1
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Xue Y, Wu Z, Kang X. Crystal structure of the long Rib domain of the LPXTG-anchored surface protein from Limosilactobacillus reuteri. Acta Crystallogr F Struct Biol Commun 2024; 80:92-97. [PMID: 38699970 PMCID: PMC11134729 DOI: 10.1107/s2053230x24003868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 04/27/2024] [Indexed: 05/05/2024] Open
Abstract
The Rib domain, which is often found as tandem-repeat structural modules in surface proteins of Gram-positive bacteria, plays important roles in mediating interactions of bacteria with their environments and hosts. A comprehensive structural analysis of various Rib domains is essential to fully understand their impact on the structure and functionality of these bacterial adhesins. To date, structural information has been limited for this expansive group of domains. In this study, the high-resolution crystal structure of the second member of the long Rib domain, a unique subclass within the Rib-domain family, derived from Limosilactobacillus reuteri is presented. The data not only demonstrate a highly conserved structure within the long Rib domain, but also highlight an evolutionary convergence in structural architecture with other modular domains found in cell-adhesion molecules.
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Affiliation(s)
- Yi Xue
- Institute of Drug Discovery Technology, Ningbo University, Ningbo, Zhejiang 315211, People’s Republic of China
| | - Zhen Wu
- College of Food Science and Engineering, Ningbo University, Ningbo, Zhejiang 315211, People’s Republic of China
| | - Xue Kang
- Institute of Drug Discovery Technology, Ningbo University, Ningbo, Zhejiang 315211, People’s Republic of China
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2
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Di Carluccio C, Cerofolini L, Moreira M, Rosu F, Padilla-Cortés L, Gheorghita GR, Xu Z, Santra A, Yu H, Yokoyama S, Gray TE, St. Laurent CD, Manabe Y, Chen X, Fukase K, Macauley MS, Molinaro A, Li T, Bensing BA, Marchetti R, Gabelica V, Fragai M, Silipo A. Molecular Insights into O-Linked Sialoglycans Recognition by the Siglec-Like SLBR-N (SLBR UB10712) of Streptococcus gordonii. ACS CENTRAL SCIENCE 2024; 10:447-459. [PMID: 38435526 PMCID: PMC10906241 DOI: 10.1021/acscentsci.3c01598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/23/2024] [Accepted: 01/23/2024] [Indexed: 03/05/2024]
Abstract
Streptococcus gordonii is a Gram-positive bacterial species that typically colonizes the human oral cavity, but can also cause local or systemic diseases. Serine-rich repeat (SRR) glycoproteins exposed on the S. gordonii bacterial surface bind to sialylated glycans on human salivary, plasma, and platelet glycoproteins, which may contribute to oral colonization as well as endocardial infections. Despite a conserved overall domain organization of SRR adhesins, the Siglec-like binding regions (SLBRs) are highly variable, affecting the recognition of a wide range of sialoglycans. SLBR-N from the SRR glycoprotein of S. gordonii UB10712 possesses the remarkable ability to recognize complex core 2 O-glycans. We here employed a multidisciplinary approach, including flow cytometry, native mass spectrometry, isothermal titration calorimetry, NMR spectroscopy from both protein and ligand perspectives, and computational methods, to investigate the ligand specificity and binding preferences of SLBR-N when interacting with mono- and disialylated core 2 O-glycans. We determined the means by which SLBR-N preferentially binds branched α2,3-disialylated core 2 O-glycans: a selected conformation of the 3'SLn branch is accommodated into the main binding site, driving the sTa branch to further interact with the protein. At the same time, SLBR-N assumes an open conformation of the CD loop of the glycan-binding pocket, allowing one to accommodate the entire complex core 2 O-glycan. These findings establish the basis for the generation of novel tools for the detection of specific complex O-glycan structures and pave the way for the design and development of potential therapeutics against streptococcal infections.
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Affiliation(s)
- Cristina Di Carluccio
- Department
of Chemical Sciences, University of Naples
Federico II, Naples 80138, Italy
| | - Linda Cerofolini
- Magnetic
Resonance Centre (CERM), CIRMMP, and Department of Chemistry “Ugo
Schiff”, University of Florence, Sesto Fiorentino 50019, Italy
| | - Miguel Moreira
- Department
of Chemical Sciences, University of Naples
Federico II, Naples 80138, Italy
| | - Frédéric Rosu
- IECB
Institut Européen de Chimie et Biologie, Pessac 33600, France
| | - Luis Padilla-Cortés
- Magnetic
Resonance Centre (CERM), CIRMMP, and Department of Chemistry “Ugo
Schiff”, University of Florence, Sesto Fiorentino 50019, Italy
| | - Giulia Roxana Gheorghita
- Magnetic
Resonance Centre (CERM), CIRMMP, and Department of Chemistry “Ugo
Schiff”, University of Florence, Sesto Fiorentino 50019, Italy
- Giotto
Biotech s.r.l., Sesto Fiorentino 50019, Italy
| | - Zhuojia Xu
- Shanghai
Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Abhishek Santra
- Department
of Chemistry, University of California,
Davis, Davis, California 95616, United States
| | - Hai Yu
- Department
of Chemistry, University of California,
Davis, Davis, California 95616, United States
| | - Shinji Yokoyama
- Graduate
School of Science, Osaka University, Osaka 565-0871, Japan
| | - Taylor E. Gray
- Department
of Chemistry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Chris D. St. Laurent
- Department
of Chemistry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Yoshiyuki Manabe
- Graduate
School of Science, Osaka University, Osaka 565-0871, Japan
| | - Xi Chen
- Department
of Chemistry, University of California,
Davis, Davis, California 95616, United States
| | - Koichi Fukase
- Graduate
School of Science, Osaka University, Osaka 565-0871, Japan
| | - Matthew S. Macauley
- Department
of Chemistry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
- Department
of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Antonio Molinaro
- Department
of Chemical Sciences, University of Naples
Federico II, Naples 80138, Italy
- Graduate
School of Science, Osaka University, Osaka 565-0871, Japan
| | - Tiehai Li
- Shanghai
Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Barbara A. Bensing
- San
Francisco Veterans Affairs Medical Center and University of California, San Francisco, California 94121, United States
| | - Roberta Marchetti
- Department
of Chemical Sciences, University of Naples
Federico II, Naples 80138, Italy
| | - Valérie Gabelica
- IECB
Institut Européen de Chimie et Biologie, Pessac 33600, France
| | - Marco Fragai
- Magnetic
Resonance Centre (CERM), CIRMMP, and Department of Chemistry “Ugo
Schiff”, University of Florence, Sesto Fiorentino 50019, Italy
| | - Alba Silipo
- Department
of Chemical Sciences, University of Naples
Federico II, Naples 80138, Italy
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3
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SssP1, a Fimbria-like component of Streptococcus suis, binds to the vimentin of host cells and contributes to bacterial meningitis. PLoS Pathog 2022; 18:e1010710. [PMID: 35853077 PMCID: PMC9337661 DOI: 10.1371/journal.ppat.1010710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 07/29/2022] [Accepted: 06/27/2022] [Indexed: 11/19/2022] Open
Abstract
Streptococcus suis (S. suis) is one of the important pathogens that cause bacterial meningitis in pigs and humans. Evading host immune defences and penetrating the blood-brain barrier (BBB) are the preconditions for S. suis to cause meningitis, while the underlying mechanisms during these pathogenic processes are not fully understood. By detecting the red blood and white blood cells counts, IL-8 expression, and the pathological injury of brain in a mouse infection model, a serine-rich repeat (SRR) glycoprotein, designated as SssP1, was identified as a critical facilitator in the process of causing meningitis in this study. SssP1 was exported to assemble a fimbria-like component, thus contributed to the bacterial adhesion to and invasion into human brain microvascular endothelial cells (HBMECs), and activates the host inflammatory response during meningitis but is not involved in the actin cytoskeleton rearrangement and the disruption of tight junctions. Furthermore, the deletion of sssP1 significantly attenuates the ability of S. suis to traverse the BBB in vivo and in vitro. A pull-down analysis identified vimentin as the potential receptors of SssP1 during meningitis and following Far-Western blot results confirmed this ligand-receptor binding mediated by the NR2 (the second nonrepeat region) region of SssP1. The co-localisation of vimentin and S. suis observed by laser scanning confocal microscopy with multiplex fluorescence indicated that vimentin significantly enhances the interaction between SssP1 and BBB. Further study identified that the NR216-781 and NR1711-2214 fragments of SssP1 play critical roles to bind to the BBB depending on the sialylation of vimentin, and this binding is significantly attenuated when the antiserum of NR216-781 or NR1711-2214 blocked the bacterial cells, or the vimentin antibody blocked the BBB. Similar binding attenuations are observed when the bacterial cells were preincubated with the vimentin, or the BBB was preincubated with the recombinant protein NR216-781, NR1711-2214 or sialidase. In conclusion, these results reveal a novel receptor-ligand interaction that enhances adhesion to and penetration of the BBB to cause bacterial meningitis in the S. suis infection and highlight the importance of vimentin in host-pathogen interactions. Streptococcus suis (S. suis) is considered an important zoonotic pathogen capable of causing meningitis in humans. Penetrating the blood-brain barrier (BBB) is one of the preconditions for S. suis to cause meningitis, while its underlying mechanism is incompletely understood. Here we identified a previously uncharacterised pathogenic mechanism associated with S. suis meningitis mediated by the interaction between bacterial SRR glycoproteins and a host cytoskeletal component. During the bacterial infection, SRR protein SssP1 is exported to assemble a fimbria-like component, which drives a strong binding effect with the BBB depending on the sialylation of vimentin. This interaction contributes to the bacterial adhesion to and penetration of the BBB and induces a robust inflammatory response during meningitis. This overall observation underscores the significance of host cell surface vimentin interactions in microbial pathogenesis and markedly improves our understanding of host barrier penetration during meningitis.
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4
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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: 1] [Impact Index Per Article: 0.5] [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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5
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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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6
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Type IV Pili of Streptococcus sanguinis Contribute to Pathogenesis in Experimental Infective Endocarditis. Microbiol Spectr 2021; 9:e0175221. [PMID: 34756087 PMCID: PMC8579931 DOI: 10.1128/spectrum.01752-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus sanguinis is a common cause of infective endocarditis (IE). Efforts by research groups are aimed at identifying and characterizing virulence factors that contribute to the ability of this organism to cause IE. This Gram-positive pathogen causes heart infection by gaining access to the bloodstream, adhering to host extracellular matrix protein and/or platelets, colonizing the aortic endothelium, and incorporating itself into the aortic vegetation. While many virulence factors have been reported to contribute to the ability of S. sanguinis to cause IE, it is noteworthy that type IV pili (T4P) have not been described to be a virulence factor in this organism, although S. sanguinis strains typically encode these pili. Type IV pili are molecular machines that are capable of mediating diverse virulence functions and surface motility. T4P have been shown to mediate twitching motility in some strains of S. sanguinis, although in most strains it has been difficult to detect twitching motility. While we found that T4P are dispensable for direct in vitro platelet binding and aggregation phenotypes, we show that they are critical to the development of platelet-dependent biofilms representative of the cardiac vegetation. We also observed that T4P are required for in vitro invasion of S. sanguinis into human aortic endothelial cells, which indicates that S. sanguinis may use T4P to take advantage of an intracellular niche during infection. Importantly, we show that T4P of S. sanguinis are critical to disease progression (vegetation development) in a native valve IE rabbit model. The results presented here expand our understanding of IE caused by S. sanguinis and identify T4P as an important virulence factor for this pathogen. IMPORTANCE This work provides evidence that type IV pili produced by Streptococcus sanguinis SK36 are critical to the ability of these bacteria to attach to and colonize the aortic heart valve (endocarditis). We found that an S. sanguinis type IV pili mutant strain was defective in causing platelet-dependent aggregation in a 24-h infection assay but not in a 1-h platelet aggregation assay, suggesting that the type IV pili act at later stages of vegetation development. In a rabbit model of disease, a T4P mutant strain does not develop mature vegetations that form on the heart, indicating that this virulence factor is critical to disease and could be a target for IE therapy.
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7
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Hu Y, Chen F, Ye H, Lu B. Integrative analysis of the gut microbiome and metabolome in a rat model with stress induced irritable bowel syndrome. Sci Rep 2021; 11:17596. [PMID: 34475489 PMCID: PMC8413334 DOI: 10.1038/s41598-021-97083-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 08/11/2021] [Indexed: 11/29/2022] Open
Abstract
Stress is one of the major causes of irritable bowel syndrome (IBS), which is well-known for perturbing the microbiome and exacerbating IBS-associated symptoms. However, changes in the gut microbiome and metabolome in response to colorectal distention (CRD), combined with restraint stress (RS) administration, remains unclear. In this study, CRD and RS stress were used to construct an IBS rat model. The 16S rRNA gene sequencing was used to characterize the microbiota in ileocecal contents. UHPLC-QTOF-MS/MS assay was used to characterize the metabolome of gut microbiota. As a result, significant gut microbial dysbiosis was observed in stress-induced IBS rats, with the obvious enrichment of three and depletion of 11 bacterial taxa in IBS rats, when compared with those in the control group (q < 0.05). Meanwhile, distinct changes in the fecal metabolic phenotype of stress-induced IBS rats were also found, including five increased and 19 decreased metabolites. Furthermore, phenylalanine, tyrosine and tryptophan biosynthesis were the main metabolic pathways induced by IBS stress. Moreover, the altered gut microbiota had a strong correlation with the changes in metabolism of stress-induced IBS rats. Prevotella bacteria are correlated with the metabolism of 1-Naphthol and Arg.Thr. In conclusion, the gut microbiome, metabolome and their interaction were altered. This may be critical for the development of stress-induced IBS.
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Affiliation(s)
- Yue Hu
- Department of Gastroenterology, First Affiliated Hospital of Zhejiang Chinese Medical University, 54 Youdian Road, Hangzhou, 310006, Zhejiang, China
| | - Fang Chen
- Department of Gastroenterology, Zhejiang Integrated Traditional and Western Medicine Hospital, Hangzhou, Zhejiang, China
| | - Haiyong Ye
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Bin Lu
- Department of Gastroenterology, First Affiliated Hospital of Zhejiang Chinese Medical University, 54 Youdian Road, Hangzhou, 310006, Zhejiang, China.
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8
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van Sorge NM, Bonsor DA, Deng L, Lindahl E, Schmitt V, Lyndin M, Schmidt A, Nilsson OR, Brizuela J, Boero E, Sundberg EJ, van Strijp JAG, Doran KS, Singer BB, Lindahl G, McCarthy AJ. Bacterial protein domains with a novel Ig-like fold target human CEACAM receptors. EMBO J 2021; 40:e106103. [PMID: 33522633 PMCID: PMC8013792 DOI: 10.15252/embj.2020106103] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 12/08/2020] [Accepted: 12/10/2020] [Indexed: 01/19/2023] Open
Abstract
Streptococcus agalactiae, also known as group B Streptococcus (GBS), is the major cause of neonatal sepsis in humans. A critical step to infection is adhesion of bacteria to epithelial surfaces. GBS adhesins have been identified to bind extracellular matrix components and cellular receptors. However, several putative adhesins have no host binding partner characterised. We report here that surface‐expressed β protein of GBS binds to human CEACAM1 and CEACAM5 receptors. A crystal structure of the complex showed that an IgSF domain in β represents a novel Ig‐fold subtype called IgI3, in which unique features allow binding to CEACAM1. Bioinformatic assessment revealed that this newly identified IgI3 fold is not exclusively present in GBS but is predicted to be present in adhesins from other clinically important human pathogens. In agreement with this prediction, we found that CEACAM1 binds to an IgI3 domain found in an adhesin from a different streptococcal species. Overall, our results indicate that the IgI3 fold could provide a broadly applied mechanism for bacteria to target CEACAMs.
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Affiliation(s)
- Nina M van Sorge
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Daniel A Bonsor
- Institute of Human Virology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Liwen Deng
- Department of Immunology & Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Erik Lindahl
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Verena Schmitt
- Institute of Anatomy, Medical Faculty, University Duisburg-Essen, Essen, Germany
| | - Mykola Lyndin
- Institute of Anatomy, Medical Faculty, University Duisburg-Essen, Essen, Germany.,Department of Pathology, Sumy State University, Sumy, Ukraine
| | - Alexej Schmidt
- Department of Medical Biosciences, Umeå University, Pathology, Umeå, Sweden
| | - Olof R Nilsson
- Department of Laboratory Medicine, Division of Medical Microbiology, Lund University, Lund, Sweden
| | - Jaime Brizuela
- Department of Infectious Disease, MRC Centre for Molecular Bacteriology & Infection, Imperial College London, London, UK
| | - Elena Boero
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Eric J Sundberg
- Institute of Human Virology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD, USA.,Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Jos A G van Strijp
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Kelly S Doran
- Department of Immunology & Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Bernhard B Singer
- Institute of Anatomy, Medical Faculty, University Duisburg-Essen, Essen, Germany
| | - Gunnar Lindahl
- Department of Laboratory Medicine, Division of Medical Microbiology, Lund University, Lund, Sweden.,Department of Chemistry, Division of Applied Microbiology, Lund University, Lund, Sweden
| | - Alex J McCarthy
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.,Department of Infectious Disease, MRC Centre for Molecular Bacteriology & Infection, Imperial College London, London, UK
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9
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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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10
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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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11
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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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12
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Vizarraga D, Kawamoto A, Matsumoto U, Illanes R, Pérez-Luque R, Martín J, Mazzolini R, Bierge P, Pich OQ, Espasa M, Sanfeliu I, Esperalba J, Fernández-Huerta M, Scheffer MP, Pinyol J, Frangakis AS, Lluch-Senar M, Mori S, Shibayama K, Kenri T, Kato T, Namba K, Fita I, Miyata M, Aparicio D. Immunodominant proteins P1 and P40/P90 from human pathogen Mycoplasma pneumoniae. Nat Commun 2020; 11:5188. [PMID: 33057023 PMCID: PMC7560827 DOI: 10.1038/s41467-020-18777-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 09/08/2020] [Indexed: 12/19/2022] Open
Abstract
Mycoplasma pneumoniae is a bacterial human pathogen that causes primary atypical pneumonia. M. pneumoniae motility and infectivity are mediated by the immunodominant proteins P1 and P40/P90, which form a transmembrane adhesion complex. Here we report the structure of P1, determined by X-ray crystallography and cryo-electron microscopy, and the X-ray structure of P40/P90. Contrary to what had been suggested, the binding site for sialic acid was found in P40/P90 and not in P1. Genetic and clinical variability concentrates on the N-terminal domain surfaces of P1 and P40/P90. Polyclonal antibodies generated against the mostly conserved C-terminal domain of P1 inhibited adhesion of M. pneumoniae, and serology assays with sera from infected patients were positive when tested against this C-terminal domain. P40/P90 also showed strong reactivity against human infected sera. The architectural elements determined for P1 and P40/P90 open new possibilities in vaccine development against M. pneumoniae infections.
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Affiliation(s)
- David Vizarraga
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Akihiro Kawamoto
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - U Matsumoto
- Graduate School of Science, Osaka City University, Osaka, 558-8585, Japan
| | - Ramiro Illanes
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Rosa Pérez-Luque
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Jesús Martín
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Rocco Mazzolini
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr Aiguader 88, 08003, Barcelona, Spain
| | - Paula Bierge
- Laboratori de Recerca en Microbiologia i Malalties Infeccioses, Institut d'Investigació i Innovació Parc Taulí (I3PT), Hospital Universitari Parc Taulí, Universitat Autònoma de Barcelona, 08208, Sabadell, Spain
| | - Oscar Q Pich
- Laboratori de Recerca en Microbiologia i Malalties Infeccioses, Institut d'Investigació i Innovació Parc Taulí (I3PT), Hospital Universitari Parc Taulí, Universitat Autònoma de Barcelona, 08208, Sabadell, Spain.,Departament de Bioquímica i Biologia Molecular, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Mateu Espasa
- Departament de Microbiologia, Hospital Universitari Parc Taulí, Universitat Autònoma de Barcelona, 08208, Sabadell, Spain
| | - Isabel Sanfeliu
- Departament de Microbiologia, Hospital Universitari Parc Taulí, Universitat Autònoma de Barcelona, 08208, Sabadell, Spain
| | - Juliana Esperalba
- Departament de Microbiologia, Hospital Universitari Vall d´Hebron, Universitat Autònoma de Barcelona, 08035, Barcelona, Spain
| | - Miguel Fernández-Huerta
- Departament de Microbiologia, Hospital Universitari Vall d´Hebron, Universitat Autònoma de Barcelona, 08035, Barcelona, Spain
| | - Margot P Scheffer
- Buchmann Institute for Molecular Life Sciences, Max-von-Laue Str. 15, 60438, Frankfurt, Germany
| | - Jaume Pinyol
- Departament de Bioquímica i Biologia Molecular, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Achilleas S Frangakis
- Buchmann Institute for Molecular Life Sciences, Max-von-Laue Str. 15, 60438, Frankfurt, Germany
| | - Maria Lluch-Senar
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr Aiguader 88, 08003, Barcelona, Spain
| | - Shigetarou Mori
- Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Keigo Shibayama
- Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tsuyoshi Kenri
- Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Takayuki Kato
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,RIKEN Center for Biosystems Dynamics Research and SPring-8 Center, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,JEOL YOKOGUSHI Research Alliance Laboratories, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Ignacio Fita
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Makoto Miyata
- Graduate School of Science, Osaka City University, Osaka, 558-8585, Japan. .,The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, Osaka, 558-8585, Japan.
| | - David Aparicio
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10, 08028, Barcelona, Spain.
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13
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Martini AM, Moricz BS, Ripperger AK, Tran PM, Sharp ME, Forsythe AN, Kulhankova K, Salgado-Pabón W, Jones BD. Association of Novel Streptococcus sanguinis Virulence Factors With Pathogenesis in a Native Valve Infective Endocarditis Model. Front Microbiol 2020; 11:10. [PMID: 32082276 PMCID: PMC7005726 DOI: 10.3389/fmicb.2020.00010] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 01/06/2020] [Indexed: 12/11/2022] Open
Abstract
Streptococcus sanguinis (S. sanguinis) is an abundant oral commensal which can cause disseminated human infection if it gains access to the bloodstream. The most important among these diseases is infective endocarditis (IE). While virulence phenotypes of S. sanguinis have been correlated to disease severity, genetic factors mediating these phenotypes, and contributing to pathogenesis are largely uncharacterized. In this report, we investigate the roles of 128 genes in virulence-related phenotypes of S. sanguinis and characterize the pathogenic potential of two selected mutants in a left-sided, native valve IE rabbit model. Assays determining the ability of our mutant strains to produce a biofilm, bind to and aggregate platelets, and adhere to or invade endothelial cells identified sixteen genes with novel association to these phenotypes. These results suggest the presence of many uncharacterized genes involved in IE pathogenesis which may be relevant for disease progression. Two mutants identified by the above screening process – SSA_1099, encoding an RTX-like protein, and mur2, encoding a peptidoglycan hydrolase – were subsequently evaluated in vivo. Wild type (WT) S. sanguinis reliably induced cardiac vegetations, while the SSA_1099 and mur2 mutants produced either no vegetation or vegetations of small size. Splenomegaly was reduced in both mutant strains compared to WT, while pathology of other distal organs was indistinguishable. Histopathology analyses suggest the cardiac lesions and vegetations in this model resemble those observed in humans. These data indicate that SSA_1099 and mur2 encode virulence factors in S. sanguinis which are integral to pathogenesis of IE.
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Affiliation(s)
- Anthony M Martini
- Department of Microbiology & Immunology, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, United States
| | - Bridget S Moricz
- Department of Microbiology & Immunology, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, United States
| | - Allison K Ripperger
- Department of Microbiology & Immunology, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, United States
| | - Phuong M Tran
- Department of Microbiology & Immunology, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, United States
| | - Molly E Sharp
- Department of Microbiology & Immunology, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, United States
| | - Ana N Forsythe
- Department of Microbiology & Immunology, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, United States
| | - Katarina Kulhankova
- Department of Microbiology & Immunology, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, United States
| | - Wilmara Salgado-Pabón
- Department of Microbiology & Immunology, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, United States
| | - Bradley D Jones
- Department of Microbiology & Immunology, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, United States.,Graduate Program in Genetics, The University of Iowa, Iowa City, IA, United States
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14
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Whelan F, Lafita A, Griffiths SC, Cooper REM, Whittingham JL, Turkenburg JP, Manfield IW, St. John AN, Paci E, Bateman A, Potts JR. Defining the remarkable structural malleability of a bacterial surface protein Rib domain implicated in infection. Proc Natl Acad Sci U S A 2019; 116:26540-26548. [PMID: 31818940 PMCID: PMC6936399 DOI: 10.1073/pnas.1911776116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Streptococcus groups A and B cause serious infections, including early onset sepsis and meningitis in newborns. Rib domain-containing surface proteins are found associated with invasive strains and elicit protective immunity in animal models. Yet, despite their apparent importance in infection, the structure of the Rib domain was previously unknown. Structures of single Rib domains of differing length reveal a rare case of domain atrophy through deletion of 2 core antiparallel strands, resulting in the loss of an entire sheet of the β-sandwich from an immunoglobulin-like fold. Previously, observed variation in the number of Rib domains within these bacterial cell wall-attached proteins has been suggested as a mechanism of immune evasion. Here, the structure of tandem domains, combined with molecular dynamics simulations and small angle X-ray scattering, suggests that variability in Rib domain number would result in differential projection of an N-terminal host-colonization domain from the bacterial surface. The identification of 2 further structures where the typical B-D-E immunoglobulin β-sheet is replaced with an α-helix further confirms the extensive structural malleability of the Rib domain.
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Affiliation(s)
- Fiona Whelan
- Department of Biology, The University of York, YO10 5DD York, United Kingdom
| | - Aleix Lafita
- European Molecular Biology Laboratory, European Bioinformatics Institute, CB10 1SD Hinxton, United Kingdom
| | - Samuel C. Griffiths
- Department of Biology, The University of York, YO10 5DD York, United Kingdom
| | | | - Jean L. Whittingham
- York Structural Biology Laboratory, Department of Chemistry, The University of York, YO10 5DD York, United Kingdom
| | - Johan P. Turkenburg
- York Structural Biology Laboratory, Department of Chemistry, The University of York, YO10 5DD York, United Kingdom
| | - Iain W. Manfield
- Astbury Centre for Structural Molecular Biology, The University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Alexander N. St. John
- Astbury Centre for Structural Molecular Biology, The University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Emanuele Paci
- Astbury Centre for Structural Molecular Biology, The University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Alex Bateman
- European Molecular Biology Laboratory, European Bioinformatics Institute, CB10 1SD Hinxton, United Kingdom
| | - Jennifer R. Potts
- Department of Biology, The University of York, YO10 5DD York, United Kingdom
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15
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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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16
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Pain M, Hjerde E, Klingenberg C, Cavanagh JP. Comparative Genomic Analysis of Staphylococcus haemolyticus Reveals Key to Hospital Adaptation and Pathogenicity. Front Microbiol 2019; 10:2096. [PMID: 31552006 PMCID: PMC6747052 DOI: 10.3389/fmicb.2019.02096] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 08/26/2019] [Indexed: 12/17/2022] Open
Abstract
Staphylococcus haemolyticus is a skin commensal gaining increased attention as an emerging pathogen of nosocomial infections. However, knowledge about the transition from a commensal to an invasive lifestyle remains sparse and there is a paucity of studies comparing pathogenicity traits between commensal and clinical isolates. In this study, we used a pan-genomic approach to identify factors important for infection and hospital adaptation by exploring the genomic variability of 123 clinical isolates and 46 commensal S. haemolyticus isolates. Phylogenetic reconstruction grouped the 169 isolates into six clades with a distinct distribution of clinical and commensal isolates in the different clades. Phenotypically, multi-drug antibiotic resistance was detected in 108/123 (88%) of the clinical isolates and 5/46 (11%) of the commensal isolates (p < 0.05). In the clinical isolates, we commonly identified a homolog of the serine-rich repeat glycoproteins sraP. Additionally, three novel capsular polysaccharide operons were detected, with a potential role in S. haemolyticus virulence. Clinical S. haemolyticus isolates showed specific signatures associated with successful hospital adaption. Biofilm forming S. haemolyticus isolates that are resistant to oxacillin (mecA) and aminoglycosides (aacA-aphD) are most likely invasive isolates whereas absence of these traits strongly indicates a commensal isolate. We conclude that our data show a clear segregation of isolates of commensal origin, and specific genetic signatures distinguishing the clinical isolates from the commensal isolates. The widespread use of antimicrobial agents has probably promoted the development of successful hospital adapted clones of S. haemolyticus clones through acquisition of mobile genetic elements or beneficial point mutations and rearrangements in surface associated genes.
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Affiliation(s)
- Maria Pain
- Pediatric Infections Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway
| | - Erik Hjerde
- Department of Chemistry, Norstruct, UiT The Arcic University of Norway, Tromsø, Norway
| | - Claus Klingenberg
- Pediatric Infections Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway.,Department of Paediatrics, University Hospital of North Norway, Tromsø, Norway
| | - Jorunn Pauline Cavanagh
- Pediatric Infections Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway.,Department of Paediatrics, University Hospital of North Norway, Tromsø, Norway
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17
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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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18
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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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19
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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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20
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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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SssP1, a Streptococcus suis Fimbria-Like Protein Transported by the SecY2/A2 System, Contributes to Bacterial Virulence. Appl Environ Microbiol 2018; 84:AEM.01385-18. [PMID: 30030221 DOI: 10.1128/aem.01385-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 07/10/2018] [Indexed: 12/20/2022] Open
Abstract
Streptococcus suis is an important Gram-positive pathogen in the swine industry and is an emerging zoonotic pathogen for humans. In our previous work, we found a virulent S. suis strain, CZ130302, belonging to a novel serotype, Chz, to be associated with acute meningitis in piglets. However, its underlying mechanisms of pathogenesis remain poorly understood. In this study, we sequenced and analyzed the complete genomes of three Chz serotype strains, including strain CZ130302 and two avirulent strains, HN136 and AH681. By genome comparison, we found two putative genomic islands (GIs) uniquely encoded in strain CZ130302 and designated them 50K GI and 58K GI. In mouse infection model, the deletion of 50K and 58K GIs caused 270-fold and 3-fold attenuation of virulence, respectively. Notably, we identified a complete SecY2/A2 system, coupled with its secretory protein SssP1 encoded in the 50K GI, which contributed to the pathogenicity of strain CZ130302. Immunogold electron microscopy and immunofluorescence analyses indicated that SssP1 could form fimbria-like structures that extend outward from the bacterial cell surface. The sssP1 mutation also attenuated bacterial adherence in human laryngeal epithelial (HEp-2) cells and human brain microvessel endothelial cells (HBMECs) compared with the wild type. Furthermore, we showed that two analogous Ig-like subdomains of SssP1 have sialic acid binding capacities. In conclusion, our results revealed that the 50K GI and the inside SecY2/A2 system gene cluster are related to the virulence of strain CZ130302, and we clarified a new S. suis pathogenesis mechanism mediated by the secretion protein SssP1.IMPORTANCE Streptococcus suis is an important zoonotic pathogen. Here, we managed to identify key factors to clarify the virulence of S. suis strain CZ130302 from a novel serotype, Chz. Notably, it was shown that a fimbria-like structure was significantly connected to the pathogenicity of the CZ130302 strain by comparative genomics analysis and animal infection assays. The mechanisms of how the CZ130302 strain constructs these fimbria-like structures in the cell surface by genes encoding and production transport were subsequently elucidated. Biosynthesis of the fimbria-like structure was achieved by the production of SssP1 glycoproteins, and its construction was dependent on the SecA2/Y2 secretion system. This study identified a visible fimbria-like protein, SssP1, participating in adhesion to host cells and contributing to the virulence in S. suis These findings will promote a better understanding of the pathogenesis of S. suis.
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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: 23] [Impact Index Per Article: 3.8] [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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23
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Role of Neuraminidase-Producing Bacteria in Exposing Cryptic Carbohydrate Receptors for Streptococcus gordonii Adherence. Infect Immun 2018; 86:IAI.00068-18. [PMID: 29661931 DOI: 10.1128/iai.00068-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/13/2018] [Indexed: 12/11/2022] Open
Abstract
Streptococcus gordonii is an early colonizer of the oral cavity. Although a variety of S. gordonii adherence mechanisms have been described, current dogma is that the major receptor for S. gordonii is sialic acid. However, as many bacterial species in the oral cavity produce neuraminidase that can cleave terminal sialic acid, it is unclear whether S. gordonii relies on sialic acid for adherence to oral surfaces or if this species has developed alternative binding strategies. Previous studies have examined adherence to immobilized glycoconjugates and identified binding to additional glycans, but no prior studies have defined the contribution of these different glycan structures in adherence to oral epithelial cells. We determined that the majority of S. gordonii strains tested did not rely on sialic acid for efficient adherence. In fact, adherence of some strains was significantly increased following neuraminidase treatment. Further investigation of representative strains that do not rely on sialic acid for adherence revealed binding not only to sialic acid via the serine-rich repeat protein GspB but also to β-1,4-linked galactose. Adherence to this carbohydrate occurs via an unknown adhesin distinct from those utilized by Streptococcus oralis and Streptococcus pneumoniae Demonstrating the potential biological relevance of binding to this cryptic receptor, we established that S. oralis increases S. gordonii adherence in a neuraminidase-dependent manner. These data suggest that S. gordonii has evolved to simultaneously utilize both terminal and cryptic receptors in response to the production of neuraminidase by other species in the oral environment.
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24
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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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25
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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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26
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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: 26] [Impact Index Per Article: 4.3] [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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Moonens K, Remaut H. Evolution and structural dynamics of bacterial glycan binding adhesins. Curr Opin Struct Biol 2017; 44:48-58. [DOI: 10.1016/j.sbi.2016.12.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/30/2016] [Accepted: 12/05/2016] [Indexed: 01/25/2023]
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Streptococcus oralis Neuraminidase Modulates Adherence to Multiple Carbohydrates on Platelets. Infect Immun 2017; 85:IAI.00774-16. [PMID: 27993975 DOI: 10.1128/iai.00774-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 12/15/2016] [Indexed: 11/20/2022] Open
Abstract
Adherence to host surfaces is often mediated by bacterial binding to surface carbohydrates. Although it is widely appreciated that some bacterial species express glycosidases, previous studies have not considered whether bacteria bind to multiple carbohydrates within host glycans as they are modified by bacterial glycosidases. Streptococcus oralis is a leading cause of subacute infective endocarditis. Binding to platelets is a critical step in disease; however, the mechanisms utilized by S. oralis remain largely undefined. Studies revealed that S. oralis, like Streptococcus gordonii and Streptococcus sanguinis, binds platelets via terminal sialic acid. However, unlike those organisms, S. oralis produces a neuraminidase, NanA, which cleaves terminal sialic acid. Further studies revealed that following NanA-dependent removal of terminal sialic acid, S. oralis bound exposed β-1,4-linked galactose. Adherence to both these carbohydrates required Fap1, the S. oralis member of the serine-rich repeat protein (SRRP) family of adhesins. Mutation of a conserved residue required for sialic acid binding by other SRRPs significantly reduced platelet binding, supporting the hypothesis that Fap1 binds this carbohydrate. The mechanism by which Fap1 contributes to β-1,4-linked galactose binding remains to be defined; however, binding may occur via additional domains of unknown function within the nonrepeat region, one of which shares some similarity with a carbohydrate binding module. This study is the first demonstration that an SRRP is required to bind β-1,4-linked galactose and the first time that one of these adhesins has been shown to be required for binding of multiple glycan receptors.
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Martín-Galiano AJ. The MiiA motif is a common marker present in polytopic surface proteins of oral and urinary tract invasive bacteria. INFECTION GENETICS AND EVOLUTION 2017; 49:283-292. [PMID: 28167145 DOI: 10.1016/j.meegid.2017.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 12/24/2016] [Accepted: 02/02/2017] [Indexed: 12/25/2022]
Abstract
Many surface virulence factors of bacterial pathogens show mosaicism and confounding phylogenetic origin. The Streptococcus gordonii platelet-binding GspB protein, the Streptococcus sanguinis SrpA adhesin and the Streptococcus pneumoniae DiiA protein, share an imperfect 27-residue motif. Given the disparate domain architectures of these proteins and its association to invasive disease, this motif was named MiiA from Multiarchitecture invasion-involved motif A. MiiA is predicted to adopt a beta-sheet folding, probably related to the Ig-like fold, with a symmetrical positioning of two conserved aspartic residues. A specific hidden Markov model profiling MiiA was built, which specifically detected the motif in proteins from 58 species, mainly in cell-wall proteins from Gram-positive bacteria. These proteins contained one to ten MiiA motifs, which were embedded within larger repeat units of 70-82 residues. MiiA motifs combined to other domains and elements such as coiled-coils and low-complexity regions. The species carrying MiiA-proteins included commensals from the urogenital tract and the oral cavity, which can cause opportunistic endocarditis and sepsis. Intra-protein MiiA repeats showed a complex mixture of orthologal, paralogal and inter-species relationships, suggestive of a multistep origin. Presence of these repeats in proteins involved in oligosaccharide recognition and lifestyle of species suggest a putative function for MiiA repeats in sugars binding, probably those present in receptors of epithelial and blood cells. MiiA modules appear to have been transferred horizontally between species co-habiting in the same niche to create their own MiiA-containing determinants. The present work provides a global study and a catalog of potential MiiA virulence factors that should be analyzed experimentally.
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Affiliation(s)
- Antonio J Martín-Galiano
- Instituto de Salud Carlos III, Centro Nacional de Microbiología, Carretera a Pozuelo, km 2.2, Majadahonda, 28220 Madrid, Spain.
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Loukachevitch LV, Bensing BA, Yu H, Zeng J, Chen X, Sullam PM, Iverson TM. Structures of the Streptococcus sanguinis SrpA Binding Region with Human Sialoglycans Suggest Features of the Physiological Ligand. Biochemistry 2016; 55:5927-5937. [PMID: 27685666 PMCID: PMC5388602 DOI: 10.1021/acs.biochem.6b00704] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Streptococcus sanguinis is a leading cause of bacterial infective endocarditis, a life-threatening infection of heart valves. S. sanguinis binds to human platelets with high avidity, and this adherence is likely to enhance virulence. Previous studies suggest that a serine-rich repeat adhesin termed SrpA mediates the binding of S. sanguinis to human platelets via its interaction with sialoglycans on the receptor GPIbα. However, in vitro binding assays with SrpA and defined sialoglycans failed to identify specific high-affinity ligands. To improve our understanding of the interaction between SrpA and human platelets, we determined cocrystal structures of the SrpA sialoglycan binding region (SrpABR) with five low-affinity ligands: three sialylated trisaccharides (sialyl-T antigen, 3'-sialyllactose, and 3'-sialyl-N-acetyllactosamine), a sialylated tetrasaccharide (sialyl-LewisX), and a sialyl galactose disaccharide component common to these sialoglyans. We then combined structural analysis with mutagenesis to further determine whether our observed interactions between SrpABR and glycans are important for binding to platelets and to better map the binding site for the physiological receptor. We found that the sialoglycan binding site of SrpABR is significantly larger than the sialoglycans cocrystallized in this study, which suggests that binding of SrpA to platelets either is multivalent or occurs via a larger, disialylated glycan.
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Affiliation(s)
| | - Barbara A. Bensing
- Division of Infectious Diseases, Veterans Affairs Medical Center, University of California at San Francisco and the Northern California Institute for Research and Education, San Francisco, California 94121, USA
| | - Hai Yu
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Jie Zeng
- Department of Chemistry, University of California, Davis, CA 95616, USA,School of Food Science, Henan Institute of Science and Technology, Xinxiang, 453003, China
| | - Xi Chen
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Paul M. Sullam
- Division of Infectious Diseases, Veterans Affairs Medical Center, University of California at San Francisco and the Northern California Institute for Research and Education, San Francisco, California 94121, USA
| | - T M Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA,Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, USA,Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, USA,Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, USA,Corresponding Author To whom correspondence should be addressed:
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Bensing BA, Khedri Z, Deng L, Yu H, Prakobphol A, Fisher SJ, Chen X, Iverson TM, Varki A, Sullam PM. Novel aspects of sialoglycan recognition by the Siglec-like domains of streptococcal SRR glycoproteins. Glycobiology 2016; 26:1222-1234. [PMID: 27037304 DOI: 10.1093/glycob/cww042] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/23/2016] [Accepted: 03/25/2016] [Indexed: 12/15/2022] Open
Abstract
Serine-rich repeat glycoproteins are adhesins expressed by commensal and pathogenic Gram-positive bacteria. A subset of these adhesins, expressed by oral streptococci, binds sialylated glycans decorating human salivary mucin MG2/MUC7, and platelet glycoprotein GPIb. Specific sialoglycan targets were previously identified for the ligand-binding regions (BRs) of GspB and Hsa, two serine-rich repeat glycoproteins expressed by Streptococcus gordonii While GspB selectively binds sialyl-T antigen, Hsa displays broader specificity. Here we examine the binding properties of four additional BRs from Streptococcus sanguinis or Streptococcus mitis and characterize the molecular determinants of ligand selectivity and affinity. Each BR has two domains that are essential for sialoglycan binding by GspB. One domain is structurally similar to the glycan-binding module of mammalian Siglecs (sialic acid-binding immunoglobulin-like lectins), including an arginine residue that is critical for glycan recognition, and that resides within a novel, conserved YTRY motif. Despite low sequence similarity to GspB, one of the BRs selectively binds sialyl-T antigen. Although the other three BRs are highly similar to Hsa, each displayed a unique ligand repertoire, including differential recognition of sialyl Lewis antigens and sulfated glycans. These differences in glycan selectivity were closely associated with differential binding to salivary and platelet glycoproteins. Specificity of sialoglycan adherence is likely an evolving trait that may influence the propensity of streptococci expressing Siglec-like adhesins to cause infective endocarditis.
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Affiliation(s)
- Barbara A Bensing
- Department of Medicine, The San Francisco Veterans Affairs Medical Center, and the University of California, San Francisco, San Francisco, CA 94121, USA
| | - Zahra Khedri
- The Glycobiology Research and Training Center, and the Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, CA 92093, USA
| | - Lingquan Deng
- The Glycobiology Research and Training Center, and the Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, CA 92093, USA
| | - Hai Yu
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Akraporn Prakobphol
- Department of Obstetrics, Gynecology and Reproductive Sciences, The University of California, San Francisco, San Francisco, CA 94143, USA
| | - Susan J Fisher
- Department of Obstetrics, Gynecology and Reproductive Sciences, The University of California, San Francisco, San Francisco, CA 94143, USA
| | - Xi Chen
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Tina M Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, TN 27232, USA
| | - Ajit Varki
- The Glycobiology Research and Training Center, and the Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, CA 92093, USA
| | - Paul M Sullam
- Department of Medicine, The San Francisco Veterans Affairs Medical Center, and the University of California, San Francisco, San Francisco, CA 94121, USA
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