Localization of the equine IgG-binding domain in the fibrinogen-binding protein (FgBP) of Streptococcus equi subsp. equi.
Abstract: Fibrinogen-binding protein (FgBP, also termed SeM) is a cell-wall-associated anti-phagocytic M-like protein of the equine pathogen Streptococcus equi subsp. equi, and binds fibrinogen (Fg) and IgG. FgBP binds Fg avidly through residues located at the extreme N terminus of the molecule, whereas the IgG-binding site is more centrally located between the A and B repeats. FgBP binds equine IgG4 and IgG7 subclasses through interaction with the CH2-CH3 interdomain region of IgG-Fc, and possesses overlapping Fc-binding sites with protein A and protein G. In this study, FgBP truncates containing defined internal deletions were used to identify a stretch of 14 aa (residues 335-348) critical for IgG binding. Protein chimeras consisting of the non-IgG-binding alpha-helical coiled-coil M5 protein fused to FgBP sequences were used to identify a minimal equine IgG-binding domain consisting of residues 329-360. Competition ELISA tests suggested that IgG does not compromise Fg binding and vice versa.
Publication Date: 2009-05-07 PubMed ID: 19423628DOI: 10.1099/mic.0.028845-0Google Scholar: Lookup
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- Journal Article
Summary
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This study aims to identify the specific region of the fibrinogen-binding protein (FgBP) that binds to horse immunoglobulin G (IgG) in Streptococcus equi, a bacteria causing horse infections. The research demonstrates that a small section of 14 amino acids is critical for this interaction and determines that this binding does not interfere with fibrinogen binding.
Introduction and Background
- The focus of the research is FgBP, a protein associated with the equine pathogen Streptococcus equi subsp. equi, which is responsible for horse infections.
- These specific proteins bind to fibrinogen (Fg) and equine immunoglobulin (IgG), both important proteins involved in clotting and immune response respectively.
- The location of the fibrinogen binding site on FgBP had previously been identified. However, the IgG binding site was not yet mapped out, which led to this study.
Identifying the IgG-binding Site
- Researchers used “truncated” (shortened) versions of the FgBP protein, essentially creating versions of it with specific portions removed.
- This allowed them to narrow down and pinpoint a stretch of 14 amino acids (the building blocks of proteins), specifically residues 335-348, that were crucial for the protein’s ability to bind with IgG.
- In addition, the study also identified a minimal equine IgG-binding domain of residues 329-360 using protein chimeras. These are molecules created by joining two different proteins, in this case, FgBP and M5 protein, which does not bind IgG.
Competition ELISA Tests
- The researchers also conducted competition ELISA tests. This is a technique used to measure the concentration of antibodies (like IgG) in a sample.
- These tests helped the team determine that the binding of IgG to FgBP does not interfere with the binding of fibrinogen (Fg) to FgBP, and the other way around.
- This is crucial as it means that the protein can bind both types of molecules simultaneously, potentially playing a role in both clot formation and immune responses.
Cite This Article
APA
Meehan M, Lewis MJ, Byrne C, O'Hare D, Woof JM, Owen P.
(2009).
Localization of the equine IgG-binding domain in the fibrinogen-binding protein (FgBP) of Streptococcus equi subsp. equi.
Microbiology (Reading), 155(Pt 8), 2583-2592.
https://doi.org/10.1099/mic.0.028845-0 Publication
Researcher Affiliations
- Department of Microbiology, Moyne Institute of Preventative Medicine, Trinity College, Dublin 2, Ireland.
- Division of Medical Sciences, University of Dundee Medical School, Ninewells Hospital, Dundee DD1 9SY, UK.
- Department of Microbiology, Moyne Institute of Preventative Medicine, Trinity College, Dublin 2, Ireland.
- Department of Microbiology, Moyne Institute of Preventative Medicine, Trinity College, Dublin 2, Ireland.
- Division of Medical Sciences, University of Dundee Medical School, Ninewells Hospital, Dundee DD1 9SY, UK.
- Department of Microbiology, Moyne Institute of Preventative Medicine, Trinity College, Dublin 2, Ireland.
MeSH Terms
- Amino Acid Sequence
- Animals
- Bacterial Proteins / chemistry
- Bacterial Proteins / genetics
- Bacterial Proteins / metabolism
- Binding Sites
- Carrier Proteins / chemistry
- Carrier Proteins / genetics
- Carrier Proteins / metabolism
- DNA, Bacterial / genetics
- Fibrinogen / metabolism
- Horses
- Immunoglobulin G / metabolism
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Protein Binding
- Protein Structure, Tertiary
- Recombinant Proteins / chemistry
- Recombinant Proteins / genetics
- Recombinant Proteins / metabolism
- Streptococcus equi / genetics
- Streptococcus equi / metabolism
Citations
This article has been cited 7 times.- Boyle AG, Rankin SC, O'Shea K, Stefanovski D, Peng J, Song J, Bau HH. Detection of Streptococcus equi subsp. equi in guttural pouch lavage samples using a loop-mediated isothermal nucleic acid amplification microfluidic device. J Vet Intern Med 2021 May;35(3):1597-1603.
- Mitchell C, Steward KF, Charbonneau ARL, Walsh S, Wilson H, Timoney JF, Wernery U, Joseph M, Craig D, van Maanen K, Hoogkamer-van Gennep A, Leon A, Witkowski L, Rzewuska M, Stefańska I, Żychska M, van Loon G, Cursons R, Patty O, Acke E, Gilkerson JR, El-Hage C, Allen J, Bannai H, Kinoshita Y, Niwa H, Becú T, Pringle J, Guss B, Böse R, Abbott Y, Katz L, Leggett B, Buckley TC, Blum SE, Cruz López F, Fernández Ros A, Marotti Campi MC, Preziuso S, Robinson C, Newton JR, Schofield E, Brooke B, Boursnell M, de Brauwere N, Kirton R, Barton CK, Abudahab K, Taylor B, Yeats CA, Goater R, Aanensen DM, Harris SR, Parkhill J, Holden MTG, Waller AS. Globetrotting strangles: the unbridled national and international transmission of Streptococcus equi between horses. Microb Genom 2021 Mar;7(3).
- D'Gama JD, Ma Z, Zhang H, Liu X, Fan H, Morris ERA, Cohen ND, Cywes-Bentley C, Pier GB, Waldor MK. A Conserved Streptococcal Virulence Regulator Controls the Expression of a Distinct Class of M-Like Proteins. mBio 2019 Oct 22;10(5).
- Bao YJ, Li Y, Liang Z, Agrahari G, Lee SW, Ploplis VA, Castellino FJ. Comparative pathogenomic characterization of a non-invasive serotype M71 strain Streptococcus pyogenes NS53 reveals incongruent phenotypic implications from distinct genotypic markers. Pathog Dis 2017 Jul 31;75(5).
- Bergmann S, Eichhorn I, Kohler TP, Hammerschmidt S, Goldmann O, Rohde M, Fulde M. SCM, the M Protein of Streptococcus canis Binds Immunoglobulin G. Front Cell Infect Microbiol 2017;7:80.
- Velineni S, Timoney JF. Characterization and protective immunogenicity of the SzM protein of Streptococcus zooepidemicus NC78 from a clonal outbreak of equine respiratory disease. Clin Vaccine Immunol 2013 Aug;20(8):1181-8.
- Wan J, Weldon E, Ganser G, Morris ERA, Hughes EV, Bordin AI, Heine PA, Hust M, Cohen ND, Gill JJ, Liu M. Immunogenic Streptococcus equi cell surface proteins identified by ORFeome phage display. mSphere 2025 Dec 23;10(12):e0062625.
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