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Hager-Mair FF, Bloch S, Schäffer C. Glycolanguage of the oral microbiota. Mol Oral Microbiol 2024. [PMID: 38515284 DOI: 10.1111/omi.12456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 02/13/2024] [Accepted: 02/13/2024] [Indexed: 03/23/2024]
Abstract
The oral cavity harbors a diverse and dynamic bacterial biofilm community which is pivotal to oral health maintenance and, if turning dysbiotic, can contribute to various diseases. Glycans as unsurpassed carriers of biological information are participating in underlying processes that shape oral health and disease. Bacterial glycoinfrastructure-encompassing compounds as diverse as glycoproteins, lipopolysaccharides (LPSs), cell wall glycopolymers, and exopolysaccharides-is well known to influence bacterial fitness, with direct effects on bacterial physiology, immunogenicity, lifestyle, and interaction and colonization capabilities. Thus, understanding oral bacterias' glycoinfrastructure and encoded glycolanguage is key to elucidating their pathogenicity mechanisms and developing targeted strategies for therapeutic intervention. Driven by their known immunological role, most research in oral glycobiology has been directed onto LPSs, whereas, recently, glycoproteins have been gaining increased interest. This review draws a multifaceted picture of the glycolanguage, with a focus on glycoproteins, manifested in prominent oral bacteria, such as streptococci, Porphyromonas gingivalis, Tannerella forsythia, and Fusobacterium nucleatum. We first define the characteristics of the different glycoconjugate classes and then summarize the current status of knowledge of the structural diversity of glycoconjugates produced by oral bacteria, describe governing biosynthetic pathways, and list biological roles of these energetically costly compounds. Additionally, we highlight emerging research on the unraveling impact of oral glycoinfrastructure on dental caries, periodontitis, and systemic conditions. By integrating current knowledge and identifying knowledge gaps, this review underscores the importance of studying the glycolanguage oral bacteria speak to advance our understanding of oral microbiology and develop novel antimicrobials.
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Affiliation(s)
- Fiona F Hager-Mair
- Department of Chemistry, NanoGlycobiology Research Group, Institute of Biochemistry, Universität für Bodenkultur Wien, Vienna, Austria
| | - Susanne Bloch
- Department of Chemistry, NanoGlycobiology Research Group, Institute of Biochemistry, Universität für Bodenkultur Wien, Vienna, Austria
- Competence Center for Periodontal Research, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria
| | - Christina Schäffer
- Department of Chemistry, NanoGlycobiology Research Group, Institute of Biochemistry, Universität für Bodenkultur Wien, Vienna, Austria
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2
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Cinar MS, Niyas A, Avci FY. Serine-rich repeat proteins: well-known yet little-understood bacterial adhesins. J Bacteriol 2024; 206:e0024123. [PMID: 37975670 PMCID: PMC10810200 DOI: 10.1128/jb.00241-23] [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] [Indexed: 11/19/2023] Open
Abstract
Serine-rich-repeat proteins (SRRPs) are large mucin-like glycoprotein adhesins expressed by a plethora of pathogenic and symbiotic Gram-positive bacteria. SRRPs play major functional roles in bacterial-host interactions, like adhesion, aggregation, biofilm formation, virulence, and pathogenesis. Through their functional roles, SRRPs aid in the development of host microbiomes but also diseases like infective endocarditis, otitis media, meningitis, and pneumonia. SRRPs comprise shared domains across different species, including two or more heavily O-glycosylated long stretches of serine-rich repeat regions. With loci that can be as large as ~40 kb and can encode up to 10 distinct glycosyltransferases that specifically facilitate SRRP glycosylation, the SRRP loci makes up a significant portion of the bacterial genome. The significance of SRRPs and their glycans in host-microbe communications is becoming increasingly evident. Studies are beginning to reveal the glycosylation pathways and mature O-glycans presented by SRRPs. Here we review the glycosylation machinery of SRRPs across species and discuss the functional roles and clinical manifestations of SRRP glycosylation.
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Affiliation(s)
- Mukaddes S. Cinar
- Department of Biochemistry, Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Afaq Niyas
- Department of Biochemistry, Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Fikri Y. Avci
- Department of Biochemistry, Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA
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3
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Chahal G, Quintana-Hayashi MP, Gaytán MO, Benktander J, Padra M, King SJ, Linden SK. Streptococcus oralis Employs Multiple Mechanisms of Salivary Mucin Binding That Differ Between Strains. Front Cell Infect Microbiol 2022; 12:889711. [PMID: 35782137 PMCID: PMC9247193 DOI: 10.3389/fcimb.2022.889711] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/20/2022] [Indexed: 11/13/2022] Open
Abstract
Streptococcus oralis is an oral commensal and opportunistic pathogen that can enter the bloodstream and cause bacteremia and infective endocarditis. Here, we investigated the mechanisms of S. oralis binding to oral mucins using clinical isolates, isogenic mutants and glycoconjugates. S. oralis bound to both MUC5B and MUC7, with a higher level of binding to MUC7. Mass spectrometry identified 128 glycans on MUC5B, MUC7 and the salivary agglutinin (SAG). MUC7/SAG contained a higher relative abundance of Lewis type structures, including Lewis b/y, sialyl-Lewis a/x and α2,3-linked sialic acid, compared to MUC5B. S. oralis subsp. oralis binding to MUC5B and MUC7/SAG was inhibited by Lewis b and Lacto-N-tetraose glycoconjugates. In addition, S. oralis binding to MUC7/SAG was inhibited by sialyl Lewis x. Binding was not inhibited by Lacto-N-fucopentaose, H type 2 and Lewis x conjugates. These data suggest that three distinct carbohydrate binding specificities are involved in S. oralis subsp. oralis binding to oral mucins and that the mechanisms of binding MUC5B and MUC7 differ. Efficient binding of S. oralis subsp. oralis to MUC5B and MUC7 required the gene encoding sortase A, suggesting that the adhesin(s) are LPXTG-containing surface protein(s). Further investigation demonstrated that one of these adhesins is the sialic acid binding protein AsaA.
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Affiliation(s)
- Gurdeep Chahal
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | | | - Meztlli O. Gaytán
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children´s Hospital, Columbus, OH, United States
| | - John Benktander
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Medea Padra
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Samantha J. King
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children´s Hospital, Columbus, OH, United States
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, United States
- Infectious Diseases Institute, The Ohio State University, Columbus, OH, United States
- *Correspondence: Sara K. Linden, ; Samantha J. King,
| | - Sara K. Linden
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
- *Correspondence: Sara K. Linden, ; Samantha J. King,
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4
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Bensing BA, Stubbs HE, Agarwal R, Yamakawa I, Luong K, Solakyildirim K, Yu H, Hadadianpour A, Castro MA, Fialkowski KP, Morrison KM, Wawrzak Z, Chen X, Lebrilla CB, Baudry J, Smith JC, Sullam PM, Iverson TM. Origins of glycan selectivity in streptococcal Siglec-like adhesins suggest mechanisms of receptor adaptation. Nat Commun 2022; 13:2753. [PMID: 35585145 PMCID: PMC9117288 DOI: 10.1038/s41467-022-30509-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 04/26/2022] [Indexed: 11/22/2022] Open
Abstract
Bacterial binding to host receptors underlies both commensalism and pathogenesis. Many streptococci adhere to protein-attached carbohydrates expressed on cell surfaces using Siglec-like binding regions (SLBRs). The precise glycan repertoire recognized may dictate whether the organism is a strict commensal versus a pathogen. However, it is currently not clear what drives receptor selectivity. Here, we use five representative SLBRs and identify regions of the receptor binding site that are hypervariable in sequence and structure. We show that these regions control the identity of the preferred carbohydrate ligand using chimeragenesis and single amino acid substitutions. We further evaluate how the identity of the preferred ligand affects the interaction with glycoprotein receptors in human saliva and plasma samples. As point mutations can change the preferred human receptor, these studies suggest how streptococci may adapt to changes in the environmental glycan repertoire.
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Affiliation(s)
- Barbara A Bensing
- Division of Infectious Diseases, Veterans Affairs Medical Center, Department of Medicine, University of California, San Francisco, CA, USA
- the Northern California Institute for Research and Education, San Francisco, CA, 94121, USA
| | - Haley E Stubbs
- Graduate Program in Chemical and Physical Biology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Rupesh Agarwal
- University of Tennessee/Oak Ridge National Laboratory, Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6309, USA
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Izumi Yamakawa
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA
- School of Nursing, Belmont University, Nashville, TN, 37212, USA
| | - Kelvin Luong
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Kemal Solakyildirim
- Department of Chemistry, Erzincan Binali Yildirim University, Erzincan, 24100, Turkey
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Hai Yu
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Azadeh Hadadianpour
- Department of Microbiology, Pathology, and Immunology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Manuel A Castro
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Kevin P Fialkowski
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA
- College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
| | - KeAndreya M Morrison
- Department of Pharmacology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, 37208, USA
| | - Zdzislaw Wawrzak
- LS-CAT Synchrotron Research Center, Northwestern University, Argonne, IL, 60439, USA
| | - Xi Chen
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Carlito B Lebrilla
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Jerome Baudry
- Department of Biological Sciences, The University of Alabama in Huntsville, Huntsville, AL, 35899, USA
| | - Jeremy C Smith
- University of Tennessee/Oak Ridge National Laboratory, Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6309, USA
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Paul M Sullam
- Division of Infectious Diseases, Veterans Affairs Medical Center, Department of Medicine, University of California, San Francisco, CA, USA
- the Northern California Institute for Research and Education, San Francisco, CA, 94121, USA
| | - T M Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA.
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA.
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5
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van Belkum A, Almeida C, Bardiaux B, Barrass SV, Butcher SJ, Çaykara T, Chowdhury S, Datar R, Eastwood I, Goldman A, Goyal M, Happonen L, Izadi-Pruneyre N, Jacobsen T, Johnson PH, Kempf VAJ, Kiessling A, Bueno JL, Malik A, Malmström J, Meuskens I, Milner PA, Nilges M, Pamme N, Peyman SA, Rodrigues LR, Rodriguez-Mateos P, Sande MG, Silva CJ, Stasiak AC, Stehle T, Thibau A, Vaca DJ, Linke D. Host-Pathogen Adhesion as the Basis of Innovative Diagnostics for Emerging Pathogens. Diagnostics (Basel) 2021; 11:diagnostics11071259. [PMID: 34359341 PMCID: PMC8305138 DOI: 10.3390/diagnostics11071259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 12/18/2022] Open
Abstract
Infectious diseases are an existential health threat, potentiated by emerging and re-emerging viruses and increasing bacterial antibiotic resistance. Targeted treatment of infectious diseases requires precision diagnostics, especially in cases where broad-range therapeutics such as antibiotics fail. There is thus an increasing need for new approaches to develop sensitive and specific in vitro diagnostic (IVD) tests. Basic science and translational research are needed to identify key microbial molecules as diagnostic targets, to identify relevant host counterparts, and to use this knowledge in developing or improving IVD. In this regard, an overlooked feature is the capacity of pathogens to adhere specifically to host cells and tissues. The molecular entities relevant for pathogen–surface interaction are the so-called adhesins. Adhesins vary from protein compounds to (poly-)saccharides or lipid structures that interact with eukaryotic host cell matrix molecules and receptors. Such interactions co-define the specificity and sensitivity of a diagnostic test. Currently, adhesin-receptor binding is typically used in the pre-analytical phase of IVD tests, focusing on pathogen enrichment. Further exploration of adhesin–ligand interaction, supported by present high-throughput “omics” technologies, might stimulate a new generation of broadly applicable pathogen detection and characterization tools. This review describes recent results of novel structure-defining technologies allowing for detailed molecular analysis of adhesins, their receptors and complexes. Since the host ligands evolve slowly, the corresponding adhesin interaction is under selective pressure to maintain a constant receptor binding domain. IVD should exploit such conserved binding sites and, in particular, use the human ligand to enrich the pathogen. We provide an inventory of methods based on adhesion factors and pathogen attachment mechanisms, which can also be of relevance to currently emerging pathogens, including SARS-CoV-2, the causative agent of COVID-19.
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Affiliation(s)
- Alex van Belkum
- BioMérieux, Open Innovation & Partnerships, 38390 La Balme Les Grottes, France;
- Correspondence: (A.v.B.); (D.L.)
| | | | - Benjamin Bardiaux
- Institut Pasteur, Structural Biology and Chemistry, 75724 Paris, France; (B.B.); (N.I.-P.); (T.J.); (M.N.)
| | - Sarah V. Barrass
- Department of Biological Sciences, University of Helsinki, 00014 Helsinki, Finland; (S.V.B.); (S.J.B.); (A.G.)
| | - Sarah J. Butcher
- Department of Biological Sciences, University of Helsinki, 00014 Helsinki, Finland; (S.V.B.); (S.J.B.); (A.G.)
| | - Tuğçe Çaykara
- Centre for Nanotechnology and Smart Materials, 4760-034 Vila Nova de Famalicão, Portugal; (T.Ç.); (C.J.S.)
| | - Sounak Chowdhury
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, 22242 Lund, Sweden; (S.C.); (L.H.); (J.M.)
| | - Rucha Datar
- BioMérieux, Microbiology R&D, 38390 La Balme Les Grottes, France;
| | | | - Adrian Goldman
- Department of Biological Sciences, University of Helsinki, 00014 Helsinki, Finland; (S.V.B.); (S.J.B.); (A.G.)
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK; (P.H.J.); (A.K.); (J.L.B.); (A.M.); (P.A.M.); (S.A.P.)
| | - Manisha Goyal
- BioMérieux, Open Innovation & Partnerships, 38390 La Balme Les Grottes, France;
| | - Lotta Happonen
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, 22242 Lund, Sweden; (S.C.); (L.H.); (J.M.)
| | - Nadia Izadi-Pruneyre
- Institut Pasteur, Structural Biology and Chemistry, 75724 Paris, France; (B.B.); (N.I.-P.); (T.J.); (M.N.)
| | - Theis Jacobsen
- Institut Pasteur, Structural Biology and Chemistry, 75724 Paris, France; (B.B.); (N.I.-P.); (T.J.); (M.N.)
| | - Pirjo H. Johnson
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK; (P.H.J.); (A.K.); (J.L.B.); (A.M.); (P.A.M.); (S.A.P.)
| | - Volkhard A. J. Kempf
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe-University, 60596 Frankfurt am Main, Germany; (V.A.J.K.); (A.T.); (D.J.V.)
| | - Andreas Kiessling
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK; (P.H.J.); (A.K.); (J.L.B.); (A.M.); (P.A.M.); (S.A.P.)
| | - Juan Leva Bueno
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK; (P.H.J.); (A.K.); (J.L.B.); (A.M.); (P.A.M.); (S.A.P.)
| | - Anchal Malik
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK; (P.H.J.); (A.K.); (J.L.B.); (A.M.); (P.A.M.); (S.A.P.)
| | - Johan Malmström
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, 22242 Lund, Sweden; (S.C.); (L.H.); (J.M.)
| | - Ina Meuskens
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway;
| | - Paul A. Milner
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK; (P.H.J.); (A.K.); (J.L.B.); (A.M.); (P.A.M.); (S.A.P.)
| | - Michael Nilges
- Institut Pasteur, Structural Biology and Chemistry, 75724 Paris, France; (B.B.); (N.I.-P.); (T.J.); (M.N.)
| | - Nicole Pamme
- School of Mathematics and Physical Sciences, University of Hull, Hull HU6 7RX, UK; (N.P.); (P.R.-M.)
| | - Sally A. Peyman
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK; (P.H.J.); (A.K.); (J.L.B.); (A.M.); (P.A.M.); (S.A.P.)
| | - Ligia R. Rodrigues
- CEB—Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal; (L.R.R.); (M.G.S.)
| | - Pablo Rodriguez-Mateos
- School of Mathematics and Physical Sciences, University of Hull, Hull HU6 7RX, UK; (N.P.); (P.R.-M.)
| | - Maria G. Sande
- CEB—Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal; (L.R.R.); (M.G.S.)
| | - Carla Joana Silva
- Centre for Nanotechnology and Smart Materials, 4760-034 Vila Nova de Famalicão, Portugal; (T.Ç.); (C.J.S.)
| | - Aleksandra Cecylia Stasiak
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany; (A.C.S.); (T.S.)
| | - Thilo Stehle
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany; (A.C.S.); (T.S.)
| | - Arno Thibau
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe-University, 60596 Frankfurt am Main, Germany; (V.A.J.K.); (A.T.); (D.J.V.)
| | - Diana J. Vaca
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe-University, 60596 Frankfurt am Main, Germany; (V.A.J.K.); (A.T.); (D.J.V.)
| | - Dirk Linke
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway;
- Correspondence: (A.v.B.); (D.L.)
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6
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Gaytán MO, Singh AK, Woodiga SA, Patel SA, An SS, Vera-Ponce de León A, McGrath S, Miller AR, Bush JM, van der Linden M, Magrini V, Wilson RK, Kitten T, King SJ. A novel sialic acid-binding adhesin present in multiple species contributes to the pathogenesis of Infective endocarditis. PLoS Pathog 2021; 17:e1009222. [PMID: 33465168 PMCID: PMC7846122 DOI: 10.1371/journal.ppat.1009222] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 01/29/2021] [Accepted: 11/30/2020] [Indexed: 02/07/2023] Open
Abstract
Bacterial binding to platelets is a key step in the development of infective endocarditis (IE). Sialic acid, a common terminal carbohydrate on host glycans, is the major receptor for streptococci on platelets. So far, all defined interactions between streptococci and sialic acid on platelets are mediated by serine-rich repeat proteins (SRRPs). However, we identified Streptococcus oralis subsp. oralis IE-isolates that bind sialic acid but lack SRRPs. In addition to binding sialic acid, some SRRP- isolates also bind the cryptic receptor β-1,4-linked galactose through a yet unknown mechanism. Using comparative genomics, we identified a novel sialic acid-binding adhesin, here named AsaA (associated with sialic acid adhesion A), present in IE-isolates lacking SRRPs. We demonstrated that S. oralis subsp. oralis AsaA is required for binding to platelets in a sialic acid-dependent manner. AsaA comprises a non-repeat region (NRR), consisting of a FIVAR/CBM and two Siglec-like and Unique domains, followed by 31 DUF1542 domains. When recombinantly expressed, Siglec-like and Unique domains competitively inhibited binding of S. oralis subsp. oralis and directly interacted with sialic acid on platelets. We further demonstrated that AsaA impacts the pathogenesis of S. oralis subsp. oralis in a rabbit model of IE. Additionally, we found AsaA orthologues in other IE-causing species and demonstrated that the NRR of AsaA from Gemella haemolysans blocked binding of S. oralis subsp. oralis, suggesting that AsaA contributes to the pathogenesis of multiple IE-causing species. Finally, our findings provide evidence that sialic acid is a key factor for bacterial-platelets interactions in a broader range of species than previously appreciated, highlighting its potential as a therapeutic target. Infective endocarditis (IE) is typically a bacterial infection of the heart valves that causes high mortality. Infective endocarditis can affect people with preexisting lesions on their heart valves (Subacute IE). These lesions contain platelets and other host factors to which bacteria can bind. Growth of bacteria and accumulation of host factors results in heart failure. Therefore, the ability of bacteria to bind platelets is key to the development of IE. Here, we identified a novel bacterial protein, AsaA, which helps bacteria bind to platelets and contributes to the development of disease. Although this virulence factor was characterized in Streptococcus oralis, a leading cause of IE, we demonstrated that AsaA is also present in several other IE-causing bacterial species and is likely relevant to their ability to cause disease. We showed that AsaA binds to sialic acid, a terminal sugar present on platelets, thereby demonstrating that sialic acid serves as a receptor for a wider range of IE-causing bacteria than previously appreciated, highlighting its potential as a therapeutic target.
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Affiliation(s)
- Meztlli O. Gaytán
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Anirudh K. Singh
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Shireen A. Woodiga
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Surina A. Patel
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Seon-Sook An
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Arturo Vera-Ponce de León
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Sean McGrath
- Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Anthony R. Miller
- Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Jocelyn M. Bush
- Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Mark van der Linden
- Institute of Medical Microbiology, German National Reference Center for Streptococci, University Hospital (RWTH), Aachen, Germany
| | - Vincent Magrini
- Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
| | - Richard K. Wilson
- Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
| | - Todd Kitten
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Samantha J. King
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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7
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Stubbs HE, Bensing BA, Yamakawa I, Sharma P, Yu H, Chen X, Sullam PM, Iverson TM. Tandem sialoglycan-binding modules in a Streptococcus sanguinis serine-rich repeat adhesin create target dependent avidity effects. J Biol Chem 2020; 295:14737-14749. [PMID: 32820052 PMCID: PMC7586212 DOI: 10.1074/jbc.ra120.014177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/29/2020] [Indexed: 01/07/2023] Open
Abstract
Sialic acid-binding immunoglobulin-like lectins (Siglec)-like domains of streptococcal serine-rich repeat (SRR) adhesins recognize sialylated glycans on human salivary, platelet, and plasma glycoproteins via a YTRY sequence motif. The SRR adhesin from Streptococcus sanguinis strain SK1 has tandem sialoglycan-binding domains and has previously been shown to bind sialoglycans with high affinity. However, both domains contain substitutions within the canonical YTRY motif, making it unclear how they interact with host receptors. To identify how the S. sanguinis strain SK1 SRR adhesin affects interactions with sialylated glycans and glycoproteins, we determined high-resolution crystal structures of the binding domains alone and with purified trisaccharides. These structural studies determined that the ligands still bind at the noncanonical binding motif, but with fewer hydrogen-bonding interactions to the protein than is observed in structures of other Siglec-like adhesins. Complementary biochemical studies identified that each of the two binding domains has a different selectivity profile. Interestingly, the binding of SK1 to platelets and plasma glycoproteins identified that the interaction to some host targets is dominated by the contribution of one binding domain, whereas the binding to other host receptors is mediated by both binding domains. These results provide insight into outstanding questions concerning the roles of tandem domains in targeting host receptors and suggest mechanisms for how pathogens can adapt to the availability of a range of related but nonidentical host receptors. They further suggest that the definition of the YTRY motif should be changed to ϕTRX, a more rigorous description of this sialic acid-recognition motif given recent findings.
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Affiliation(s)
- Haley E. Stubbs
- Graduate Program in Chemical and Physical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Barbara A. Bensing
- Department of Medicine, Veterans Affairs Medical Center, San Francisco, California, USA,Department of Medicine, University of California, San Francisco, California, USA
| | - Izumi Yamakawa
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
| | - Pankaj Sharma
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
| | - Hai Yu
- Department of Chemistry, University of California, Davis, California, USA
| | - Xi Chen
- Department of Chemistry, University of California, Davis, California, USA
| | - Paul M. Sullam
- Department of Medicine, Veterans Affairs Medical Center, San Francisco, California, USA
| | - T. M. Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA,Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA,Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA,For correspondence: T. M. Iverson,
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8
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Structure based virtual screening identifies small molecule effectors for the sialoglycan binding protein Hsa. Biochem J 2020; 477:3695-3707. [PMID: 32910185 PMCID: PMC9204803 DOI: 10.1042/bcj20200332] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 09/04/2020] [Accepted: 09/10/2020] [Indexed: 01/14/2023]
Abstract
Infective endocarditis (IE) is a cardiovascular disease often caused by bacteria of the viridans group of streptococci, which includes Streptococcus gordonii and Streptococcus sanguinis. Previous research has found that serine-rich repeat (SRR) proteins on the S. gordonii bacterial surface play a critical role in pathogenesis by facilitating bacterial attachment to sialylated glycans displayed on human platelets. Despite their important role in disease progression, there are currently no anti-adhesive drugs available on the market. Here, we performed structure-based virtual screening using an ensemble docking approach followed by consensus scoring to identify novel small molecule effectors against the sialoglycan binding domain of the SRR adhesin protein Hsa from the S. gordonii strain DL1. The screening successfully predicted nine compounds which were able to displace the native ligand (sialyl-T antigen) in an in vitro assay and bind competitively to Hsa. Furthermore, hierarchical clustering based on the MACCS fingerprints showed that eight of these small molecules do not share a common scaffold with the native ligand. This study indicates that SRR family of adhesin proteins can be inhibited by diverse small molecules and thus prevent the interaction of the protein with the sialoglycans. This opens new avenues for discovering potential drugs against IE.
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9
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Bai Y, Shang M, Xu M, Wu A, Sun L, Zheng L. Transcriptome, Phenotypic, and Virulence Analysis of Streptococcus sanguinis SK36 Wild Type and Its CcpA-Null Derivative (ΔCcpA). Front Cell Infect Microbiol 2019; 9:411. [PMID: 31867286 PMCID: PMC6904348 DOI: 10.3389/fcimb.2019.00411] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 11/19/2019] [Indexed: 12/15/2022] Open
Abstract
Catabolic control protein (CcpA) is linked to complex carbohydrate utilization and virulence factor in many bacteria species, influences the transcription of target genes by many mechanisms. To characterize the activity and regulatory mechanisms of CcpA in Streptococcus sanguinis, here, we analyzed the transcriptome of Streptococcus sanguinis SK36 and its CcpA-null derivative (ΔCcpA) using RNA-seq. Compared to the regulon of CcpA in SK36 in the RegPrecise database, we found that only minority of differentially expressed genes (DEGs) contained putative catabolite response element (cre) in their regulatory regions, indicating that many genes could have been affected indirectly by the loss of CcpA and analyzing the sequence of the promoter region using prediction tools is not a desirable method to recognize potential target genes of global regulator CcpA. Gene ontology and pathway analysis of DEGs revealed that CcpA exerts an influence predominantly involved in carbon catabolite metabolism and some amino acid catabolite pathways, which has been linked to expression of virulence genes in many pathogens and coordinately regulate the disease progression in vivo studies. However, in some scenarios, differences observed at the transcript level could not reflect the real differences at the protein level. Therefore, to confirm the differences in phenotype and virulence of SK36 and ΔCcpA, we characterized the role of CcpA in the regulation of biofilm development, EPS production and the virulence of Streptococcus sanguinis. Results showed CcpA inactivation impaired biofilm and EPS formation, and CcpA also involved in virulence in rabbit infective endocarditis model. These findings will undoubtedly contribute to investigate the mechanistic links between the global regulator CcpA and the virulence of Streptococcus sanguinis, further broaden our understanding of the relationship between basic metabolic processes and virulence.
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Affiliation(s)
- Yibo Bai
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Mengmeng Shang
- Department of Scientific Research, Peking Union Medical College Hospital (East), Beijing, China
| | - Mengya Xu
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Anyi Wu
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Luning Sun
- Department of Pathophysiology, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Lanyan Zheng
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, China
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10
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Streptococcus oralis subsp. dentisani Produces Monolateral Serine-Rich Repeat Protein Fibrils, One of Which Contributes to Saliva Binding via Sialic Acid. Infect Immun 2019; 87:IAI.00406-19. [PMID: 31308084 DOI: 10.1128/iai.00406-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 07/08/2019] [Indexed: 12/27/2022] Open
Abstract
Our studies reveal that the oral colonizer and cause of infective endocarditis Streptococcus oralis subsp. dentisani displays a striking monolateral distribution of surface fibrils. Furthermore, our data suggest that these fibrils impact the structure of adherent bacterial chains. Mutagenesis studies indicate that these fibrils are dependent on three serine-rich repeat proteins (SRRPs), here named fibril-associated protein A (FapA), FapB, and FapC, and that each SRRP forms a different fibril with a distinct distribution. SRRPs are a family of bacterial adhesins that have diverse roles in adhesion and that can bind to different receptors through modular nonrepeat region domains. Amino acid sequence and predicted structural similarity searches using the nonrepeat regions suggested that FapA may contribute to interspecies interactions, that FapA and FapB may contribute to intraspecies interactions, and that FapC may contribute to sialic acid binding. We demonstrate that a fapC mutant was significantly reduced in binding to saliva. We confirmed a role for FapC in sialic acid binding by demonstrating that the parental strain was significantly reduced in adhesion upon addition of a recombinantly expressed, sialic acid-specific, carbohydrate binding module, while the fapC mutant was not reduced. However, mutation of a residue previously shown to be essential for sialic acid binding did not decrease bacterial adhesion, leaving the precise mechanism of FapC-mediated adhesion to sialic acid to be defined. We also demonstrate that the presence of any one of the SRRPs is sufficient for efficient biofilm formation. Similar structures were observed on all infective endocarditis isolates examined, suggesting that this distribution is a conserved feature of this S. oralis subspecies.
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11
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Bensing BA, Li L, Yakovenko O, Wong M, Barnard KN, Iverson TM, Lebrilla CB, Parrish CR, Thomas WE, Xiong Y, Sullam PM. Recognition of specific sialoglycan structures by oral streptococci impacts the severity of endocardial infection. PLoS Pathog 2019; 15:e1007896. [PMID: 31233555 PMCID: PMC6611644 DOI: 10.1371/journal.ppat.1007896] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 07/05/2019] [Accepted: 06/05/2019] [Indexed: 11/18/2022] Open
Abstract
Streptococcus gordonii and Streptococcus sanguinis are primary colonizers of the tooth surface. Although generally non-pathogenic in the oral environment, they are a frequent cause of infective endocarditis. Both streptococcal species express a serine-rich repeat surface adhesin that mediates attachment to sialylated glycans on mucin-like glycoproteins, but the specific sialoglycan structures recognized can vary from strain to strain. Previous studies have shown that sialoglycan binding is clearly important for aortic valve infections caused by some S. gordonii, but this process did not contribute to the virulence of a strain of S. sanguinis. However, these streptococci can bind to different subsets of sialoglycan structures. Here we generated isogenic strains of S. gordonii that differ only in the type and range of sialoglycan structures to which they adhere and examined whether this rendered them more or less virulent in a rat model of endocarditis. The findings indicate that the recognition of specific sialoglycans can either enhance or diminish pathogenicity. Binding to sialyllactosamine reduces the initial colonization of mechanically-damaged aortic valves, whereas binding to the closely-related trisaccharide sialyl T-antigen promotes higher bacterial densities in valve tissue 72 hours later. A surprising finding was that the initial attachment of streptococci to aortic valves was inversely proportional to the affinity of each strain for platelets, suggesting that binding to platelets circulating in the blood may divert bacteria away from the endocardial surface. Importantly, we found that human and rat platelet GPIbα (the major receptor for S. gordonii and S. sanguinis on platelets) display similar O-glycan structures, comprised mainly of a di-sialylated core 2 hexasaccharide, although the rat GPIbα has a more heterogenous composition of modified sialic acids. The combined results suggest that streptococcal interaction with a minor O-glycan on GPIbα may be more important than the over-all affinity for GPIbα for pathogenic effects. Infective endocarditis (IE) is a life-threatening infection of heart valves, and streptococci that normally reside in the mouth are a leading cause of this disease. Some oral streptococcal species express a protein on their surface that enables attachment to glycan (sugar) modifications on saliva proteins, an interaction that may be important for colonization of the tooth and other oral surfaces. These "Siglec-like adhesins" are hypervariable in the type and number of glycan structures they bind, ranging from just one to more than six of the structures displayed on the saliva proteins. If streptococci enter into the bloodstream, the Siglec-like adhesin can mediate attachment to similar glycans that decorate platelet or plasma proteins, which can impact the overall virulence of the organism. This study highlights how recognition of a specific type of glycan structure can cause a generally beneficial or neutral microbe to create damage to specific tissues—in this case the heart valves, illustrating one means by which commensal bacteria can become opportunistic or accidental pathogens. The findings further indicate that certain glycan-binding streptococci among the oral microbiota may be predisposed to produce infective endocarditis.
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Affiliation(s)
- Barbara A. Bensing
- Department of Medicine, San Francisco Veterans Affairs Medical Center and University of California, San Francisco, California, United States of America
- * E-mail:
| | - Liang Li
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Olga Yakovenko
- Department of Bioengineering, University of Washington, Seattle, Washington, United States of America
| | - Maurice Wong
- Department of Chemistry, University of California, Davis, California, United States of America
| | - Karen N. Barnard
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - T. M. Iverson
- Departments of Pharmacology and Biochemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Carlito B. Lebrilla
- Department of Chemistry, University of California, Davis, California, United States of America
| | - Colin R. Parrish
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Wendy E. Thomas
- Department of Bioengineering, University of Washington, Seattle, Washington, United States of America
| | - Yan Xiong
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, California, United States of America
- David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Paul M. Sullam
- Department of Medicine, San Francisco Veterans Affairs Medical Center and University of California, San Francisco, California, United States of America
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12
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Latousakis D, MacKenzie DA, Telatin A, Juge N. Serine-rich repeat proteins from gut microbes. Gut Microbes 2019; 11:102-117. [PMID: 31035824 PMCID: PMC6973325 DOI: 10.1080/19490976.2019.1602428] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/08/2019] [Accepted: 03/27/2019] [Indexed: 02/03/2023] Open
Abstract
Serine-rich repeat proteins (SRRPs) have emerged as an important group of cell surface adhesins found in a growing number of Gram-positive bacteria. Studies focused on SRRPs from streptococci and staphylococci demonstrated that these proteins are O-glycosylated on serine or threonine residues and exported via an accessory secretion (aSec) system. In pathogens, these adhesins contribute to disease pathogenesis and represent therapeutic targets. Recently, the non-canonical aSec system has been identified in the genomes of gut microbes and characterization of their associated SRRPs is beginning to unfold, showing their role in mediating attachment and biofilm formation. Here we provide an update of the occurrence, structure, and function of SRRPs across bacteria, with emphasis on the molecular and biochemical properties of SRRPs from gut symbionts, particularly Lactobacilli. These emerging studies underscore the range of ligands recognized by these adhesins and the importance of SRRP glycosylation in the interaction of gut microbes with the host.
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Affiliation(s)
- Dimitrios Latousakis
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Donald A. MacKenzie
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Andrea Telatin
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Nathalie Juge
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
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13
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The Role of Platelets in Antimicrobial Host Defense. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00029-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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14
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Aparicio D, Torres-Puig S, Ratera M, Querol E, Piñol J, Pich OQ, Fita I. Mycoplasma genitalium adhesin P110 binds sialic-acid human receptors. Nat Commun 2018; 9:4471. [PMID: 30367053 PMCID: PMC6203739 DOI: 10.1038/s41467-018-06963-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 09/27/2018] [Indexed: 01/30/2023] Open
Abstract
Adhesion of pathogenic bacteria to target cells is a prerequisite for colonization and further infection. The main adhesins of the emerging sexually transmitted pathogen Mycoplasma genitalium, P140 and P110, interact to form a Nap complex anchored to the cell membrane. Herein, we present the crystal structures of the extracellular region of the virulence factor P110 (916 residues) unliganded and in complex with sialic acid oligosaccharides. P110 interacts only with the neuraminic acid moiety of the oligosaccharides and experiments with human cells demonstrate that these interactions are essential for mycoplasma cytadherence. Additionally, structural information provides a deep insight of the P110 antigenic regions undergoing programmed variation to evade the host immune response. These results enlighten the interplay of M. genitalium with human target cells, offering new strategies to control mycoplasma infections. How the Mycoplasma genitalium cytadhesins P140 and P110 promote host cell invasion remains poorly understood. Here, combining structural analysis with functional assays, Aparicio et al. identify the P110 domain that binds to sialylated receptors essential for mycoplasma cytadherence.
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Affiliation(s)
- David Aparicio
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC) and Maria de Maeztu Unit of Excellence, Parc Científic de Barcelona, Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Sergi Torres-Puig
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Mercè Ratera
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC) and Maria de Maeztu Unit of Excellence, Parc Científic de Barcelona, Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Enrique Querol
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Jaume Piñol
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Oscar Q Pich
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
| | - Ignacio Fita
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC) and Maria de Maeztu Unit of Excellence, Parc Científic de Barcelona, Baldiri Reixac 10, 08028, Barcelona, Spain.
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15
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Cross BW, Ruhl S. Glycan recognition at the saliva - oral microbiome interface. Cell Immunol 2018; 333:19-33. [PMID: 30274839 DOI: 10.1016/j.cellimm.2018.08.008] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 08/16/2018] [Accepted: 08/17/2018] [Indexed: 01/25/2023]
Abstract
The mouth is a first critical interface where most potentially harmful substances or pathogens contact the host environment. Adaptive and innate immune defense mechanisms are established there to inactivate or eliminate pathogenic microbes that traverse the oral environment on the way to their target organs and tissues. Protein and glycoprotein components of saliva play a particularly important role in modulating the oral microbiota and helping with the clearance of pathogens. It has long been acknowledged that glycobiological and glycoimmunological aspects play a pivotal role in oral host-microbe, microbe-host, and microbe-microbe interactions in the mouth. In this review, we aim to delineate how glycan-mediated host defense mechanisms in the oral cavity support human health. We will describe the role of glycans attached to large molecular size salivary glycoproteins which act as a first line of primordial host defense in the human mouth. We will further discuss how glycan recognition contributes to both colonization and clearance of oral microbes.
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Affiliation(s)
- Benjamin W Cross
- Department of Oral Biology, University at Buffalo, Buffalo, NY, United States
| | - Stefan Ruhl
- Department of Oral Biology, University at Buffalo, Buffalo, NY, United States.
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16
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Bensing BA, Li Q, Park D, Lebrilla CB, Sullam PM. Streptococcal Siglec-like adhesins recognize different subsets of human plasma glycoproteins: implications for infective endocarditis. Glycobiology 2018; 28:601-611. [PMID: 29796594 PMCID: PMC6054165 DOI: 10.1093/glycob/cwy052] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/21/2018] [Indexed: 12/23/2022] Open
Abstract
Streptococcus gordonii and Streptococcus sanguinis are typically found among the normal oral microbiota but can also cause infective endocarditis. These organisms express cell surface serine-rich repeat adhesins containing "Siglec-like" binding regions (SLBRs) that mediate attachment to α2-3-linked sialic acids on human glycoproteins. Two known receptors for the Siglec-like adhesins are the salivary mucin MG2/MUC7 and platelet GPIbα, and the interaction of streptococci with these targets may contribute to oral colonization and endocarditis, respectively. The SLBRs display a surprising diversity of preferences for defined glycans, ranging from highly selective to broader specificity. In this report, we characterize the glycoproteins in human plasma recognized by four SLBRs that prefer different α2-3 sialoglycan structures. We found that the SLBRs recognize a surprisingly small subset of plasma proteins that are extensively O-glycosylated. The preferred plasma protein ligands for a sialyl-T antigen-selective SLBR are proteoglycan 4 (lubricin) and inter-alpha-trypsin inhibitor heavy chain H4. Conversely, the preferred ligand for a 3'sialyllactosamine-selective SLBR is glycocalicin (the extracellular portion of platelet GPIbα). All four SLBRs recognize C1 inhibitor but detect distinctly different glycoforms of this key regulator of the complement and kallikrein protease cascades. The four plasma ligands have potential roles in thrombosis and inflammation, and each has been cited as a biomarker for one or more vascular or other diseases. The combined results suggest that the interaction of Siglec-like adhesins with different subsets of plasma glycoproteins could have a significant impact on the propensity of streptococci to establish endocardial infections.
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Affiliation(s)
- Barbara A Bensing
- Department of Medicine, San Francisco Veterans Affairs Medical Center and University of California, San Francisco, CA, USA
| | - Qiongyu Li
- Department of Chemistry, University of California, Davis, CA, USA
| | - Dayoung Park
- Department of Chemistry, University of California, Davis, CA, USA
| | | | - Paul M Sullam
- Department of Medicine, San Francisco Veterans Affairs Medical Center and University of California, San Francisco, CA, USA
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17
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Zhu B, Macleod LC, Kitten T, Xu P. Streptococcus sanguinis biofilm formation & interaction with oral pathogens. Future Microbiol 2018; 13:915-932. [PMID: 29882414 PMCID: PMC6060398 DOI: 10.2217/fmb-2018-0043] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Caries and periodontitis are the two most common human dental diseases and are caused by dysbiosis of oral flora. Although commensal microorganisms have been demonstrated to protect against pathogens and promote oral health, most previous studies have addressed pathogenesis rather than commensalism. Streptococcus sanguinis is a commensal bacterium that is abundant in the oral biofilm and whose presence is correlated with health. Here, we focus on the mechanism of biofilm formation in S. sanguinis and the interaction of S. sanguinis with caries- and periodontitis-associated pathogens. In addition, since S. sanguinis is well known as a cause of infective endocarditis, we discuss the relationship between S. sanguinis biofilm formation and its pathogenicity in endocarditis.
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Affiliation(s)
- Bin Zhu
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Lorna C Macleod
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Todd Kitten
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA 23298, USA.,Department of Microbiology & Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Ping Xu
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA 23298, USA.,Department of Microbiology & Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA.,Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA 23298, USA
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18
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Serine-Rich Repeat Adhesins Mediate Shear-Enhanced Streptococcal Binding to Platelets. Infect Immun 2018; 86:IAI.00160-18. [PMID: 29581195 DOI: 10.1128/iai.00160-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Indexed: 11/20/2022] Open
Abstract
The binding of bacteria to platelets is thought to be a central event in the pathogenesis of infective endocarditis. The serine-rich repeat (SRR) glycoproteins of viridans group streptococci have been shown to mediate platelet binding in vitro and to contribute to virulence in animal models. However, it is not known whether SRR adhesins can mediate streptococcal binding under the high fluidic shear stress conditions present on the endocardial surface. We found that three streptococcal SRR adhesins (GspB, Hsa, and SrpA) with differing structures and sialoglycan binding specificities nevertheless exhibited similar biomechanical properties. All three adhesins mediated shear-enhanced streptococcal binding to immobilized platelets through the platelet receptor GPIbα. Shear-enhanced adhesion was manifested in three ways. First, the number of circulating streptococci binding via SRR adhesins to immobilized platelet receptors peaked at 1 dyn/cm2 Second, bound streptococci switched from weak rolling to strong stationary adhesion as shear stress increased to 10 dyn/cm2 Third, while a few streptococci detached each time the flow was increased, the majority of streptococci bound to platelets remained firmly attached through 20 to 80 dyn/cm2 (shear levels typical of arteries and the endocardium). Thus, all three adhesins mediated shear-enhanced streptococcal binding to platelets under the flow conditions found in heart valves. The ability of the SRR adhesins to mediate shear-enhanced binding strongly suggests that they form catch bonds that are activated by tensile force and provides a mechanism for the selective targeting of bacteria to platelet receptors immobilized on the endocardial surface.
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19
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Structural basis for the role of serine-rich repeat proteins from Lactobacillus reuteri in gut microbe-host interactions. Proc Natl Acad Sci U S A 2018; 115:E2706-E2715. [PMID: 29507249 PMCID: PMC5866549 DOI: 10.1073/pnas.1715016115] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Gut bacteria play a key role in health and disease, but the molecular mechanisms underpinning their interaction with the host remain elusive. The serine-rich repeat proteins (SRRPs) are a family of adhesins identified in many Gram-positive pathogenic bacteria. We previously showed that beneficial bacterial species found in the gut also express SRRPs and that SRRP was required for the ability of Lactobacillus reuteri strain to colonize mice. Here, our structural and biochemical data reveal that L. reuteri SRRP adopts a β-solenoid fold not observed in other structurally characterized SRRPs and functions as an adhesin via a pH-dependent mechanism, providing structural insights into the role of these adhesins in biofilm formation of gut symbionts. Lactobacillus reuteri, a Gram-positive bacterial species inhabiting the gastrointestinal tract of vertebrates, displays remarkable host adaptation. Previous mutational analyses of rodent strain L. reuteri 100-23C identified a gene encoding a predicted surface-exposed serine-rich repeat protein (SRRP100-23) that was vital for L. reuteri biofilm formation in mice. SRRPs have emerged as an important group of surface proteins on many pathogens, but no structural information is available in commensal bacteria. Here we report the 2.00-Å and 1.92-Å crystal structures of the binding regions (BRs) of SRRP100-23 and SRRP53608 from L. reuteri ATCC 53608, revealing a unique β-solenoid fold in this important adhesin family. SRRP53608-BR bound to host epithelial cells and DNA at neutral pH and recognized polygalacturonic acid (PGA), rhamnogalacturonan I, or chondroitin sulfate A at acidic pH. Mutagenesis confirmed the role of the BR putative binding site in the interaction of SRRP53608-BR with PGA. Long molecular dynamics simulations showed that SRRP53608-BR undergoes a pH-dependent conformational change. Together, these findings provide mechanistic insights into the role of SRRPs in host–microbe interactions and open avenues of research into the use of biofilm-forming probiotics against clinically important pathogens.
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