Identification of an immunodominant region on a group A Streptococcus T-antigen reveals temperature-dependent motion in pili
Group A Streptococcus (GAS) is a globally important pathogen causing a broad range of human diseases. GAS pili are elongated proteins with a backbone comprised repeating T-antigen subunits, which extend from the cell surface and have important roles in adhesion and establishing infection. No GAS vac...
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| Format: | Article |
| Language: | English |
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Taylor & Francis Group
2023-12-01
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| Series: | Virulence |
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| Online Access: | https://www.tandfonline.com/doi/10.1080/21505594.2023.2180228 |
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| author | Jeremy M. Raynes Paul G. Young Natalie Lorenz Jacelyn M.S. Loh Reuben McGregor Edward N. Baker Thomas Proft Nicole J. Moreland |
| author_facet | Jeremy M. Raynes Paul G. Young Natalie Lorenz Jacelyn M.S. Loh Reuben McGregor Edward N. Baker Thomas Proft Nicole J. Moreland |
| author_sort | Jeremy M. Raynes |
| collection | DOAJ |
| description | Group A Streptococcus (GAS) is a globally important pathogen causing a broad range of human diseases. GAS pili are elongated proteins with a backbone comprised repeating T-antigen subunits, which extend from the cell surface and have important roles in adhesion and establishing infection. No GAS vaccines are currently available, but T-antigen-based candidates are in pre-clinical development. This study investigated antibody-T-antigen interactions to gain molecular insight into functional antibody responses to GAS pili. Large, chimeric mouse/human Fab-phage libraries generated from mice vaccinated with the complete T18.1 pilus were screened against recombinant T18.1, a representative two-domain T-antigen. Of the two Fab identified for further characterization, one (designated E3) was cross-reactive and also recognized T3.2 and T13, while the other (H3) was type-specific reacting with only T18.1/T18.2 within a T-antigen panel representative of the major GAS T-types. The epitopes for the two Fab, determined by x-ray crystallography and peptide tiling, overlapped and mapped to the N-terminal region of the T18.1 N-domain. This region is predicted to be buried in the polymerized pilus by the C-domain of the next T-antigen subunit. However, flow cytometry and opsonophagocytic assays showed that these epitopes were accessible in the polymerized pilus at 37°C, though not at lower temperature. This suggests that there is motion within the pilus at physiological temperature, with structural analysis of a covalently linked T18.1 dimer indicating “knee-joint” like bending occurs between T-antigen subunits to expose this immunodominant region. This temperature dependent, mechanistic flexing provides new insight into how antibodies interact with T-antigens during infection. |
| format | Article |
| id | doaj-art-30a4e018f51b48a6a8ed8bcce2a52dfb |
| institution | Matheson Library |
| issn | 2150-5594 2150-5608 |
| language | English |
| publishDate | 2023-12-01 |
| publisher | Taylor & Francis Group |
| record_format | Article |
| series | Virulence |
| spelling | doaj-art-30a4e018f51b48a6a8ed8bcce2a52dfb2025-06-30T04:55:51ZengTaylor & Francis GroupVirulence2150-55942150-56082023-12-0114110.1080/21505594.2023.2180228Identification of an immunodominant region on a group A Streptococcus T-antigen reveals temperature-dependent motion in piliJeremy M. Raynes0Paul G. Young1Natalie Lorenz2Jacelyn M.S. Loh3Reuben McGregor4Edward N. Baker5Thomas Proft6Nicole J. Moreland7School of Medical Sciences, The University of Auckland, Auckland, New ZealandMaurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New ZealandSchool of Medical Sciences, The University of Auckland, Auckland, New ZealandSchool of Medical Sciences, The University of Auckland, Auckland, New ZealandSchool of Medical Sciences, The University of Auckland, Auckland, New ZealandMaurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New ZealandSchool of Medical Sciences, The University of Auckland, Auckland, New ZealandSchool of Medical Sciences, The University of Auckland, Auckland, New ZealandGroup A Streptococcus (GAS) is a globally important pathogen causing a broad range of human diseases. GAS pili are elongated proteins with a backbone comprised repeating T-antigen subunits, which extend from the cell surface and have important roles in adhesion and establishing infection. No GAS vaccines are currently available, but T-antigen-based candidates are in pre-clinical development. This study investigated antibody-T-antigen interactions to gain molecular insight into functional antibody responses to GAS pili. Large, chimeric mouse/human Fab-phage libraries generated from mice vaccinated with the complete T18.1 pilus were screened against recombinant T18.1, a representative two-domain T-antigen. Of the two Fab identified for further characterization, one (designated E3) was cross-reactive and also recognized T3.2 and T13, while the other (H3) was type-specific reacting with only T18.1/T18.2 within a T-antigen panel representative of the major GAS T-types. The epitopes for the two Fab, determined by x-ray crystallography and peptide tiling, overlapped and mapped to the N-terminal region of the T18.1 N-domain. This region is predicted to be buried in the polymerized pilus by the C-domain of the next T-antigen subunit. However, flow cytometry and opsonophagocytic assays showed that these epitopes were accessible in the polymerized pilus at 37°C, though not at lower temperature. This suggests that there is motion within the pilus at physiological temperature, with structural analysis of a covalently linked T18.1 dimer indicating “knee-joint” like bending occurs between T-antigen subunits to expose this immunodominant region. This temperature dependent, mechanistic flexing provides new insight into how antibodies interact with T-antigens during infection.https://www.tandfonline.com/doi/10.1080/21505594.2023.2180228Streptococcus pyogenesT-antigenpilusantibodytemperaturemotion |
| spellingShingle | Jeremy M. Raynes Paul G. Young Natalie Lorenz Jacelyn M.S. Loh Reuben McGregor Edward N. Baker Thomas Proft Nicole J. Moreland Identification of an immunodominant region on a group A Streptococcus T-antigen reveals temperature-dependent motion in pili Virulence Streptococcus pyogenes T-antigen pilus antibody temperature motion |
| title | Identification of an immunodominant region on a group A Streptococcus T-antigen reveals temperature-dependent motion in pili |
| title_full | Identification of an immunodominant region on a group A Streptococcus T-antigen reveals temperature-dependent motion in pili |
| title_fullStr | Identification of an immunodominant region on a group A Streptococcus T-antigen reveals temperature-dependent motion in pili |
| title_full_unstemmed | Identification of an immunodominant region on a group A Streptococcus T-antigen reveals temperature-dependent motion in pili |
| title_short | Identification of an immunodominant region on a group A Streptococcus T-antigen reveals temperature-dependent motion in pili |
| title_sort | identification of an immunodominant region on a group a streptococcus t antigen reveals temperature dependent motion in pili |
| topic | Streptococcus pyogenes T-antigen pilus antibody temperature motion |
| url | https://www.tandfonline.com/doi/10.1080/21505594.2023.2180228 |
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