidase, SiaHI, by others, indicated that this protein alone may not be responsible for all of the sialidase activity. We describe a second sialidase in T. forsythia (TF0035), an orthologue of Bacteroides fragilis NanH, and its expression in Escherichia coli. Sialidase activity of the expressed NanH was confirmed by using 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid as a substrate. Biochemical characterization of the recombinant T. forsythia NanH indicated that it was active over a broad pH range, with optimum activity at pH 5.5. This enzyme has high affinity for 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid (K(m) of 32.9 +/- 10.3 microM) and rapidly releases 4-methylumbelliferone (V(max) of 170.8 +/- 11.8 nmol of 4-methylumbelliferone min(-1) mg of protein(-1)). E. coli lysates containing recombinant T. forsythia NanH cleave sialic acid from a range of substrates, with a preference for alpha2-3 glycosidic linkages. The genes adjacent to nanH encode proteins apparently involved in the metabolism of sialic acid, indicating that the NanH sialidase is likely to be involved in nutrient acquisition.
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20
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Sund CJ, Rocha ER, Tzianabos AO, Tzinabos AO, Wells WG, Gee JM, Reott MA, O'Rourke DP, Smith CJ. The Bacteroides fragilis transcriptome response to oxygen and H2O2: the role of OxyR and its effect on survival and virulence. Mol Microbiol 2007; 67:129-42. [PMID: 18047569 DOI: 10.1111/j.1365-2958.2007.06031.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intestinal anaerobic symbiont, Bacteroides fragilis, is highly aerotolerant and resistant to H(2)O(2). Analysis of the transcriptome showed that expression of 45% of the genome was significantly affected by oxidative stress. The gene expression patterns suggested that exposure to oxidative stress induced an acute response to rapidly minimize the immediate effects of reactive oxygen species, then upon extended exposure a broad metabolic response was induced. This metabolic response induced genes encoding enzymes that can supply reducing power for detoxification and restore energy-generating capacity. An integral aspect of the metabolic response was downregulation of genes related to translation and biosynthesis which correlated with decreased growth and entry into a stationary phase-like growth state. Examination of oxyR mutants showed that they were impaired for the acute response and they induced the expanded metabolic response with only minimal exposure to stress. The oxyR mutants were more sensitive to oxidants in vitro and in vivo they were attenuated in an intra-abdominal abscess infection model. Aerotolerance and resistance to oxidative stress are physiological adaptations of B. fragilis to its environment that enhance survival in extra-intestinal sites and promote opportunistic infections.
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Affiliation(s)
- Christian J Sund
- Department of Microbiology and Immunology, East Carolina University, Brody School of Medicine, Greenville, NC 27834, USA
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Abstract
SUMMARY Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin).
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Pumbwe L, Skilbeck CA, Wexler HM. The Bacteroides fragilis cell envelope: quarterback, linebacker, coach-or all three? Anaerobe 2006; 12:211-20. [PMID: 17045496 DOI: 10.1016/j.anaerobe.2006.09.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2006] [Accepted: 09/18/2006] [Indexed: 11/27/2022]
Abstract
Bacteroides fragilis is an anaerobic commensal constituting only 1-2% of the micro-flora of the human gastrointestinal tract, yet it is the predominant anaerobic isolate in cases of intraabdominal sepsis and bacteremia. B. fragilis can play two roles in the host: in its role as friendly commensal, it must be able to establish itself in the host intestinal mucosa, to utilize and process polysaccharides for use by the host, and to resist the noxious effects of bile salts. In its role as pathogen, it must be able to attach itself to the site of infection, evade killing mechanisms by host defense, withstand antimicrobial treatment and produce factors that damage host tissue. The cell envelope of B. fragilis, likewise, must be able to function in the roles of aggressor, defender and strategist in allowing the organism to establish itself in the host--whether as friend or foe. Recent studies of the genomes and proteomes of the genus Bacteroides suggest that these organisms have evolved strategies to survive and dominate in the overcrowded gastrointestinal neighborhood. Analysis of the proteomes of B. fragilis and Bacteroides thetaiotaomicron demonstrates both a tremendous capacity to use a wide range of dietary polysaccharides, and the capacity to create variable surface antigenicities by multiple DNA inversion systems. The latter characteristic is particularly pronounced in the species B. fragilis, which is more frequently found at the mucosal surface (i.e., often the site of attack by host defenses). The B. fragilis cell envelope undergoes major protein expression and ultrastructural changes in response to stressors such as bile or antimicrobial agents. These agents may also act as signals for attachment and colonization. Thus the bacterium manages its surface characteristics to enable it to bind to its target, to use the available nutrients, and to avoid or evade hostile forces (host-derived or external) in its multiple roles.
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Affiliation(s)
- Lilian Pumbwe
- Greater Los Angeles Veterans Administration Healthcare Systems and Department of Medicine, University of California, Los Angeles, CA 90073, USA
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23
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Soong G, Muir A, Gomez MI, Waks J, Reddy B, Planet P, Singh PK, Kanetko Y, Wolfgang MC, Hsiao YS, Tong L, Prince A. Bacterial neuraminidase facilitates mucosal infection by participating in biofilm production. J Clin Invest 2006; 116:2297-2305. [PMID: 16862214 PMCID: PMC1513050 DOI: 10.1172/jci27920] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Accepted: 05/23/2006] [Indexed: 01/10/2023] Open
Abstract
Many respiratory pathogens, including Hemophilus influenzae, Streptococcus pneumoniae, and Pseudomonas aeruginosa, express neuraminidases that can cleave alpha2,3-linked sialic acids from glycoconjugates. As mucosal surfaces are heavily sialylated, neuraminidases have been thought to modify epithelial cells by exposing potential bacterial receptors. However, in contrast to neuraminidase produced by the influenza virus, a role for bacterial neuraminidase in pathogenesis has not yet been clearly established. We constructed a mutant of P. aeruginosa PAO1 by deleting the PA2794 neuraminidase locus (Delta2794) and tested its virulence and immunostimulatory capabilities in a mouse model of infection. Although fully virulent when introduced i.p., the Delta2794 mutant was unable to establish respiratory infection by i.n. inoculation. The inability to colonize the respiratory tract correlated with diminished production of biofilm, as assessed by scanning electron microscopy and in vitro assays. The importance of neuraminidase in biofilm production was further demonstrated by showing that viral neuraminidase inhibitors in clinical use blocked P. aeruginosa biofilm production in vitro as well. The P. aeruginosa neuraminidase has a key role in the initial stages of pulmonary infection by targeting bacterial glycoconjugates and contributing to the formation of biofilm. Inhibiting bacterial neuraminidases could provide a novel mechanism to prevent bacterial pneumonia.
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Affiliation(s)
- Grace Soong
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Amanda Muir
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Marisa I. Gomez
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Jonathan Waks
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Bharat Reddy
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Paul Planet
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Pradeep K. Singh
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Yukihiro Kanetko
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Matthew C. Wolfgang
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Yu-Shan Hsiao
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Liang Tong
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Alice Prince
- Departments of Pediatrics and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Cystic Fibrosis Pulmonary Research and Treatment Center, Chapel Hill, North Carolina, USA.
Department of Biological Sciences, Columbia University, New York, New York, USA
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Spence C, Wells WG, Smith CJ. Characterization of the primary starch utilization operon in the obligate anaerobe Bacteroides fragilis: Regulation by carbon source and oxygen. J Bacteriol 2006; 188:4663-72. [PMID: 16788175 PMCID: PMC1482989 DOI: 10.1128/jb.00125-06] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The opportunistic pathogen Bacteroides fragilis is a commensal organism in the large intestine, where it utilizes both dietary and host-derived polysaccharides as a source of carbon and energy. In this study, a four-gene operon required for starch utilization was identified. The operon also was found to be oxygen responsive and thus was designated osu for oxygen-induced starch utilization. The first three genes in the operon were predicted to encode outer membrane proteins involved in starch binding, and a fourth gene, osuD, encoded an amylase involved in starch hydrolysis. Insertional mutation of the osuA gene (Omega osuA) resulted in the inability to utilize starch or glycogen and an insertional mutation into the osuD gene (Omega osuD) was severely impaired for growth on starch media. Transcriptional studies indicated that maltose, maltooligosaccharides, and starch were inducers of osu expression and that maltose was the strongest inducer. A transcriptional activator of osuABCD, OsuR, was identified and found to mediate maltose induction. The Omega osuA and Omega osuD mutants were able to grow on maltose but not starch, whereas a mutation in osuR abolished growth on both substrates, indicating that additional genes under the control of OsuR are needed for maltose utilization. The osuABCD operon also was induced by exposure to oxygen and was shown to be part of the oxidative stress response important for aerotolerance of B. fragilis. Transcriptional analyses showed that osuA was induced 20-fold by oxygen, but OsuR was not required for this activation. Analysis of osu mutants suggested that expression of the operon was important for survival during oxygen exposure but not to hydrogen peroxide stress.
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Affiliation(s)
- Cheryl Spence
- Dept. of Microbiology and Immunology, Brody School of Medicine, 600 Moye Blvd., East Carolina University, Greenville, NC 27834, USA
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25
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Sund CJ, Greg Wells W, Jeffrey Smith C. TheBacteroides fragilisP20 scavengase homolog is important in the oxidative stress response but is not controlled by OxyR. FEMS Microbiol Lett 2006; 261:211-7. [PMID: 16907722 DOI: 10.1111/j.1574-6968.2006.00353.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The oxidative stress response of obligate anaerobe, Bacteroides fragilis, is partially controlled by the redox regulator OxyR but an oxyR null mutant maintains a high level of aerotolerance. Studies using two-dimensional polyacrylamide gel electrophoresis showed that a thiol peroxidase-scavengase, Tps, was induced during oxygen exposure of an oxyR mutant. Tps is similar to 'atypical 2-cysteine peroxidases' such as scavengase p20 and it demonstrated catalytic activity against t-butyl hydroperoxide and H(2)O(2). A second gene, oim, encoding a putative membrane protein, was divergently transcribed from tps. Transcriptional analysis indicated that tps and oim were coordinately regulated by oxygen induction via an OxyR-independent mechanism. H(2)O(2) was a less potent inducer than oxygen exposure and in an oxyR mutant the mRNA levels were slightly reduced compared with the wild type. A null mutant of tps had increased sensitivity to killing by t-butyl hydroperoxide and oxygen but an oim mutant was similar to wild type. These data indicate that Tps is important for protection against some forms of oxidative stress.
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Affiliation(s)
- Christian J Sund
- Department of Microbiology & Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
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26
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Brigham CJ, Malamy MH. Characterization of the RokA and HexA broad-substrate-specificity hexokinases from Bacteroides fragilis and their role in hexose and N-acetylglucosamine utilization. J Bacteriol 2005; 187:890-901. [PMID: 15659667 PMCID: PMC545704 DOI: 10.1128/jb.187.3.890-901.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteroides fragilis, a human gastrointestinal commensal and an opportunistic pathogen, utilizes simple and complex sugars and polysaccharides for growth in the large intestine and at sites of infection. Because B. fragilis lacks transport-linked sugar phosphorylation systems, cytoplasmic kinase(s) was expected to be required for the phosphorylation of hexoses and hexosamines. We have now identified two hexose kinases that are important for growth of B. fragilis on glucose, mannose, and other sugars. One kinase (RokA), a member of the ROK family of proteins, was found to be the sole kinase for activation of N-acetyl-D-glucosamine (NAG). The other kinase (HexA) is responsible for the majority of the glucose kinase activity in the cell, although a hexA deletion mutant strain was not defective for growth on any substrate tested. Deletion of both the rokA and hexA kinase genes resulted in inability of the cell to use glucose, mannose, NAG, and many other sugars. We purified RokA and determined its approximate molecular mass to be 36.5 kDa. The purified RokA protein was shown to phosphorylate several substrates, including glucose, NAG, and mannose, but not N-acetylmannosamine or N-acetylneuraminic acid. Phylogenetic analysis of RokA showed that it is most similar to kinases from the Cytophaga-Flavibacterium-Bacteroides group, while HexA was most similar to other bacterial hexokinases and eukaryotic hexokinases.
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Affiliation(s)
- Christopher J Brigham
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111.
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27
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Henderson IR, Navarro-Garcia F, Desvaux M, Fernandez RC, Ala'Aldeen D. Type V protein secretion pathway: the autotransporter story. Microbiol Mol Biol Rev 2004; 68:692-744. [PMID: 15590781 PMCID: PMC539010 DOI: 10.1128/mmbr.68.4.692-744.2004] [Citation(s) in RCA: 595] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Gram-negative bacteria possess an outer membrane layer which constrains uptake and secretion of solutes and polypeptides. To overcome this barrier, bacteria have developed several systems for protein secretion. The type V secretion pathway encompasses the autotransporter proteins, the two-partner secretion system, and the recently described type Vc or AT-2 family of proteins. Since its discovery in the late 1980s, this family of secreted proteins has expanded continuously, due largely to the advent of the genomic age, to become the largest group of secreted proteins in gram-negative bacteria. Several of these proteins play essential roles in the pathogenesis of bacterial infections and have been characterized in detail, demonstrating a diverse array of function including the ability to condense host cell actin and to modulate apoptosis. However, most of the autotransporter proteins remain to be characterized. In light of new discoveries and controversies in this research field, this review considers the autotransporter secretion process in the context of the more general field of bacterial protein translocation and exoprotein function.
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Affiliation(s)
- Ian R Henderson
- Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, UK.
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28
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Vimr ER, Kalivoda KA, Deszo EL, Steenbergen SM. Diversity of microbial sialic acid metabolism. Microbiol Mol Biol Rev 2004; 68:132-53. [PMID: 15007099 PMCID: PMC362108 DOI: 10.1128/mmbr.68.1.132-153.2004] [Citation(s) in RCA: 445] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sialic acids are structurally unique nine-carbon keto sugars occupying the interface between the host and commensal or pathogenic microorganisms. An important function of host sialic acid is to regulate innate immunity, and microbes have evolved various strategies for subverting this process by decorating their surfaces with sialylated oligosaccharides that mimic those of the host. These subversive strategies include a de novo synthetic pathway and at least two truncated pathways that depend on scavenging host-derived intermediates. A fourth strategy involves modification of sialidases so that instead of transferring sialic acid to water (hydrolysis), a second active site is created for binding alternative acceptors. Sialic acids also are excellent sources of carbon, nitrogen, energy, and precursors of cell wall biosynthesis. The catabolic strategies for exploiting host sialic acids as nutritional sources are as diverse as the biosynthetic mechanisms, including examples of horizontal gene transfer and multiple transport systems. Finally, as compounds coating the surfaces of virtually every vertebrate cell, sialic acids provide information about the host environment that, at least in Escherichia coli, is interpreted by the global regulator encoded by nanR. In addition to regulating the catabolism of sialic acids through the nan operon, NanR controls at least two other operons of unknown function and appears to participate in the regulation of type 1 fimbrial phase variation. Sialic acid is, therefore, a host molecule to be copied (molecular mimicry), eaten (nutrition), and interpreted (cell signaling) by diverse metabolic machinery in all major groups of mammalian pathogens and commensals.
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Affiliation(s)
- Eric R Vimr
- Laboratory of Sialobiology and Microbial Metabolomics, Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA.
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29
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Ringenberg MA, Steenbergen SM, Vimr ER. The first committed step in the biosynthesis of sialic acid by Escherichia coli K1 does not involve a phosphorylated N-acetylmannosamine intermediate. Mol Microbiol 2004; 50:961-75. [PMID: 14617154 DOI: 10.1046/j.1365-2958.2003.03741.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A variety of pathogens or commensals use at least one of four distinct mechanisms for decorating their surfaces with sialic acid as a strategy to avoid, subvert or inhibit host innate immunity. The metabolism of sialic acid thus is central to a range of host-pathogen interactions. The first committed step in this process, the production of free N-acetylmannosamine (ManNAc), has not been defined. Here we show that ManNAc-6-phosphate (ManNAc-6-P) is not an obligate sialate precursor in Escherichia coli K1. This conclusion was supported by 31P NMR spectroscopy of E. coli K1 derivatives engineered with different combinations of mutations in nanA (sialate aldolase or lyase), nanK (ManNAc kinase), nanE (ManNAc-6-P 2-epimerase), neuS (polysialyltransferase) and neuB (sialate synthase). The product specificities for purified NanK and NanE were determined by chromatographic analyses. Direct biochemical analysis showed that ManNAc-6-P was stable in a nanE mutant extract. The combined results indicate that neither ManNAc-6-P nor specific or non-specific phosphatase are necessary to generate the requisite ManNAc for sialate biosynthesis. Our results imply that the neuC gene product encodes an UDP-N-acetylglucosamine 2-epimerase that generates ManNAc directly from the dinucleotide-sugar precursor despite detection of only this enzyme's UDP-GlcNAc hydrolase activity. This study describes the first use of NMR for analysing intermediate flux within the sialate biosynthetic pathway.
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Affiliation(s)
- Michael A Ringenberg
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
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Rocha ER, Herren CD, Smalley DJ, Smith CJ. The complex oxidative stress response of Bacteroides fragilis: the role of OxyR in control of gene expression. Anaerobe 2003; 9:165-73. [PMID: 16887706 DOI: 10.1016/s1075-9964(03)00118-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2002] [Accepted: 07/09/2003] [Indexed: 11/28/2022]
Abstract
Gram-negative anaerobes in the genus Bacteroides are the predominant members of the GI-tract microflora where they play an important role in normal intestinal physiology. Bacteroides spp. also are significant opportunistic pathogens responsible for an array of intra-abdominal and other infections. Bacteroides fragilis is the most common anaerobic pathogen and it possesses virulence factors such as a capsule and neuraminidase that contribute to its success as a pathogen. Infection occurs when organisms escape from the anaerobic colon to aerobic sites such as the peritoneum where O(2) concentrations average 6%. Thus in addition to the classic virulence factors, resistance to oxidative stress is essential and may be involved in the initiation and persistence of infection. In fact, B. fragilis is highly O(2) tolerant, surviving extended periods (>24h) of O(2) exposure without a significant affect on viability. For protection against this oxidative stress B. fragilis mounts a complex physiological response that includes induction of >28 proteins involved in detoxification of oxygen radicals, protection of macromolecules, and adaptive physiology. One experimental strategy used to characterize this oxidative stress response is the direct detection of genes and proteins induced during exposure to O(2) or H(2)O(2). The methods employed have included RNA differential display to capture unique mRNA transcripts produced during oxidative stress, and native or 2D-gel electrophoresis to isolate and identify newly formed stress-induced proteins. Using these and other approaches a wide array of genes induced by oxidative stress have been discovered. These include genes for catalase, superoxide dismutase, thioredoxin-peroxidase, p20-peroxidase, cytochrome c peroxidase, Dps, alkyl hydroperoxidase, aerobic ribonucleotide reductase, ruberythrin, starch utilization, aspartate decarboxylase, and an RNA binding protein. The genes encoding these activities fall into three regulatory classes: (1) induced by O(2) only, (2) induced by H(2)O(2) only, and (3) induced by either O(2) or H(2)O(2). Such a complex regulatory response will likely involve multiple regulators. Thus far one regulator has been identified, OxyR, which controls a subset of the class 3 genes that are induced by either O(2) or H(2)O(2). OxyR responds rapidly to oxidative stress and transcriptional analyses have shown that OxyR-controlled genes are activated by as little as 0.5% O(2) or 10 microM H(2)O(2). Maximal expression of most OxyR regulon genes was reached at 50 microM H(2)O(2) and 2% O(2). These oxidant concentrations are similar to environmental levels that would be experienced by the organisms in tissues outside of the colon suggesting that the OxyR regulon would be induced during the course of an infection.
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Affiliation(s)
- E R Rocha
- Department of Microbiology and Immunology, East Carolina University, 600 Moye Blvd., Greenville, NC 27858-4354, USA
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31
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Lichtensteiger CA, Vimr ER. Purification and renaturation of membrane neuraminidase from Haemophilus parasuis. Vet Microbiol 2003; 93:79-87. [PMID: 12591209 DOI: 10.1016/s0378-1135(02)00443-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Haemophilus parasuis, which causes polyserositis, polysynovitis, meningitis, septicemia, and pneumonia in pigs, has emerged as an increasing problem in modern swine production systems. Co-factors for and the pathogenesis of H. parasuis disease are not defined. One of the potential virulence factors of H. parasuis is its neuraminidase (sialidase). While purifying the H. parasuis neuraminidase from the membrane fraction, we developed a protocol to renature enzymatic activity after enzyme preparations were resolved electrophorectically in denaturing polyacrylamide gels. The H. parasuis neuraminidase co-resolved with recombinant neuraminidase of Vibrio cholera; thus its apparent molecular mass is 82 kilodalton (kDa). The H. parasuis neuraminidase was associated with the membrane fraction and the purification protocol removed over 99% of the H. parasuis cell protein while retaining over 90% of the neuraminidase activity. Purified protein will provide another avenue to clone the neuraminidase gene that has been refractory to cloning and the protocol will be a means to purify recombinant protein.
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Affiliation(s)
- Carol A Lichtensteiger
- Department of Pathobiology, Veterinary Diagnostic Laboratory, University of Illinois Urbana-Champaign Campus, 2001 South Lincoln Avenue, Urbana, IL 61802, USA.
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Smalley D, Rocha ER, Smith CJ. Aerobic-type ribonucleotide reductase in the anaerobe Bacteroides fragilis. J Bacteriol 2002; 184:895-903. [PMID: 11807048 PMCID: PMC134816 DOI: 10.1128/jb.184.4.895-903.2002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteroides fragilis, a component of the normal intestinal flora, is an obligate anaerobe capable of long-term survival in the presence of air. Survival is attributed to an elaborate oxidative stress response that controls the induction of more than 28 peptides, but there is limited knowledge concerning the identities of these peptides. In this report, RNA fingerprinting by arbitrarily primed PCR identified five new genes whose expression increased following exposure to O2. Nucleotide sequence analysis of the cloned genes indicated that they encoded an outer membrane protein, an aspartate decarboxylase, an efflux pump, heat shock protein HtpG, and an NrdA ortholog constituting the large subunit of a class Ia ribonucleotide reductase (RRase). Attention was focused on the nrdA gene since class I RRases are obligate aerobic enzymes catalyzing the reduction of ribonucleoside 5'-diphosphates by a mechanism that requires molecular oxygen for activity. Sequence analysis of the nrd locus showed that two genes, nrdA and nrdB, are located in the same orientation in a 4.5-kb region. Northern hybridization and primer extension experiments confirmed induction of the genes by O2 and suggested they are an operon. The B. fragilis nrdA and nrdB genes were overexpressed in Escherichia coli, and CDP reductase assays confirmed that they encoded an active enzyme. The enzyme activity was inhibited by hydroxyurea, and ATP was shown to be a positive effector of CDP reductase activity, while dATP was an inhibitor, indicating that the enzyme was a class Ia RRase. A nrdA mutant was viable under anaerobic conditions but had decreased survival following exposure to O2, and it could not rapidly resume growth after O2 treatment. The results presented indicate that during aerobic conditions B. fragilis NrdAB may have a role in maintaining deoxyribonucleotide pools for DNA repair and growth recovery.
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Affiliation(s)
- Darren Smalley
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina 27858-4354, USA
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Wiggins R, Hicks SJ, Soothill PW, Millar MR, Corfield AP. Mucinases and sialidases: their role in the pathogenesis of sexually transmitted infections in the female genital tract. Sex Transm Infect 2001; 77:402-8. [PMID: 11714935 PMCID: PMC1744407 DOI: 10.1136/sti.77.6.402] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Mucinases and sialidases contribute to the process of invasion and colonisation in many conditions and infections of the female reproductive tract by degrading the protective cervical mucus. The role of hydrolytic enzymes in the pathogenesis of sexually transmitted diseases and their effect on cervical mucus are discussed in this review. METHODS Articles were searched for using the keywords "sialidase," "mucinase," "protease," and "sexually transmitted infections." As well as review and other articles held by our group, searches were conducted using PubMed, Grateful Med, and the University of Bath search engine, BIDS. RESULTS Numerous publications were found describing the production of hydrolytic enzymes in sexually transmitted diseases. Because the number of publications exceeded the restrictions imposed on the size of the review, the authors selected and discussed those which they considered of the most relevance to sexually transmitted infections.
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Affiliation(s)
- R Wiggins
- Dorothy Crowfoot Hodgkin Laboratories, University Division of Medicine, Bristol Royal Infirmary, Bristol BS2 8HW, UK
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Jost BH, Songer JG, Billington SJ. Cloning, expression, and characterization of a neuraminidase gene from Arcanobacterium pyogenes. Infect Immun 2001; 69:4430-7. [PMID: 11401983 PMCID: PMC98516 DOI: 10.1128/iai.69.7.4430-4437.2001] [Citation(s) in RCA: 31] [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
Arcanobacterium pyogenes is an opportunistic pathogen, associated with suppurative infections in domestic animals. In addition to pyolysin, a pore-forming, cholesterol-binding toxin, A. pyogenes expresses a number of putative virulence factors, including several proteases and neuraminidase activity. A 3,009-bp gene, nanH, was cloned and sequenced and conferred neuraminidase activity on an Escherichia coli host strain. The predicted 107-kDa NanH protein displayed similarity to a number of bacterial neuraminidases and contained the RIP/RLP motif and five copies of the Asp box motif found in all bacterial neuraminidases. Recombinant His-tagged NanH was found to have pH and temperature optima of 5.5 to 6.0 and 55 degrees C, respectively. Insertional deletion of the nanH gene resulted in the reduction, but not absence, of neuraminidase activity, indicating the presence of a second neuraminidase gene in A. pyogenes. NanH was localized to the A. pyogenes cell wall. A. pyogenes adhered to HeLa, CHO, and MDBK cells in a washing-resistant manner. However, the nanH mutant was not defective for adherence to epithelial cells. The role of NanH in host epithelial cell adherence may be masked by the presence of a second neuraminidase in A. pyogenes.
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Affiliation(s)
- B H Jost
- Department of Veterinary Science and Microbiology, The University of Arizona, Tucson, Arizona 85721, USA.
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35
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Macfarlane S, Hopkins MJ, Macfarlane GT. Toxin synthesis and mucin breakdown are related to swarming phenomenon in Clostridium septicum. Infect Immun 2001; 69:1120-6. [PMID: 11160009 PMCID: PMC97993 DOI: 10.1128/iai.69.2.1120-1126.2001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2000] [Accepted: 10/23/2000] [Indexed: 11/20/2022] Open
Abstract
Clostridium septicum is responsible for several diseases in humans and animals. The bacterium is capable of a simple kind of multicellular behavior known as swarming. In this investigation, environmental and physiologic factors affecting growth and swarm cell formation in C. septicum were studied over a range of dilution rates (D = 0.02 to 0.65 h(-1)) in glucose-limited, glucose-excess, and mucin-limited chemostats. Cellular differentiation was observed at low specific growth rates, irrespective of the carbon and energy source, showing that swarming occurred in response to nutrient depletion. Differential expression of virulence determinants was detected in swarm cells. Hemolysin was secreted by short motile rods but not swarm cells, whereas in cultures grown with glucose, only swarm cells formed DNase, hyaluronidase, and neuraminidase. However, neuraminidase and, to a lesser degree, hyaluronidase were induced in short motile rods in mucin-limited cultures. Both swarm cells and short rods were cytotoxic to Vero cells. Mucin was chemotaxic to C. septicum, and large amounts of mucin-degrading enzymes (beta-galactosidase, N-acetyl beta-glucosaminidase, glycosulfatase, and neuraminidase) were produced. Synthesis of these enzymes was catabolite regulated. In chemostat experiments, glycosulfatase secretion occurred only in swarm cells at low dilution rates in mucin-limited cultures. Determinations of oligosaccharide utilization demonstrated that N-acetylglucosamine, galactose, and N-acetylgalactosamine were the main carbon sources for C. septicum in mucin. Neuraminic acid was not assimilated, showing that neuraminidase does not have a direct nutritional function in this pathogen.
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Affiliation(s)
- S Macfarlane
- MRC Microbiology and Gut Biology Group, University of Dundee, Dundee, United Kingdom
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Mizan S, Henk A, Stallings A, Maier M, Lee MD. Cloning and characterization of sialidases with 2-6' and 2-3' sialyl lactose specificity from Pasteurella multocida. J Bacteriol 2000; 182:6874-83. [PMID: 11092845 PMCID: PMC94810 DOI: 10.1128/jb.182.24.6874-6883.2000] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pasteurella multocida is a mucosal pathogen that colonizes the respiratory system of susceptible hosts. Most isolates of P. multocida produce sialidase activity, which may contribute to colonization of the respiratory tract or the production of lesions in an active infection. We have cloned and sequenced a sialidase gene, nanH, from a fowl cholera isolate of P. multocida. Sequence analysis of NanH revealed that it exhibited significant amino acid sequence homology with many microbial sialidases. Insertional inactivation of nanH resulted in a mutant strain that was not deficient in sialidase production. However, this mutant exhibited reduced enzyme activity and growth rate on 2-3' sialyl lactose compared to the wild type. Subsequently, we demonstrated the presence of two sialidases by cloning another sialidase gene that differed from nanH in DNA sequence and substrate specificity. NanB demonstrated activity on both 2-3' and 2-6' sialyl lactose, while NanH demonstrated activity only on 2-3' sialyl lactose. Neither enzyme liberated sialic acid from colominic acid (2-8' sialyl lactose). Recombinant E. coli containing the sialidase genes were able to utilize several sialoconjugants when they were provided as sole carbon sources in minimal medium. These data suggest that sialidases have a nutritional function and may contribute to the ability of P. multocida to colonize and persist on vertebrate mucosal surfaces.
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Affiliation(s)
- S Mizan
- Department of Medical Microbiology and Parasitology, University of Georgia, Athens, Georgia 30602, USA
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37
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Byers HL, Tarelli E, Homer KA, Hambley H, Beighton D. Growth of Viridans streptococci on human serum alpha1-acid glycoprotein. J Dent Res 1999; 78:1370-80. [PMID: 10403465 DOI: 10.1177/00220345990780071201] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Viridans streptococci have emerged as major opportunistic pathogens. We suggest that for these bacteria to proliferate in vivo and cause disease, they must utilize host tissue components. We have therefore examined the ability of all recognized species of viridans streptococci to liberate and utilize the constituent sugars of the glycans of the extensively sialylated human serum alpha1-acid glycoprotein (AGP) as the sole source of carbohydrate to support in vitro growth. Analysis of residual glycans following bacterial growth was performed by high-pH anion exchange chromatography with pulsed amperometric detection and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Only those species which produced sialidase-namely, Streptococcus oralis, S. intermedius, and S. defectivus--grew on AGP. The extent of degradation of glycans was dependent on the particular glycosidases produced by the bacteria. S. defectivus produced only a sialidase which released the terminal N-acetylneuraminic acid residues of the glycans, and the liberated sugar was utilized. S. intermedius also produced beta-galactosidase and beta-N-acetylglucosaminidase, which removed galactose and N-acetylglucosamine from desialylated glycans, all of which again were utilized by the organism. S. oralis produced beta-galactosidase, beta-N-acetylglucosaminidase, and alpha-fucosidase and novel alpha- and beta-mannosidases which were apparent only from the analysis of the residual sugars of AGP. S. oralis cleaved all the sugars from AGP except for 22% of the N-acetylglucosamine. The residual N-acetylglucosamine residues remaining were those linked to the asparagine of the peptide backbone. All the monosaccharides released by S. oralis from AGP, with the exception of fucose, were utilized. Sialidase production may be a key factor for growth of these species of viridans streptococci on glycoproteins in vivo, since they are commonly associated with extra-oral diseases, with S. oralis emerging as an important pathogen.
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Affiliation(s)
- H L Byers
- Joint Microbiology Research Unit, Faculty of Clinical Dentistry, King's College School of Medicine and Dentistry, London, United Kingdom
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38
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Tang YP, Dallas MM, Malamy MH. Characterization of the Batl (Bacteroides aerotolerance) operon in Bacteroides fragilis: isolation of a B. fragilis mutant with reduced aerotolerance and impaired growth in in vivo model systems. Mol Microbiol 1999; 32:139-49. [PMID: 10216867 DOI: 10.1046/j.1365-2958.1999.01337.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
YT135.2.8, a Tn4400' insertion mutant of Bacteroides fragilis strain TM4000, grows poorly when used to infect Monika or Chinese hamster ovary (CHO) cell monolayers and is outcompeted by wild-type strains in mixed infections. YT135.2.8 also shows defects in the rat granuloma pouch model system in monoculture and is completely outcompeted by the wild-type strain in a mixed infection. In addition, this mutant shows defects in a new model system consisting of CHO suspension cell columns. All of these defects may be explained by the finding that YT135.2.8 shows decreased tolerance to exposure to atmospheric oxygen (less aerotolerant). The monolayer growth defect (MGD) of YT135.2.8 can be influenced significantly by the presence of sulphur-containing reducing agents (cysteine, dithiothreitol, thiodiglycol) or the non-sulphur reducing agent Tris-(2-carboxylethyl)phosphine (TCEP). The defects in YT135.2.8 can be complemented by a 6.6 kb fragment of the B. fragilis chromosome. DNA sequencing of this fragment and of the regions flanking the Tn4400' insertion in the B. fragilis chromosome revealed the presence of five open reading frames, corresponding to genes bat (Bacteroides aerotolerance) A, B, C, D, E, which form the Batl operon; Tn4400' inserted within batD. All of the hypothetical proteins possess one or more membrane-spanning domains. BatA and BatB show high similarity to each other but, like BatD, they show no match to sequences of known function in the databases. BatC and BatE contain 2-4 repeated sequences similar to the tetratricopeptide repeats (TPRs) seen in many eukaryotic proteins. The function of TPR sequences in protein interactions in other systems leads to the suggestion that the Bat proteins form a complex. The Batl complex may be involved in the generation or export of reducing power equivalents to the periplasm of the B. fragilis cell.
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Affiliation(s)
- Y P Tang
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
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Domingues RM, Avelar KE, Silva e Souza W das G, Moraes SR, Antunes EN, Ferreira MC. Electrophoretic characterization of exposed outer membrane proteins in environmental and human Bacteroides fragilis strains. ZENTRALBLATT FUR BAKTERIOLOGIE : INTERNATIONAL JOURNAL OF MEDICAL MICROBIOLOGY 1998; 287:331-41. [PMID: 9638863 DOI: 10.1016/s0934-8840(98)80167-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bacteriodes fragilis isolated from aquatic environment, from infectious process and from human feces were compared as to their outer membrane protein electrophoretic profiles after staining with Coomassie blue and reacting with antibodies prepared against whole-cell antigens of a reference strain from a clinical source. A marked homogeneity was found among the strains with these methodologies. The profiles of all strains obtained after radio-iodination of the intact cell showed qualitative similarity when compared with the profiles obtained by the other methods. Thus, these data allow us to suggest the designation of the peptides observed in the autoradiograms as surface-exposed proteins. Differences observed in the autoradiograms in the expression of bands mainly detected at a molecular weight of 28 in the commensal strain 118,310 defined previously as avirulent, in addition to a distinction in the titres of agglutination with the sera tested and lower reactivity in the immunoblotting assays, suggest a relationship of the B. fragilis surface architecture with the virulence potential as well as with the origin of the strain.
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Affiliation(s)
- R M Domingues
- Instituto de Microbiologia Prof. Paulo de Góes, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Brasil
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Russo TA, Wenderoth S, Carlino UB, Merrick JM, Lesse AJ. Identification, genomic organization, and analysis of the group III capsular polysaccharide genes kpsD, kpsM, kpsT, and kpsE from an extraintestinal isolate of Escherichia coli (CP9, O4/K54/H5). J Bacteriol 1998; 180:338-49. [PMID: 9440523 PMCID: PMC106889 DOI: 10.1128/jb.180.2.338-349.1998] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Group III capsular polysaccharides (e.g., K54) of extraintestinal isolates of Escherichia coli, similar to group II capsules (e.g., K1), are important virulence traits that confer resistance to selected host defense components in vitro and potentiate systemic infection in vivo. The genomic organization of group II capsule gene clusters has been established as a serotype-specific region 2 flanked by regions 1 and 3, which contain transport genes that are highly homologous between serotypes. In contrast, the organization of group III capsule gene clusters is not well understood. However, they are defined in part by an absence of genes with significant nucleotide homology to group II capsule transport genes in regions 1 and 3. Evaluation of isogenic, TnphoA-generated, group III capsule-minus derivatives of a clinical blood isolate (CP9, O4/K54/H5) has led to the identification of homologs of the group II capsule transport genes kpsDMTE. These genes and their surrounding regions were sequenced and analyzed. The genomic organization of these genes is distinctly different from that of their group II counterparts. Although kps(K54)DMTE are significantly divergent from their group II homologs at both the DNA and protein levels phoA fusions and computer-assisted analyses suggest that their structures and functions are similar. The putative proteins Kps(K54)M and Kps(K54)T appear to be the integral membrane component and the peripheral ATP-binding component of the ABC-2 transporter family, respectively. The putative Kps(K54)E possesses features similar to those of the membrane fusion protein family that facilitates the passage of large molecules across the periplasm. At one boundary of the capsule gene cluster, a truncated kpsM (kpsM(truncated) and its 5' noncoding regulatory sequence were identified. In contrast to the complete kps(K54)M, this region was highly homologous to the group II kpsM. Fifty-three base pairs 3' from the end of kpsM(truncated) was a sequence 75% homologous to the 39-bp inverted repeat in the IS110 insertion element from Streptomyces coelicolor. Southern analysis established that two copies of this element are present in CP9. These findings are consistent with the hypothesis that CP9 previously possessed group II capsule genes and acquired group III capsule genes via IS110-mediated horizontal transfer.
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Affiliation(s)
- T A Russo
- Department of Medicine, and The Center for Microbial Pathogenesis, SUNY at Buffalo, New York 14215, USA.
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Schauer R, Kamerling JP. Chemistry, biochemistry and biology of sialic acids ☆. NEW COMPREHENSIVE BIOCHEMISTRY 1997; 29. [PMCID: PMC7147860 DOI: 10.1016/s0167-7306(08)60624-9] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Roland Schauer
- Biochemisches Institut, Christian-Albrechls-Universität zu Kiel, Germany
| | - Johannis P. Kamerling
- Bijuoet Center, Department of Bio-Organic Chemistry, Utrecht University, The Netherlands
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Straus DC, Cooley JD, Purdy CW. In vivo production of neuraminidase by Pasteurella multocida A:3 in goats after transthoracic challenge. Curr Microbiol 1996; 33:266-9. [PMID: 8824174 DOI: 10.1007/s002849900111] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Six goats were injected transthoracically with live Pasteurella multocida A:3 to examine if an extracellular enzyme, neuraminidase, was produced in vivo during infection with this organism. The principal group of goats (n = 6) each received 1 ml of live 7.5 x 10(4) cfu of P. multocida mixed with polyacrylate beads transthoracically in the left lung on day 0 and 1 ml of live P. multocida (2.2 x 10(8) cfu) mixed with polyacrylate beads transthoracically in the left lung on day 22. Six goats were used as negative controls and received 0.3 g of polyacrylate beads subcutaneously in the right flank on days 0 and 22. Serum was obtained from all animals on days 0, 7, 14, 22, 29, and 36. Preimmune sera from all animals showed no detectable antibody to P. multocida A:3 neuraminidase in an enzyme neutralization assay. None of the sera from the negative control animals demonstrated a significant antibody titer against the P. multocida A:3 neuraminidase. On day 36, serum samples from the six infected animals possessed complete enzyme-neutralizing activity. Anti-neuraminidase antibody could be detected as early as day 14 in the infected animals. These data show that neuraminidase is produced in vivo during an active P. multocida A:3 lobar infection.
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Affiliation(s)
- D C Straus
- Department of Microbiology and Immunology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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Abstract
The importance of viridans streptococci as agents of serious extra-oral diseases, including endocarditis, is now recognized. We have tested the hypothesis that the ability to utilize sialic acid as a nutrient source may play a role in the proliferation of these organisms. The type strains of the 15 presently recognized species of viridans streptococci and two clinical isolates-S. oralis (AR3), isolated from a patient with infective endocarditis, and S. intermedius (UNS35), a brain abscess isolate-were studied for their ability to utilize sialic acid. Only S. oralis, S. sanguis, S. gordonii, S. mitis ("oralis group") S. intermedius, S. anginosus, S. constellatus ("milleri group"), and S. defectivus ("nutritionally variant group") were able to use sialic acid (N-acetylneuraminic acid) efficiently as a sole carbon source. Formate, acetate, and ethanol were produced as the major metabolic end-products of sialic acid metabolism, while corresponding glucose-grown cultures produced lactate as the major metabolic end-product. Utilization of sialic acid was independent of the production of sialidase. Cell-free extracts of sialic acid-grown cultures expressed elevated levels of N-acetylneuraminate pyruvate-lyase (NPL; the first enzyme in the intracellular catabolism of sialic acid) and N-acetylglucosamine-6-phosphate (GlcNAc-6-P) deacetylase and glucosamine-6-phosphate (GlcN-6-P) deaminase (enzymes involved in the intracellular catabolism of N-acetylglucosamine). These activities were repressed by growth in the presence of glucose. The intracellular fate of sialic acid, after cleavage by NPL into N-acetylmannosamine (ManNAc) and pyruvate, is uncertain, but the elevated levels of GlcNAc-6-P deacetylase and GlcN-6-P deaminase in sialic acid-grown cells suggest that phosphorylation and isomerization are possible steps in the metabolism of ManNAc to generate an intermediate common to the pathway of N-acetylglucosamine metabolism. The species of viridans streptococci that have the ability to utilize sialic acid are those most commonly associated with extra-oral diseases, and this ability is likely to play a role in the persistence and survival of these infecting organisms in vivo.
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Affiliation(s)
- H L Byers
- Joint Microbiology Research Unit, King's College School of Medicine and Dentistry, Faculty of Clinical Dentistry, London, England
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44
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Martinez J, Steenbergen S, Vimr E. Derived structure of the putative sialic acid transporter from Escherichia coli predicts a novel sugar permease domain. J Bacteriol 1995; 177:6005-10. [PMID: 7592358 PMCID: PMC177433 DOI: 10.1128/jb.177.20.6005-6010.1995] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Catabolism of sialic acids by Escherichia coli requires the genes nanA and nanT, which were previously mapped between argG and rpoN (E.R. Vimr and F.A. Troy, J. Bacteriol. 164:845-853, 1985). This organization is confirmed and extended by physical mapping techniques. An open reading frame beginning 135 bp from the nanA translational stop codon could code for a 53,547-Da hydrophobic polypeptide predicted to contain 14 transmembrane segments. Complementation analysis confirmed that nanT is required for sialic acid uptake when expressed in trans. NanT is homologous to a putative permease encoded by open reading frame 425, which maps between leuX and fecE in the E. coli chromosome. However, unlike this hypothetical permease or previously reported monosaccharide transporters, NanT contains a centrally located domain with two additional potential membrane-spanning segments plus one amphiphilic alpha-helix that may be important for the structure and function of sialic acid-permease.
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Affiliation(s)
- J Martinez
- Department of Microbiology, University of Illinois at Urbana-Champaign 61801, USA
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45
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Roggentin P, Kleineidam RG, Schauer R. Diversity in the properties of two sialidase isoenzymes produced by Clostridium perfringens spp. BIOLOGICAL CHEMISTRY HOPPE-SEYLER 1995; 376:569-75. [PMID: 8561916 DOI: 10.1515/bchm3.1995.376.9.569] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Clostridium perfringens produces two sialidases, one of which has a molecular mass of 71 kDa and is secreted, while the 'small', 43 kDa isoenzyme remains in the cells. The secreted, higher molecular mass sialidases of two different clostridial strains, DSM756T and A99, exhibit maximum activity at pH 5.5 and at 51 or 55 degrees C, respectively. The molecular mass of both enzymes is 71 kDa in SDS-PAGE and 63 kDa as determined by gel-filtration, which indicates the absence of subunits. Natural sialidase substrates are hydrolyzed at comparably high rates, e.g. the glycoproteins fetuin and bovine submandibular gland mucin, the homopolymer colominic acid, and the ganglioside mixture from bovine brain. The partially purified 'small' isoenzyme from C. perfringens A99 cells had similar properties to the corresponding recombinant sialidase isolated from the Escherichia coli host. It is located inside the clostridial and E. coli cells and exhibits maximum activity at pH 6.1 and 37 degrees C. A relative molecular mass of 32,000 was found with FPLC gel-filtration chromatography, while primary structure analysis yielded a value of 43,000. It differs a significantly from the 'large' isoenzyme by substrate specificity. Preferred substrates are oligosaccharides, while other, more complex sialoglycoconjugates are hydrolyzed only at very low rates. alpha 2,3-linkages are hydrolyzed much faster than alpha 2,6-bonds.
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Affiliation(s)
- P Roggentin
- Biochemisches Institut, Christian-Albrechts-Universität, Kiel, Germany
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46
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Straus DC, Purdy CW. In vivo production of neuraminidase by Pasteurella haemolytica A1 in goats after transthoracic challenge. Infect Immun 1994; 62:4675-8. [PMID: 7927740 PMCID: PMC303165 DOI: 10.1128/iai.62.10.4675-4678.1994] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Nine goats were injected transthoracically with Pasteurella haemolytica A1 to determine if an extracellular bacterial enzyme, neuraminidase, was produced in vivo during infection with this organism. The principal group of goats (n = 9) each received 1 ml of 7.25 x 10(5) live P. haemolytica A1 cells in polyacrylate beads transthoracically in the left lung on days 0 and 21. Six goats were used as negative controls and received 0.3 g of polyacrylate beads subcutaneously in the right flank on days 0 and 21. Serum was obtained from all animals on days -4, 3, 7, 14, 21, 24, and 32. Preimmune serum from all animals showed no detectable antibody to P. haemolytica A1 neuraminidase in an enzyme neutralization assay. None of the sera from the negative control animals possessed a significant antibody concentration in response to the P. haemolytica A1 neuraminidase. On day 32, serum samples from the nine infected animals possessed enzyme neutralizing activity that ranged from 62% to 100%. Anti-neuraminidase antibody could be detected as early as day 14 by the enzyme neutralization assay. These data demonstrate that the enzyme neuraminidase is produced in vivo during an active P. haemolytica A1 lobar infection.
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Affiliation(s)
- D C Straus
- Department of Microbiology and Immunology, Texas Tech University Health Sciences Center, Lubbock 79430
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47
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Abstract
Sialidases are a superfamily of N-acylneuraminate-releasing (sialic-acid-releasing) exoglycosidases found mainly in higher eukaryotes and in some, mostly pathogenic, viruses, bacteria and protozoans. The functions of sialidases are poorly understood and, until recently, their biochemical and evolutionary relationships were unclear. A comparative approach has demonstrated the remarkable similarities and differences between nonviral sialidases, and is providing clues about their functions.
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Affiliation(s)
- E R Vimr
- Dept of Veterinary Pathobiology, University of Illinois, Urbana 61801
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48
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Traving C, Schauer R, Roggentin P. Gene structure of the 'large' sialidase isoenzyme from Clostridium perfringens A99 and its relationship with other clostridial nanH proteins. Glycoconj J 1994; 11:141-51. [PMID: 7804004 DOI: 10.1007/bf00731154] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Clostridium perfringens possesses two sialidase isoenzymes of different molecular weight. Almost 90% of the gene encoding the 'large' form was found on a 3.1 kb chromosomal fragment (Sau3AI) of strain A99 by hybridization with probes developed from the N-terminal protein sequence and from commonly conserved sialidase motifs ('Asp-boxes'), whereas the remaining 3'-terminal part was detected on a 2.1 kb fragment (Hind III) of chromosomal DNA. After combination of both fragments, the resulting E. coli clones expressed sialidase activity, the properties of the recombinant sialidase corresponding with those of the wild type enzyme. The entire chromosomal fragment of 3665 bp encompasses the complete sialidase gene of 2082 bp corresponding to 694 amino acids, from which a molecular weight of 72,956 for the mature protein can be deduced. The first 41 amino acids are mostly hydrophobic and probably represent a signal peptide. The sialidase structural gene follows a non-coding region with an inverted repeat and a ribosome-binding site. Upstream from the regulatory region, another open reading frame (ORF) was detected. The 3'-terminus of the sialidase structural gene is directly followed by a further ORF of unknown function, which possibly encodes a putative permease or the acylneuraminate pyruvate-lyase involved in sialic acid catabolism. The primary structure of the 'large' isoenzyme is very similar to the sialidase of Clostridium septicum (55% identical amino acids), whereas the homology with the 'small' form of the same species is comparatively low (26%).
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Affiliation(s)
- C Traving
- Biochemisches Institut der Christian-Albrechts-Universität, Kiel
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