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Wantuch PL, Knoot CJ, Robinson LS, Vinogradov E, Scott NE, Harding CM, Rosen DA. A heptavalent O-antigen bioconjugate vaccine exhibits differential functional antibody responses against diverse Klebsiella pneumoniae isolates. J Infect Dis 2024:jiae097. [PMID: 38401891 DOI: 10.1093/infdis/jiae097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/13/2024] [Accepted: 02/21/2024] [Indexed: 02/26/2024] Open
Abstract
Klebsiella pneumoniae is the leading cause of neonatal sepsis and is increasingly difficult to treat due to antibiotic resistance. Vaccination represents a tractable approach to combat this resistant bacterium; however, there is currently not a licensed vaccine. Surface polysaccharides, including O-antigens of lipopolysaccharide, have long been attractive candidates for vaccine inclusion. Herein we describe the generation of a bioconjugate vaccine targeting seven predominant O-antigen subtypes in K. pneumoniae. Each bioconjugate was immunogenic in isolation, with limited cross-reactivity among subtypes. Vaccine-induced antibodies demonstrated varying degrees of binding to a wide variety of K. pneumoniae strains. Further, sera from vaccinated mice induced complement-mediated killing of many of these strains. Finally, increased capsule interfered with O-antigen antibodies' ability to bind and mediate killing of some K. pneumoniae strains. Taken together, these data indicate that this novel heptavalent O-antigen bioconjugate vaccine formulation exhibits limited efficacy against some, but not all, K. pneumoniae isolates.
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Affiliation(s)
- Paeton L Wantuch
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | | | - Evgeny Vinogradov
- National Research Council Canada, Human Health Therapeutics Centre, Ottawa, ON K1A 0R6, Canada
| | - Nichollas E Scott
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC 3010, Australia
| | | | - David A Rosen
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110. USA
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2
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Wantuch PL, Knoot CJ, Robinson LS, Vinogradov E, Scott NE, Harding CM, Rosen DA. A heptavalent O-antigen bioconjugate vaccine exhibits differential functional antibody responses against diverse Klebsiella pneumoniae isolates. bioRxiv 2023:2023.12.12.571344. [PMID: 38168360 PMCID: PMC10760053 DOI: 10.1101/2023.12.12.571344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Klebsiella pneumoniae is a concerning pathogen that is now the leading cause of neonatal sepsis and is increasingly difficult to treat due to heightened antibiotic resistance. Thus, there is an urgent need for preventive and effective immunotherapies targeting K. pneumoniae. Vaccination represents a tractable approach to combat this resistant bacterium in some settings; however, there is currently not a licensed K. pneumoniae vaccine available. K. pneumoniae surface polysaccharides, including the terminal O-antigen polysaccharides of lipopolysaccharide, have long been attractive candidates for vaccine inclusion. Herein we describe the generation of a bioconjugate vaccine targeting seven of the predominant O-antigen subtypes in K. pneumoniae. Each of the seven bioconjugates were immunogenic in isolation, with limited cross-reactivity among subtypes. Vaccine-induced antibodies demonstrated varying degrees of binding to a wide variety of K. pneumoniae strains, including suspected hypervirulent strains, all expressing different O-antigen and capsular polysaccharide combinations. Further, sera from vaccinated mice induced complement-mediated killing of many of these K. pneumoniae strains. Finally, we found that increased quantity of capsule interferes with O-antigen antibodies' ability to bind and mediate killing of some K. pneumoniae strains, including those carrying hypervirulence-associated genes. Taken together, these data indicate that this novel heptavalent O-antigen bioconjugate vaccine formulation exhibits promising efficacy against some, but not all, K. pneumoniae isolates.
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Affiliation(s)
- Paeton L Wantuch
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | | | - Evgeny Vinogradov
- National Research Council Canada, Human Health Therapeutics Centre, Ottawa, ON K1A 0R6, Canada
| | - Nichollas E Scott
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC 3010, Australia
| | | | - David A Rosen
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110. USA
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3
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Agarwal K, Choudhury B, Robinson LS, Morrill SR, Bouchibiti Y, Chilin-Fuentes D, Rosenthal SB, Fisch KM, Peipert JF, Lebrilla CB, Allsworth JE, Lewis AL, Lewis WG. Resident microbes shape the vaginal epithelial glycan landscape. Sci Transl Med 2023; 15:eabp9599. [PMID: 38019934 DOI: 10.1126/scitranslmed.abp9599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 11/01/2023] [Indexed: 12/01/2023]
Abstract
Epithelial cells are covered in carbohydrates (glycans). This glycan coat or "glycocalyx" interfaces directly with microbes, providing a protective barrier against potential pathogens. Bacterial vaginosis (BV) is a condition associated with adverse health outcomes in which bacteria reside in direct proximity to the vaginal epithelium. Some of these bacteria, including Gardnerella, produce glycosyl hydrolase enzymes. However, glycans of the human vaginal epithelial surface have not been studied in detail. Here, we elucidate key characteristics of the "normal" vaginal epithelial glycan landscape and analyze the impact of resident microbes on the surface glycocalyx. In human BV, glycocalyx staining was visibly diminished in electron micrographs compared to controls. Biochemical and mass spectrometric analysis showed that, compared to normal vaginal epithelial cells, BV cells were depleted of sialylated N- and O-glycans, with underlying galactose residues exposed on the surface. Treatment of primary epithelial cells from BV-negative women with recombinant Gardnerella sialidases generated BV-like glycan phenotypes. Exposure of cultured VK2 vaginal epithelial cells to recombinant Gardnerella sialidase led to desialylation of glycans and induction of pathways regulating cell death, differentiation, and inflammatory responses. These data provide evidence that vaginal epithelial cells exhibit an altered glycan landscape in BV and suggest that BV-associated glycosidic enzymes may lead to changes in epithelial gene transcription that promote cell turnover and regulate responses toward the resident microbiome.
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Affiliation(s)
- Kavita Agarwal
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego (UCSD), La Jolla, CA 92093, USA
- Glycobiology Research and Training Center, UCSD, La Jolla, CA 92093, USA
| | - Biswa Choudhury
- Glycobiology Research and Training Center, UCSD, La Jolla, CA 92093, USA
| | - Lloyd S Robinson
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sydney R Morrill
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego (UCSD), La Jolla, CA 92093, USA
- Glycobiology Research and Training Center, UCSD, La Jolla, CA 92093, USA
| | - Yasmine Bouchibiti
- Department of Chemistry, University of California Davis, Davis, CA 95616, USA
- Department of Food Science and Technology, University of California Davis, Davis, CA 95616, USA
| | - Daisy Chilin-Fuentes
- Center for Computational Biology and Bioinformatics, UCSD, La Jolla, CA 92093, USA
| | - Sara B Rosenthal
- Center for Computational Biology and Bioinformatics, UCSD, La Jolla, CA 92093, USA
| | - Kathleen M Fisch
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego (UCSD), La Jolla, CA 92093, USA
- Center for Computational Biology and Bioinformatics, UCSD, La Jolla, CA 92093, USA
| | - Jeffrey F Peipert
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Carlito B Lebrilla
- Department of Chemistry, University of California Davis, Davis, CA 95616, USA
- Department of Food Science and Technology, University of California Davis, Davis, CA 95616, USA
| | - Jenifer E Allsworth
- Department of Biomedical and Health Informatics, University of Missouri, Kansas City School of Medicine, Kansas City, MO 64110, USA
| | - Amanda L Lewis
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego (UCSD), La Jolla, CA 92093, USA
- Glycobiology Research and Training Center, UCSD, La Jolla, CA 92093, USA
| | - Warren G Lewis
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego (UCSD), La Jolla, CA 92093, USA
- Glycobiology Research and Training Center, UCSD, La Jolla, CA 92093, USA
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Wantuch PL, Knoot CJ, Robinson LS, Vinogradov E, Scot NE, Harding CM, Rosen DA. Capsular polysaccharide inhibits vaccine-induced O-antigen antibody binding and function across both classical and hypervirulent K2:O1 strains of Klebsiella pneumoniae. PLoS Pathog 2023; 19:e1011367. [PMID: 37146068 DOI: 10.1371/journal.ppat.1011367] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 05/17/2023] [Accepted: 04/17/2023] [Indexed: 05/07/2023] Open
Abstract
Klebsiella pneumoniae presents as two circulating pathotypes: classical K. pneumoniae (cKp) and hypervirulent K. pneumoniae (hvKp). Classical isolates are considered urgent threats due to their antibiotic resistance profiles, while hvKp isolates have historically been antibiotic susceptible. Recently, however, increased rates of antibiotic resistance have been observed in both hvKp and cKp, further underscoring the need for preventive and effective immunotherapies. Two distinct surface polysaccharides have gained traction as vaccine candidates against K. pneumoniae: capsular polysaccharide and the O-antigen of lipopolysaccharide. While both targets have practical advantages and disadvantages, it remains unclear which of these antigens included in a vaccine would provide superior protection against matched K. pneumoniae strains. Here, we report the production of two bioconjugate vaccines, one targeting the K2 capsular serotype and the other targeting the O1 O-antigen. Using murine models, we investigated whether these vaccines induced specific antibody responses that recognize K2:O1 K. pneumoniae strains. While each vaccine was immunogenic in mice, both cKp and hvKp strains exhibited decreased O-antibody binding in the presence of capsule. Further, O1 antibodies demonstrated decreased killing in serum bactericidal assays with encapsulated strains, suggesting that the presence of K. pneumoniae capsule blocks O1-antibody binding and function. Finally, the K2 vaccine outperformed the O1 vaccine against both cKp and hvKp in two different murine infection models. These data suggest that capsule-based vaccines may be superior to O-antigen vaccines for targeting hvKp and some cKp strains, due to capsule blocking the O-antigen.
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Affiliation(s)
- Paeton L Wantuch
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Cory J Knoot
- Omniose, Saint Louis, Missouri, United States of America
| | | | - Evgeny Vinogradov
- National Research Council Canada, Human Health Therapeutics Centre, Ottawa, Ontario, Canada
| | - Nichollas E Scot
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia
| | | | - David A Rosen
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
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Knoot CJ, Wantuch PL, Robinson LS, Rosen DA, Scott NE, Harding CM. Discovery and characterization of a new class of O-linking oligosaccharyltransferases from the Moraxellaceae family. Glycobiology 2022; 33:57-74. [PMID: 36239418 PMCID: PMC9829042 DOI: 10.1093/glycob/cwac070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/07/2022] [Accepted: 10/11/2022] [Indexed: 01/12/2023] Open
Abstract
Bacterial protein glycosylation is commonly mediated by oligosaccharyltransferases (OTases) that transfer oligosaccharides en bloc from preassembled lipid-linked precursors to acceptor proteins. Natively, O-linking OTases usually transfer a single repeat unit of the O-antigen or capsular polysaccharide to the side chains of serine or threonine on acceptor proteins. Three major families of bacterial O-linking OTases have been described: PglL, PglS, and TfpO. TfpO is limited to transferring short oligosaccharides both in its native context and when heterologously expressed in glycoengineered Escherichia coli. On the other hand, PglL and PglS can transfer long-chain polysaccharides when expressed in glycoengineered E. coli. Herein, we describe the discovery and functional characterization of a novel family of bacterial O-linking OTases termed TfpM from Moraxellaceae bacteria. TfpM proteins are similar in size and sequence to TfpO enzymes but can transfer long-chain polysaccharides to acceptor proteins. Phylogenetic analyses demonstrate that TfpM proteins cluster in distinct clades from known bacterial OTases. Using a representative TfpM enzyme from Moraxella osloensis, we determined that TfpM glycosylates a C-terminal threonine of its cognate pilin-like protein and identified the minimal sequon required for glycosylation. We further demonstrated that TfpM has broad substrate tolerance and can transfer diverse glycans including those with glucose, galactose, or 2-N-acetyl sugars at the reducing end. Last, we find that a TfpM-derived bioconjugate is immunogenic and elicits serotype-specific polysaccharide IgG responses in mice. The glycan substrate promiscuity of TfpM and identification of the minimal TfpM sequon renders this enzyme a valuable additional tool for expanding the glycoengineering toolbox.
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Affiliation(s)
- Cory J Knoot
- Omniose, 4340 Duncan Ave, Suite 202, St. Louis, MO 63110, USA
| | - Paeton L Wantuch
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, 4990 Children’s Place, St. Louis, MO 63110, USA
| | | | - David A Rosen
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, 4990 Children’s Place, St. Louis, MO 63110, USA,Department of Molecular Microbiology, Washington University School of Medicine, 660 Euclid Ave, St. Louis, MO 63110, USA
| | - Nichollas E Scott
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, VIC 3010, Australia
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Duke JA, Paschall AV, Robinson LS, Knoot CJ, Vinogradov E, Scott NE, Feldman MF, Avci FY, Harding CM. Development and Immunogenicity of a Prototype Multivalent Group B Streptococcus Bioconjugate Vaccine. ACS Infect Dis 2021; 7:3111-3123. [PMID: 34633812 PMCID: PMC8793035 DOI: 10.1021/acsinfecdis.1c00415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Group B Streptococcus (GBS) is a leading cause of neonatal infections and invasive diseases in nonpregnant adults worldwide. Developing a protective conjugate vaccine targeting the capsule of GBS has been pursued for more than 30 years; however, it has yet to yield a licensed product. In this study, we present a novel bioconjugation platform for producing a prototype multivalent GBS conjugate vaccine and its subsequent analytical and immunological characterizations. Using a glycoengineering strategy, we generated strains of Escherichia coli that recombinantly express the type Ia, type Ib, and type III GBS capsular polysaccharides. We then combined the type Ia-, Ib-, and III-capsule-expressing E. coli strains with an engineered Pseudomonas aeruginosa exotoxin A (EPA) carrier protein and the PglS oligosaccharyltransferase. Coexpression of a GBS capsule, the engineered EPA protein, and PglS enabled the covalent attachment of the target GBS capsule to an engineered serine residue on EPA, all within the periplasm of E. coli. GBS bioconjugates were purified, analytically characterized, and evaluated for immunogenicity and functional antibody responses. This proof-of-concept study signifies the first step in the development of a next-generation multivalent GBS bioconjugate vaccine, which was validated by the production of conjugates that are able to elicit functional antibodies directed against the GBS capsule.
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Affiliation(s)
- Jeremy A. Duke
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United States
- Center for Molecular Medicine, University of Georgia, Athens, Georgia 30602, United States
| | - Amy V. Paschall
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United States
- Center for Molecular Medicine, University of Georgia, Athens, Georgia 30602, United States
| | | | | | - Evgeny Vinogradov
- Human Health Therapeutics Centre, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
| | - Nichollas E. Scott
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, VIC 3010, Australia
| | - Mario F. Feldman
- VaxNewMo, St. Louis, Missouri 63110, United States
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Fikri Y. Avci
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United States
- Center for Molecular Medicine, University of Georgia, Athens, Georgia 30602, United States
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Knoot CJ, Robinson LS, Harding CM. A minimal sequon sufficient for O-linked glycosylation by the versatile oligosaccharyltransferase PglS. Glycobiology 2021; 31:1192-1203. [PMID: 33997889 PMCID: PMC8457361 DOI: 10.1093/glycob/cwab043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/29/2021] [Accepted: 05/07/2021] [Indexed: 11/19/2022] Open
Abstract
Bioconjugate vaccines, consisting of polysaccharides attached to carrier proteins, are enzymatically generated using prokaryotic glycosylation systems in a process termed bioconjugation. Key to bioconjugation are a group of enzymes known as oligosaccharyltransferases (OTases) that transfer polysaccharides to engineered carrier proteins containing conserved amino acid sequences known as sequons. The most recently discovered OTase, PglS, has been shown to have the broadest substrate scope, transferring many different types of bacterial glycans including those with glucose at the reducing end. However, PglS is currently the least understood in terms of the sequon it recognizes. PglS is a pilin-specific O-linking OTase that naturally glycosylates a single protein, ComP. In addition to ComP, we previously demonstrated that an engineered carrier protein containing a large fragment of ComP is also glycosylated by PglS. Here we sought to identify the minimal ComP sequon sufficient for PglS glycosylation. We tested >100 different ComP fragments individually fused to Pseudomonas aeruginosa exotoxin A (EPA), leading to the identification of an 11-amino acid sequence sufficient for robust glycosylation by PglS. We also demonstrate that the placement of the ComP sequon on the carrier protein is critical for stability and subsequent glycosylation. Moreover, we identify novel sites on the surface of EPA that are amenable to ComP sequon insertion and find that Cross-Reactive Material 197 fused to a ComP fragment is also glycosylated. These results represent a significant expansion of the glycoengineering toolbox as well as our understanding of bacterial O-linking sequons.
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Robinson LS, Schwebke J, Lewis WG, Lewis AL. Identification and characterization of NanH2 and NanH3, enzymes responsible for sialidase activity in the vaginal bacterium Gardnerella vaginalis. J Biol Chem 2019; 294:5230-5245. [PMID: 30723162 DOI: 10.1074/jbc.ra118.006221] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 01/29/2019] [Indexed: 11/06/2022] Open
Abstract
Gardnerella vaginalis is abundant in bacterial vaginosis (BV), a condition associated with adverse reproductive health. Sialidase activity is a diagnostic feature of BV and is produced by a subset of G. vaginalis strains. Although its genetic basis has not been formally identified, sialidase activity is presumed to derive from the sialidase A gene, named here nanH1 In this study, BLAST searches predicted two additional G. vaginalis sialidases, NanH2 and NanH3. When expressed in Escherichia coli, NanH2 and NanH3 both displayed broad abilities to cleave sialic acids from α2-3- and α2-6-linked N- and O-linked sialoglycans, including relevant mucosal substrates. In contrast, recombinant NanH1 had limited activity against synthetic and mucosal substrates under the conditions tested. Recombinant NanH2 was much more effective than NanH3 in cleaving sialic acids bearing a 9-O-acetyl ester. Similarly, G. vaginalis strains encoding NanH2 cleaved and foraged significantly more Neu5,9Ac2 than strains encoding only NanH3. Among a collection of 34 G. vaginalis isolates, nanH2, nanH3, or both were present in all 15 sialidase-positive strains but absent from all 19 sialidase-negative isolates, including 16 strains that were nanH1-positive. We conclude that NanH2 and NanH3 are the primary sources of sialidase activity in G. vaginalis and that these two enzymes can account for the previously described substrate breadth cleaved by sialidases in human vaginal specimens of women with BV. Finally, PCRs of nanH2 or nanH3 from human vaginal specimens had 81% sensitivity and 78% specificity in distinguishing between Lactobacillus dominance and BV, as determined by Nugent scoring.
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Affiliation(s)
- Lloyd S Robinson
- From the Departments of Molecular Microbiology and.,Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Jane Schwebke
- the Division of Infectious Diseases, University of Alabama, Birmingham, Alabama 35294
| | - Warren G Lewis
- From the Departments of Molecular Microbiology and.,Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Amanda L Lewis
- From the Departments of Molecular Microbiology and .,Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri 63110 and.,Obstetrics and Gynecology and
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Robinson LS, Lewis WG, Lewis AL. The sialate O-acetylesterase EstA from gut Bacteroidetes species enables sialidase-mediated cross-species foraging of 9- O-acetylated sialoglycans. J Biol Chem 2017; 292:11861-11872. [PMID: 28526748 PMCID: PMC5512079 DOI: 10.1074/jbc.m116.769232] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 05/18/2017] [Indexed: 12/16/2022] Open
Abstract
The gut harbors many symbiotic, commensal, and pathogenic microbes that break down and metabolize host carbohydrates. Sialic acids are prominent outermost carbohydrates on host glycoproteins called mucins and protect underlying glycan chains from enzymatic degradation. Sialidases produced by some members of the colonic microbiota can promote the expansion of several potential pathogens (e.g. Clostridium difficile, Salmonella, and Escherichia coli) that do not produce sialidases. O-Acetyl ester modifications of sialic acids help resist the action of many sialidases and are present at high levels in the mammalian colon. However, some gut bacteria, in turn, produce sialylate-O-acetylesterases to remove them. Here, we investigated O-acetyl ester removal and sialic acid degradation by Bacteroidetes sialate-O-acetylesterases and sialidases, respectively, and subsequent utilization of host sialic acids by both commensal and pathogenic E. coli strains. In vitro foraging studies demonstrated that sialidase-dependent E. coli growth on mucin is enabled by Bacteroides EstA, a sialate O-acetylesterase acting on glycosidically linked sialylate-O-acetylesterase substrates, particularly at neutral pH. Biochemical studies suggested that spontaneous migration of O-acetyl esters on the sialic acid side chain, which can occur at colonic pH, may serve as a switch controlling EstA-assisted sialic acid liberation. Specifically, EstA did not act on O-acetyl esters in their initial 7-position. However, following migration to the 9-position, glycans with O-acetyl esters became susceptible to the sequential actions of bacterial esterases and sialidases. We conclude that EstA specifically unlocks the nutritive potential of 9-O-acetylated mucus sialic acids for foraging by bacteria that otherwise are prevented from accessing this carbon source.
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Affiliation(s)
- Lloyd S Robinson
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Warren G Lewis
- Department of Medicine, Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri 63110.
| | - Amanda L Lewis
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110.
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10
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Lewis AL, Robinson LS, Agarwal K, Lewis WG. Discovery and characterization of de novo sialic acid biosynthesis in the phylum Fusobacterium. Glycobiology 2016; 26:1107-1119. [PMID: 27613803 DOI: 10.1093/glycob/cww068] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/15/2016] [Accepted: 06/16/2016] [Indexed: 12/15/2022] Open
Abstract
Sialic acids are nine-carbon backbone carbohydrates found in prominent outermost positions of glycosylated molecules in mammals. Mimicry of sialic acid (N-acetylneuraminic acid, Neu5Ac) enables some pathogenic bacteria to evade host defenses. Fusobacterium nucleatum is a ubiquitous oral bacterium also linked with invasive infections throughout the body. We employed multidisciplinary approaches to test predictions that F. nucleatum engages in de novo synthesis of sialic acids. Here we show that F. nucleatum sbsp. polymorphum ATCC10953 NeuB (putative Neu5Ac synthase) restores Neu5Ac synthesis to an Escherichia coli neuB mutant. Moreover, purified F. nucleatum NeuB participated in synthesis of Neu5Ac from N-acetylmannosamine and phosphoenolpyruvate in vitro Further studies support the interpretation that F. nucleatum ATCC10953 NeuA encodes a functional CMP-sialic acid synthetase and suggest that it may also contain a C-terminal sialic acid O-acetylesterase. We also performed BLAST queries of F. nucleatum genomes, revealing that only 4/31 strains encode a complete pathway for de novo Neu5Ac synthesis. Biochemical studies including mass spectrometry were consistent with the bioinformatic predictions, showing that F. nucleatum ATCC10953 synthesizes high levels of Neu5Ac, whereas ATCC23726 and ATCC25586 do not express detectable levels above background. While there are a number of examples of sialic acid mimicry in other phyla, these experiments provide the first biochemical and genetic evidence that a member of the phylum Fusobacterium can engage in de novo Neu5Ac synthesis.
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Affiliation(s)
- Amanda L Lewis
- Department of Molecular Microbiology .,Department of Obstetrics and Gynecology
| | | | | | - Warren G Lewis
- Department of Medicine, Center for Women's Infectious Disease Research, 660 South Euclid Ave, Washington University School of Medicine, St. Louis, MO, USA
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Yorczyk A, Robinson LS, Ross TS. Use of panel tests in place of single gene tests in the cancer genetics clinic. Clin Genet 2014; 88:278-82. [PMID: 25318351 DOI: 10.1111/cge.12488] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 08/16/2014] [Accepted: 08/18/2014] [Indexed: 12/27/2022]
Abstract
Improved technology has made it possible to test for mutations within multiple genes simultaneously. It is not clear when these gene 'panels' should be used in the hereditary cancer setting. These analyses were intended to guide panel testing criteria. Offering hereditary panel testing as a first and final, 'single-tier', option was explored. A 'two-tiered' approach, in which panel testing is offered reflexively following stricter criteria, was then applied to the same data. Within our cohort of 105 patients, the single-tier approach was associated with a higher mutation detection rate (6.7% vs 3.8%) and variant of uncertain significance (VUS) rate (0.94 vs 0.23 average per person) compared to a two-tiered approach. Of the VUSs also identified in other patients by another lab, 53% were classified differently between laboratories. Individuals reporting African American race had more VUSs compared to other ancestry groups (p = 0.001). The test cost for a single-tier test was 21% more than a two-tiered approach. Single-tier panel testing was associated with higher mutation and VUS rates, and there is inconsistent classification of the VUS/low penetrant genes between laboratories.
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Affiliation(s)
- A Yorczyk
- Department of Cancer Genetics, University of Texas Southwestern Medical Center's Harold Simmons Comprehensive Cancer Center, Dallas, TX, USA.,Department of Cancer Genetics, University of Texas Southwestern Medical Center's Moncrief Cancer Institute, Fort Worth, TX, USA
| | - L S Robinson
- Department of Cancer Genetics, University of Texas Southwestern Medical Center's Harold Simmons Comprehensive Cancer Center, Dallas, TX, USA.,Department of Cancer Genetics, University of Texas Southwestern Medical Center's Moncrief Cancer Institute, Fort Worth, TX, USA
| | - T S Ross
- Department of Cancer Genetics, University of Texas Southwestern Medical Center's Harold Simmons Comprehensive Cancer Center, Dallas, TX, USA.,Department of Cancer Genetics, University of Texas Southwestern Medical Center's Moncrief Cancer Institute, Fort Worth, TX, USA
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Lewis WG, Robinson LS, Gilbert NM, Perry JC, Lewis AL. Degradation, foraging, and depletion of mucus sialoglycans by the vagina-adapted Actinobacterium Gardnerella vaginalis. J Biol Chem 2013; 288:12067-79. [PMID: 23479734 DOI: 10.1074/jbc.m113.453654] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Bacterial vaginosis (BV) is a polymicrobial imbalance of the vaginal microbiota associated with reproductive infections, preterm birth, and other adverse health outcomes. Sialidase activity in vaginal fluids is diagnostic of BV and sialic acid-rich components of mucus have protective and immunological roles. However, whereas mucus degradation is believed to be important in the etiology and complications associated with BV, the role(s) of sialidases and the participation of individual bacterial species in the degradation of mucus barriers in BV have not been investigated. Here we demonstrate that the BV-associated bacterium Gardnerella vaginalis uses sialidase to break down and deplete sialic acid-containing mucus components in the vagina. Biochemical evidence using purified sialoglycan substrates supports a model in which 1) G. vaginalis extracellular sialidase hydrolyzes mucosal sialoglycans, 2) liberated sialic acid (N-acetylneuraminic acid) is transported into the bacterium, a process inhibited by excess N-glycolylneuraminic acid, and 3) sialic acid catabolism is initiated by an intracellular aldolase/lyase mechanism. G. vaginalis engaged in sialoglycan foraging in vitro, in the presence of human vaginal mucus, and in vivo, in a murine vaginal model, in each case leading to depletion of sialic acids. Comparison of sialic acid levels in human vaginal specimens also demonstrated significant depletion of mucus sialic acids in women with BV compared with women with a "normal" lactobacilli-dominated microbiota. Taken together, these studies show that G. vaginalis utilizes sialidase to support the degradation, foraging, and depletion of protective host mucus barriers, and that this process of mucus barrier degradation and depletion also occurs in the clinical setting of BV.
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Affiliation(s)
- Warren G Lewis
- Departments of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA.
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Lewis WG, Robinson LS, Perry J, Bick JL, Peipert JF, Allsworth JE, Lewis AL. Hydrolysis of secreted sialoglycoprotein immunoglobulin A (IgA) in ex vivo and biochemical models of bacterial vaginosis. J Biol Chem 2011; 287:2079-89. [PMID: 22134918 DOI: 10.1074/jbc.m111.278135] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacterial vaginosis (BV) is a common polymicrobial imbalance of the vaginal flora associated with a wide variety of obstetric and gynecologic complications including serious infections and preterm birth. As evidenced by high recurrence rates following treatment, interventions for BV are still lacking. Several hydrolytic activities, including glycosidases and proteases, have been previously correlated with BV and have been hypothesized to degrade host sialoglycoproteins that participate in mucosal immune functions. Sialidase activity is most predictive of BV status and correlates strongly with adverse health outcomes. Here we combine clinical specimens with biochemical approaches to investigate secretory immunoglobulin A (SIgA) as a substrate of BV-associated glycosidases and proteases. We show that BV clinical specimens hydrolyze sialic acid from SIgA, but not in the presence of the sialidase inhibitor dehydro-deoxy-sialic acid. The collective action of BV-associated glycosidases exposes underlying mannose residues of SIgA, most apparent on the heavily N-glycosylated secretory component of the antibody. Terminal sialic acid residues on SIgA protect underlying carbohydrate residues from exposure and hydrolysis by exoglycosidases (galactosidase and hexosaminidase). It is known that both IgG and SIgA are present in the human reproductive tract. We show that the IgG heavy chain is more susceptible to proteolysis than its IgA counterpart. Gentle partial deglycosylation of the SIgA secretory component enhanced susceptibility to proteolysis. Together, these data support a model of BV in which SIgA is subject to stepwise exodeglycosylation and enhanced proteolysis, likely compromising the ability of the reproductive mucosa to neutralize and eliminate pathogens.
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Affiliation(s)
- Warren G Lewis
- Departments of Medicine, Gynecology, Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Nenninger AA, Robinson LS, Hammer ND, Epstein EA, Badtke MP, Hultgren SJ, Chapman MR. CsgE is a curli secretion specificity factor that prevents amyloid fibre aggregation. Mol Microbiol 2011; 81:486-99. [PMID: 21645131 DOI: 10.1111/j.1365-2958.2011.07706.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Curli are extracellular amyloid fibres produced by Escherichia coli that are critical for biofilm formation and adhesion to biotic and abiotic surfaces. CsgA and CsgB are the major and minor curli subunits, respectively, while CsgE, CsgF and CsgG direct the extracellular localization and assembly of curli subunits into fibres. The secretion and stability of CsgA and CsgB are dependent on the outer membrane lipoprotein CsgG. Here, we identified functional interactions between CsgG and CsgE during curli secretion. We discovered that CsgG overexpression restored curli production to a csgE strain under curli-inducing conditions. In antibiotic sensitivity and protein secretion assays, CsgG expression alone allowed translocation of erythromycin and small periplasmic proteins across the outer membrane. Coexpression of CsgE with CsgG blocked non-specific protein and antibiotic passage across the outer membrane. However, CsgE did not block secretion of proteins containing a 22-amino-acid putative outer membrane secretion signal of CsgA (A22). Finally, using purified proteins, we found that CsgE prohibited the self-assembly of CsgA into amyloid fibres. Collectively, these data indicate that CsgE provides substrate specificity to the curli secretion pore CsgG, and acts directly on the secretion substrate CsgA to prevent premature subunit assembly.
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Affiliation(s)
- Ashley A Nenninger
- Department of Molecular Microbiology and Microbial Pathogenesis, Washington University School of Medicine, Campus Box 8230, 660 S. Euclid Avenue, St Louis, MO 63110, USA
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Abstract
Produced by many Enterobacteriaceae spp., curli are biologically important amyloid fibres that have been associated with biofilm formation, host cell adhesion and invasion, and immune system activation. CsgA is the major fibre subunit and CsgE, CsgF and CsgG are non-structural proteins involved in curli biogenesis. We have characterized the role of CsgG in curli subunit secretion across the outer membrane. Directed mutagenesis of CsgG confirmed that its activity is dependent on localization to the outer membrane. Rotary Shadow electron microscopy of purified CsgG suggested that this protein assembles into an oligomeric complex with an apparent central pore. Oligomeric CsgG complexes were confirmed using co-purification experiments. Antibiotic sensitivity assays demonstrated that overexpression of CsgG rendered Escherichia coli susceptible to the antibiotic erythromycin. A 22-amino-acid sequence at the N-terminus of CsgA was sufficient to direct heterologous proteins to the CsgG secretion apparatus. Finally, we determined that CsgG participates in an outer membrane complex with two other curli assembly proteins, CsgE and CsgF.
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Affiliation(s)
- Lloyd S. Robinson
- Department of Molecular Microbiology and Microbial Pathogenesis, Box 8230, Washington University School of Medicine, 660S. Euclid Ave, St Louis, MO 63110, USA
| | - Elisabeth M. Ashman
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University, Ann Arbor, MI 48109, USA
| | - Scott J. Hultgren
- Department of Molecular Microbiology and Microbial Pathogenesis, Box 8230, Washington University School of Medicine, 660S. Euclid Ave, St Louis, MO 63110, USA
| | - Matthew R. Chapman
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University, Ann Arbor, MI 48109, USA
- For correspondence. ; Tel. (+1) 734 764 7592; Fax (+1) 734 647 0884
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Chapman MR, Robinson LS, Pinkner JS, Roth R, Heuser J, Hammar M, Normark S, Hultgren SJ. Role of Escherichia coli curli operons in directing amyloid fiber formation. Science 2002; 295:851-5. [PMID: 11823641 PMCID: PMC2838482 DOI: 10.1126/science.1067484] [Citation(s) in RCA: 906] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Amyloid is associated with debilitating human ailments including Alzheimer's and prion diseases. Biochemical, biophysical, and imaging analyses revealed that fibers produced by Escherichia coli called curli were amyloid. The CsgA curlin subunit, purified in the absence of the CsgB nucleator, adopted a soluble, unstructured form that upon prolonged incubation assembled into fibers that were indistinguishable from curli. In vivo, curli biogenesis was dependent on the nucleation-precipitation machinery requiring the CsgE and CsgF chaperone-like and nucleator proteins, respectively. Unlike eukaryotic amyloid formation, curli biogenesis is a productive pathway requiring a specific assembly machinery.
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Affiliation(s)
- Matthew R Chapman
- Department of Molecular Microbiology and Microbial Pathogenesis, Box 8230, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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Abstract
SigD is translocated into eucaryotic cells by a type III secretion system. In this work, evidence that the putative chaperone SigE directly interacts with SigD is presented. A bacterial two-hybrid system demonstrated that SigE can interact with itself and SigD. In addition, SigD was specifically copurified with SigE-His(6) on a nickel column.
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Affiliation(s)
- K H Darwin
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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